Symposium Organizers
Philippe Bergonzo, CEA Saclay
Timothy Grotjohn, Michigan State University
Mutsuko Hatano, Tokyo Institute of Technology
Christoph Nebel, Fraunhofer IAF
Symposium Support
Applied Diamond, Inc.
Arios Ltd.
CARAT Systems
CIVIDEC Instrumentation GmbH
Cline Innovations, LLC
DiamFab
ICDAT LTD.
Microwave Enterprises, Ltd.
Fraunhofer Center for Coatings and Diamond Technologies- Michigan State University
New Diamond Technology, LLC
Seki Diamond Systems
EM06.01: Towards Large Area Diamond
Session Chairs
Monday PM, November 27, 2017
Hynes, Level 1, Room 108
8:30 AM - EM06.01
Introductory Remarks by Philippe Bergonzo
Show Abstract8:45 AM - *EM06.01.01
Heteroepitaxial Diamond for Electronic and Detector Applications—Recent Progress in Material Synthesis and Characterization of Electronic Properties
Matthias Schreck 1 , Michael Mayr 1 , Michael Traeger 2 , Mladen Kiš 2 , Patrik Scajev 3 , André Sartori 4 , Stefan Gsell 1 , Martin Fischer 1
1 Institute of Physics, University of Augsburg, Augsburg Germany, 2 , GSI Helmholtzzentrum für Schwerionenforschung , D-64291 Darmstadt Germany, 3 Institute of Applied Research, Vilnius University, LT-10257 Vilnius Lithuania, 4 3mE, Delft University of Technology, 2628 CD Delft Netherlands
Show AbstractDevices for high end applications which make use of diamond’s unique physical properties typically require single crystals in order to guarantee that the extreme material properties are not deteriorated by the presence of grain boundaries. We have recently shown that heteroepitaxial nucleation and growth on Ir/YSZ/Si(001) can provide wafer-size single-crystal diamond with a diameter greater than 3 inch and a total weight of 155 carat [1].
Due to the characteristic features of the nucleation process on iridium surfaces, the diamond layers start with a high density of dislocations. Systematic reduction of their density is feasible by growth of thick layers using suitable growth conditions. However, this strategy will also meet its limit which we currently estimate at 106 - 107cm-2. It is therefore important to explore the limiting role of dislocations for the performance of electronic devices, i.e. their influence on charge carrier lifetime, trapping, mobility, breakdown field strength etc.
In the first part of this presentation the state of the art of diamond growth by heteroepitaxy on Ir/YSZ/Si will be reviewed briefly. In the second part recent experiments on the electronic properties will be described. These comprise Schottky barrier diodes manufactured from heteroepitaxial diamond, the charge collection efficiency measured under α-particle irradiation and charge carrier lifetime measurements. The results will be compared with the data from single crystal diamond synthesized by other methods.
[1] M. Schreck, S. Gsell, R. Brescia, M. Fischer, Sci. Rep. 7, 44462 (2017).
9:15 AM - EM06.01.02
Fundamentals of Bias Enhance Nucleation/Bias Enhanced Growth of Ultrananocrystalline Diamond Films on Tungsten/Silicon Substrates by Hot Filament Chemical Vapor Deposition for Large Areas Application
Jesus Alcantar-Peña 3 1 , Elida De Obaldia 2 , Jorge Montes 4 1 , Karam Kang 1 6 , Maria J Arellano-Jimenez 5 , Jorge Ortega-Aguilar 5 , Dainet Berman-Mendoza 3 , Miguel Yacaman 5 , Orlando Auciello 1 6
3 Departamento de Investigación en Física, Universidad de Sonora, Hermosillo, Sonora, Mexico, 1 Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas, United States, 2 Facultad de Ciencia y Tecnología, Universidad Tecnológica de Panamá, Panama, Panama, Panama, 4 Departamento de Física, Universidad de Sonora, Hermosillo, Sonora, Mexico, 6 Department of Bioengineering, University of Texas at Dallas, Richardson, Texas, United States, 5 Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas, United States
Show AbstractPolycrystalline diamond films have been and are investigated due to their unique combination of properties such as high wear resistance, highest hardness relative to any other film, lowest friction coefficient compared with metal and ceramic coatings, chemical inertness, excellent thermal conductivity (~1500 W/K m, close to that of single crystal diamond ~2100 W/K m) perpendicular to the film surface and in the film plane for microcrystalline diamond (≥ 1 μm grain size), tunable electronic properties, and biocompatible properties.
This presentation will describe the results from research and development of Bias Enhance Nucleation and Bias enhance Growth (BEN-BEG) to growth polycrystalline diamond on large areas Silicon wafer coated with 40 nm of Tungsten layer. The BEN-BEG process to growth diamond films eliminate the conventional chemical seeding process used today. The studies discussed are focus on understanding the BEN mechanism by varying the BEN time between 0.5 and 2.5 hrs. Following the BEN process, films were grown for 2.0 hrs without bias. Evidence of very homogeneous nucleation by BEN appears for 2.0 and 2.5 hrs. However, at 2.5 hrs of BEN, signs of etching of the diamond film is observed, likely due to long exposure ion bombardment-induced sputtering of the film. According to the studies made until now, BEN for 2.0 hrs appears to be the optimum process to growth very dense film across 100 diameter wafer. HRTEM studies show that 2.0 hrs. BEN induce the growth of tungsten carbide layer with crystals orientation (001 and 101), which induce the formation of diamond grains (111), followed by change of diamond grain orientation to (220) and (311). These results show that the BEN process could be used to tailor orientation of UNCD film grains. In addition, it was demonstrated that the HFCVD BEN-BEG process can be used to grow diamond films selectively on electrically conductive patterns produced on insulating substrate surfaces, providing a pathway for fabrication of diamond based devices on SiO2/Si substrates.
9:30 AM - EM06.01.03
Growing Ultra-Large Type IIa HPHT Single-Crystal Diamonds
Yury Loguinov 1
1 , New Diamond Technology, Saint Petersburg Russian Federation
Show AbstractNEW DIAMOND TECHNOLOGY company was founded in 2014 for growing nitrogen-free single-crystal type IIa diamonds of large sizes and superior quality. For this purpose we purchased and improved the most modern equipment, created and developed unique technology and formed the best team of professionals from all over the world.
Only one year later, the company has set several world-records in the field of growing and treating diamonds. These records are still unbroken and the company is annually aiming for more by improving achievements constantly.
We actively develop Jewelry, Industrial and Scientific international market sectors. We explore innovative approaches and technologies to improve the quality of diamond production. The company is focused on partnership with international research institutes and innovative companies to create mutually-beneficial collaboration with the main purpose – to contribute the whole diamond market.
Our mission is to mass produce the world’s highest quality single-crystal lab-grown diamonds - large, no inclusions and defects, low dislocations and nitrogen levels. To reach our objective we’ve developed proprietary technology, purchased state-of-the-art equipment and assembled a team of world-renowned professionals.
We would like to present our world-record diamonds, the largest SCD plates, diamond anvils and lenses to Material Research Society and all the participants.
9:45 AM - EM06.01.04
Toward the Growth of Large Area MPACVD Single Crystal Diamond
Amanda Charris 1 , Jes Asmussen 1
1 Electrical Engineering , Michigan State University, East Lansing, Michigan, United States
Show AbstractThe growth of high-quality single crystal diamond SCD CVD is imperative for optical and electronic diamond applications. However, as required for industrial applications, is it mandatory to grow large, defect-free SCD, at high growth rates.
We recently reported by modifying the geometry of the substrate holder the growth of larger, PCD rimless SCD [1]. In this set of experiments, the substrate temperature was held constant. The results indicated that by only varying one holder dimension, i.e. it is depth, the final diamond shapes, and final top surfaces areas were changed. Shallow pockets had enhanced lateral growth rates and larger final surface area gains. Deep pockets did not grow larger area SCD crystals, but had a reduced lateral area growth rates and associated reduced area gain. The deeper pockets often resulted in final SCD crystals with smaller final surface areas relative to the surfaces areas of the original seeds. Additionally, we extended the pocket area growth to growth cycles that only varied the substrate temperature versus time. These experiments also showed an enhancement in the lateral growth area over the thickness growth that for some growth cycles. [2].
Here we present the details of additional experiments that have the objective to further enlarge the SCD growth. The experiments used a 2.45 GHz microwave plasma CVD reactor operating at an experimental pressure of 240 Torr, H2 flow rate of 400 sccm, and 5% CH4/H2 methane concentration. Diamond growth rates were in the range of 24 µm/h – 31 µm/h. The SCD seed was placed in a modified geometry pocket substrate holder. By either adjusting (1) the pocket holder width and the pocket holder depth or (2) by adding a second growth step the lateral diamond growth was enhanced.
For example, at a constant substrate temperature versus time, SCD were grown in a fixed pocket depth of 2.6 mm. The variable pocket widths were 6.0 mm, 6.6 mm and 7.0mm. As a result, in a single run of approximately 45 hours, the diamond top surface was expanded up to 2.2 times relative to the original HPHT seed (12.25 mm2) surfaces. The top surface area further increased by adding a second growth step. The characterization of the grown diamond material will be presented.
References
[1] A. Charris, S. Nad, and J. Asmussen, “Exploring constant substrate temperature and constant high pressure SCD growth using variable pocket holder depths,” Diam. Relat. Mater., vol. 76, 2017.
[2] S. Nad, A. Charris, and J. Asmussen, “MPACVD growth of single crystalline diamond substrates with PCD rimless and expanding surfaces,” Appl. Phys. Lett., vol. 109, no. 16, 2016.
EM06.02: What Diamond is Good at...
Session Chairs
Monday PM, November 27, 2017
Hynes, Level 1, Room 108
10:30 AM - *EM06.02.01
Diamond Power Devices: State of the Art, Modelling and Figures of Merit
Nazareno Donato 1 , Nicolas Rouger 2 , Florin Udrea 1
1 , University of Cambridge, Cambridge United Kingdom, 2 , Laplace, Toulouse France
Show AbstractThe presentation will present the state of the art in power devices and discuss the modelling and design challenges for Diamond devices. The presentation will finish with a critical view on the widely accepted figures of merit and their applicability to power devices.
11:00 AM - *EM06.02.02
Lattice Thermal Conductivity and Grain/Grain Thermal Resistance in Polycrystalline Diamond
Martin Kuball 1 , Julian Anaya 1 , Mark Goorsky 2 , Samuel Graham 3 , Karl Hobart 4
1 , University of Bristol, Bristol United Kingdom, 2 , University of California, Los Angeles, Los Angeles, California, United States, 3 , Georgia Institute of Technology, Atlanta, Georgia, United States, 4 , U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractThe high thermal conductivity of polycrystalline diamond has been widely exploited for thermal management of electronic, opto-electronic devices, x-ray and other windows. While for many applications the first microns of diamond growth from nucleation is removed by polishing due to its extensive microstructure, the recent integration of diamond with GaN high electron mobility transistors (HEMTs) has revived the interest in a better understanding of the diamond properties in this near-nucleation region, since a low thermal conductivity in this region is a bottleneck for this technology.
The in-plane and cross-plane thermal conductivity of polycrystalline diamond near its nucleation region have been measured by Raman thermography assisted by TiO2 nanoparticles and by picosecond time-domain thermoreflectance (TDTR). This information has been combined with a finite element thermal model making use of the real grain structure, including information on the grain orientation, of the film extracted by transmission electron microscopy (TEM). This methodology allows to simultaneously determine the thermal resistance between grains and the lattice thermal conductivity of the sample without any adjustable parameter. The results show that the lattice thermal conductivity of the near nucleation diamond is 5-8 times smaller than the one observed in single-crystalline diamond; the thermal resistance between grains is at least one order of magnitude higher than values predicted by molecular dynamic simulations. Finally, we show how the anisotropy in thermal conductivity observed in polycrystalline diamond naturally emerges from its grain structure and the thermal resistance at grain boundaries.
11:30 AM - EM06.02.03
Enhanced Thermal Management of Active and Passive High Power RF Devices Using CVD Diamond
Firooz Faili 2 , Ian Friel 1 , Thomas Obeloer 2 , Daniel Twitchen 1
2 , Element Six Technologies US Corporation, Santa Clara, California, United States, 1 , Element Six Ltd, Global Innovation Centre, Harwell United Kingdom
Show AbstractHigh power RF and microwave frequency applications, such as high performance phased array radars or satellite communications, require advanced materials and solutions for thermal management, if the intrinsic performance capabilities of RF devices and components are to be achieved.
CVD diamond for thermal solutions is a consistent engineering material beyond the norm, capable of handling the substantial power densities involved, and therefore providing a platform for high power, high frequency device design. Where CVD diamond is used as a bonded heat spreader or substrate material we demonstrate the potential for significant performance gains for both active and passive RF power devices.
Inclusion of a CVD diamond heat spreader within a hybrid micro-cooler arrangement, is demonstrated experimentally to reduce device temperature hotspots by up to 40% for 70W of total dissipated power. Conversely, it is shown that the power handling capability of the system, for a hotspot temperature of 160 °C, can be increased from around 70 to 110 W. Finite element simulations are used to predict performance as a function of system geometry and the thermal grade of CVD diamond used.
For high power and high frequency RF resistors, substrate materials must show excellent power handling capabilities whilst also minimising the parasitic capacitance. Due to its high thermal conductivity and low dielectric permittivity, CVD diamond is ideally suited to enable significant improvements in performance over what is achievable with conventional substrate materials, such as AlN and BeO. Simulations of a single-side mounted resistor soldered to a copper heatsink, show that for 100 W dissipated at a peak temperature of 125 °C, the parasitic capacitance of the resistor can be 3 to 5 times less using CVD diamond substrates compared to BeO and AlN. Conversely, the high frequency performance of the latter devices (consistent with a voltage standing wave ratio less than 1.25) is limited to the S-band range (<5 GHz), whilst those using CVD diamond substrates are predicted to operate above 10 GHz.
11:45 AM - EM06.02.04
Transfer and Characterization of Epitaxial Graphene Catalytically-Grown on the Diamond (111) Surface
Ben Reed 1 , Di Hu 1 , Simon Cooil 2 , Andrew Evans 1
1 , Aberystwyth University, Aberystwyth United Kingdom, 2 Physics, NTNU, Trondheim Norway
Show AbstractThe diamond (111) surface provides a close 2-d lattice match to graphene and is hence an ideal template substrate for growth, as well as an ideal dielectric substrate for device fabrication. High-quality epitaxial graphene can be formed on this diamond surface by annealing at high temperature (> 1000°C) in ultrahigh vacuum, but we have shown that it can be grown at temperatures as low as 500°C by depositing transition metal catalysts on the surface prior to heating. The sp2 carbon produced maintains perfect registry with the underlying diamond substrate and, unlike chemical vapor deposition methods on copper, can be grown in single and multiple layers. To characterize and control this process, we have developed in-situ and real-time monitoring methods based on electron and optical emission and scattering. The process has been optimized by varying the diamond surface preparation, the thickness of the catalyst layer, and the temperature profile during heating. From this work, we have determined the minimum thickness of catalyst required to induce low temperature graphitization. Multilayer graphene films fabricated by this method have been transferred to a polydimethylsiloxane (PDMS) polymer support and the quality confirmed by Raman spectroscopy, atomic force microscopy (AFM), and electronic force microscopy (EFM).
EM06.03: Novel Devices
Session Chairs
Monday PM, November 27, 2017
Hynes, Level 1, Room 108
1:45 PM - *EM06.03.01
Novel Boron Doped Diamond Nanowire Structures and Devices
Alex Pakpour-Tabrizi 1 , S. D Sawtelle 2 , Z.A. Kobos 2 , Shari Yosinski 2 , Federico Mazzola 3 , Sanjoy K Mahatha 4 , Alex Schenk 3 , Ann Julie Holt 3 , Philip Hofmann 4 , James Butler 5 , Jill Miwa 4 , Justin Wells 3 , Mark Reed 2 , Richard Jackman 1
1 , University College London, London United Kingdom, 2 Department of Electrical Engineering, Yale, New Haven, Connecticut, United States, 3 Physics, NTNU, Trondheim Norway, 4 Physics, Aarhus University, Aarhus Denmark, 5 Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod Russian Federation
Show AbstractThrough extensive synchrotron-based x-ray experiments, allied to electrical studies, it is shown that boron doped diamond maintains remarkably bulk-like electronic properties even when the doping distribution (10^20 B/cm^3 peak doping level) is reduced to a few nanometres FWHM. From this ‘∂-doped’ single crystal diamond, lateral Ohmic nanowires (l-dNWs) are patterned and electrically addressed using Electron Beam Lithography (EBL). Wires can be routinely fabricated with dimensions of 10-20nm wide and (due to the delta doping profile) 1-2 nm in depth. This presentation will briefly introduce high resolution angle resolved photo emission studies on ∂-doped diamond compared to semi-infinite bulk doped diamond, while focusing on the electrical characterisation of the l-dNWs and initial device studies. For example, a diamond side-gated nano-transistor (SG-NT) is proposed and demonstrated for the first time.
2:15 PM - EM06.03.02
Diamond Tip Growth for Magnetometry
Christoph Nebel 1
1 , Fraunhofer IAF, Freiburg Germany
Show AbstractQuantum technology based on diamond requires in nearly all cases ultra-pure layers, with minimized defect densities and isotopically enriched (12C) compositions. For quantum magnetometry, the NV center is very promising due to its unmatched properties. In the literature one can find spin coherence times (T2) up to seconds for NV centers generated deep in the diamond layer. However, for NV centers close to the surface in the range 5 to 20 nm, the spin coherence time constant decreases to typically about 10 microseconds. The reasons for this phenomenon are attributed to surface and near-surface damage generated by mechanical polishing and plasma induced etching. To overcome this limitation one can perform homoepitaxial overgrowth of low defect density diamond layers of typically 1 to 10 micrometer thickness before NV incorporation. The T2 time will increase to properties comparable to the bulk. This technique can offer advantages for devices which require smooth surfaces. Vertical diamond waveguide structures however, which are required for scanning NV-magnetometry, can up-to-now only be produced by plasma etching and are therefore of limited quality.
In this contribution we introduce for the first time a bottom-up technique to generate diamond tips by diamond growth. Firstly, we grow ca. 10 micrometer thick ultra-pure diamond on a [100] diamond seed crystal. Then a Ti mask is deposited, followed by an O2-plasma etching step to form diamond tips of typical 200 nm diameter and ca. 3 micrometer of length (top-down approach). These tips are used to generate a 3D diamond growth around the tips, forming (111) and (100) facets. We use our specifically designed load-lock PECVD reactor which is optimized for the deposition of thin high-quality diamond layers. Dependent on our selected growth parameters we can tune the a-, b- and g-parameters of the growth regime to grow tips with pyramidal shapes either with sharp tips or with (100)-oriented mesas. We will introduce our results in detail based on scanning electron microscopy imaging, atomic force microscopy and a-, b- and g-parameter growth models.
2:30 PM - *EM06.03.03
Nanophotonic Structures Made from Diamond
Wolfram Pernice 1
1 , University of Münster, Münster Germany
Show AbstractOutstanding optical and mechanical properties make diamond a pristine material for applications in photonics and optomechanics. The availability of large area polycrystalline diamond thin films has enabled the use of established nanofabrication methods for realizing advanced integrated photonic circuits for harnessing this potential. I will present a suite of chipscale components which can be used to develop diamond photonic devices with additional mechanical degrees of freedom provided by free-standing nanomechanical resonators. These devices enable all-optically tunable components using gradient optical forces, or also electromechanically tunable components using opto-electro-mechanical resonators. Through the combination with integrated single photon detectors a powerful framework is realized for emerging diamond quantum photonic circuits which can be reconfigured during measurement.
EM06.04: Diamond MOS and Power FETs
Session Chairs
Monday PM, November 27, 2017
Hynes, Level 1, Room 108
3:30 PM - *EM06.04.01
Diamond Power p-FETs Using Two-Dimensional Hole Gas for Complementary High Voltage Inverter
Hiroshi Kawarada 1
1 , Waseda University, Tokyo Japan
Show AbstractDiamond has a variety of stable surface terminations. Among them, the bond enthalpy of C-H is higher than those of C-C or C-O. By altering 1 monolayer, e.g., from C-H to C-O, the electric property changes drastically. The C-H surface is used for the channel and drift region by 2 dimensional hole gas (2DHG) and the C-O surface for device isolation at field effect transistor (FET). The C-H channel and drift of metal-oxide-semiconductor (MOS) FET shows stable normally-on characteristics with 10K-673K after atomic layer deposition (ALD) of Al2O3 at 723K as gate insulator and passivation of drift layer. The p-channel MOSFETs with on-state drain current (ID) density above 100 mA/mm exhibit high breakdown voltages (VB) above 1500V [1] at off-state. Those values are comparable to lateral SiC or GaN power n-channel FETs. By those n-FETs and diamond p-FETs, it is expected a complementary inverter, which simplifies gate drive and surrounding circuits to form an ideal power system. The ID due to 2DHG can be explained by 2 dimensional negative charge sheet [1] near the interface between the Al2O3 and C-H diamond from device simulation. We consider the origin of negative charge sheet responsible for 2DHG is unoccupied states in Al2O3 near diamond interface [1].
For normally-off operation, we have developed two methods. One has been realized by partially oxidized (partial C-O) surface [2], where we can control threshold voltage Vth of FET from normally-on to normally-off (Vth = -5V) by ozone treatment at the center of channel. The high breakdown voltage of VB > 2000V [2] is obtained. More precise control of Vth has been also developed by electrochemical oxidation of diamond surface [3]. The other way has been done by “cascode circuit” configuration, where a normally-off Si p-MOSFET with low VB is connected through its drain to the source of normally-on diamond MOSFET with high VB. Since the gate of diamond MOSFET is grounded, in the zero input (Si FET gate) voltage, a positive voltage between gate and source is automatically applied to keep the diamond FET off-state (normally-off).
Vertical type device having perpendicular conduction path is advantageous for power devices, for high current density. We fabricated vertical-type 2DHG diamond MOSFETs with trench structures [4] by reactive ion etching. The trench side-wall is a regrown homoepitaxial layer for p-channel and p-drift layer. ID-VDS characteristics of vertical-type 2DHG diamond MOSFETs become equivalent [5] to those of lateral diamond MOSFETs by a new connection between the drift layer and highly boron doped p+ substrate (drain).
Overall results show 2DHG diamond MOSFET is approaching to the counterpart of complementary inverter.
[1] H. Kawarada et al. Sci. Rep. 7 (2017) 42368.
[2] Y. Kitabayashi, HK et al. IEEE Elec. Dev. Lett. 38 (2017) 363.
[3] T. Naramura, HK et al. Appl. Phys. Lett. (2017) in press.
[4] M. Inaba, HK et al. Appl. Phys. Lett. 109 (2016) 101063.
[5] N. Oi, HK et al. (submitted).
4:00 PM - *EM06.04.02
Al2O3/O-Diamond Interface for Gate Controlled Diamond Field Effect Transistor
Thanh-Toan Pham 1 2 , Cédric Masante 1 2 4 , Aurélien Maréchal 1 2 4 , David Eon 1 2 , Etienne Gheeraert 1 2 , Nicolas Rouger 3 , Julien Pernot 1 2
1 , University of Grenoble, Grenoble France, 2 , Institut Néel CNRS, Grenoble France, 4 , G2ELab, Grenoble France, 3 , Laplace, Toulouse France
Show AbstractDiamond is widely recognized as the best material for power electronic applications due to its superior physical properties. Diamond Metal Oxide Semiconductor Field Effect Transistor (MOSFET) working in inversion regime (O-terminated diamond 1), or in depletion regime (H-terminated diamond 2) have been realized. In MOSFET devices, the metal-oxide-semiconductor capacitor (MOSCAP) is the critical building block of the device. A complete electrostatic gate controlled of the semiconductor (accumulation, depletion, deep depletion and/or inversion) in MOSCAP test device is critical to realize a MOSFET.
In this context, the O-diamond/Al2O3 MOSCAP test devices have been introduced by Chicot et al 3. The O-diamond/Al2O3 band alignment has been measured by Marechal et al 4. In this work, we introduce a new approach to reduce leakage current and interface states density at O-diamond/Al2O3 interface, which allows a complete electrostatic gate controlled boron doped O-diamond MOSCAP. Then, a new concept for diamond field effect transistor will be introduced and transistor performances will be discussed.
[1] T. Matsumoto, H. Kato, K. Oyama, T. Makino, M. Ogura, D. Takeuchi, T. Inokuma, N. Tokuda, and S. Yamasaki, Sci.Rep. 6 31585 (2016).
[2] H. Kawarada, H. Tsuboi, T. Naruo, T. Yamada, D. Xu, A. Daicho, T. Saito, and A. Hiraiwa, Appl. Phys. Lett 105, 013510 (2014).
[3] G. Chicot, A. Maréchal, R. Motte, P. Muret, E. Gheeraert, and J. Pernot, Appl. Phys. Lett., 102 242108, (2013).
[4] A. Marechal, M. Aoukar, C. Vallee, C. Riviere, D. Eon, J. Pernot, and E Gheeraert, Appl. Phys. Lett. 107 141601 (2015).
4:30 PM - EM06.04.03
Device Simulation of Several C-H MOSFETs Diamond Substrates via Two-Dimensional Negatively Charged Sheet Model
Jorge Buendia 1 , Masanobu Shibata 1 , Mohd Syamsul 1 , Hiroshi Kawarada 1
1 , Waseda University, Tokyo Japan
Show AbstractDiamond based power devices have remarkable potentials based on the highest breakdown field and the thermal conductivity. In this study, diamond MOSFET device simulations have been performed to analyse the characteristic of the 2DHG channel in different diamond substrates i.e. single crystalline diamond, polycrystalline diamonds (mechanical and optical grade) and heteroepitaxial diamond as field effect transistors (FETs) based on fabricated devices [1 – 3].
In previous simulations, the diamond surface channel for MOSFET is reproduced by a model in which acceptors are distributed two-dimensionally on the diamond surface [4]. In our work, we used a 2D fixed negative charge model that induces 2DHG by placing negative fixed charges in the Al2O3/diamond interface instead of acceptor allocation. The structures are similar to the polarization charge generated at the AlGaN/GaN interface in HEMT responsible for the formation of 2DEG from polarization-induced charges [5].
The simulations of the four devices have been modelled based on the experimental IDS-VDS characteristics measured at a drain-source voltage (VDS) of 50 V of 17 μm LGD. The experimental maximum drain current densities were 116, 3.25, 70 and 50 mA/mm for single crystalline, black polycrystalline, transparent polycrystalline and heteroepitaxial diamond respectively normalized with respect to the gate width of 25 μm.
In the off-state, the electric field along the Al2O3/diamond interface decreases with increasing distance from the gate. The electric field distribution along the interface of the devices are evaluated using the simulations for three different high bias and with various mobility values. The simulated electric field distribution along the Al2O3/diamond interface showed a peak (EM) near the gate edge and decreases with increasing distance from the gate edge, the electric field distribution reaches zero at a distance L0 > 10 μm from the gate edge.
These results demonstrate the hole accumulation layer can be simulated by placing fixed negative charges at the Al2O3/diamond interface for single crystalline, polycrystalline and heteroepitaxial diamond MOSFETs. Comparable results with the experimental values of the fabricated diamond MOSFETs characteristics and comparison between them will be presented.
References:
[1] H. Kawarada et al., Sci. Rep. 7, 42368 (2017).
[2] M. Syamsul et al., Appl. Phys. Lett., vol. 109, no 20, 2016.
[3] M. Syamsul et al., IEEE Electron Device Lett., vol. 3106, no c, pp. 1-1, 2017.
[4] K. Tsugawa, H Kawarada et al., Diam. Relat. Mater., 8, 927-933, 1999.
[5] J. M. Tirado et al., Semicond. Sci. Technol., 20, 864, 2005.
4:45 PM - EM06.04.04
Vertical-Type 2DHG Diamond MOSFETs
Nobutaka Oi 1 , Takuya Kudo 1 , Tsubasa Muta 1 , Satoshi Okubo 1 , Ikuto Tsuyuzaki 1 , Taisuke Kageura 1 , Masafumi Inaba 1 2 , Shinobu Onoda 3 , Atsushi Hiraiwa 1 , Hiroshi Kawarada 1 4
1 , Waseda University, Tokyo Japan, 2 , Nagoya University, Nagoya-shi Japan, 3 , National Institutes for Quantum and Radiological Science and Technology, Takasaki-shi, Gunma, Japan, 4 , The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Shinjyuku-ku, Tokyo, Japan
Show AbstractWe fabricated vertical-type diamond MOSFETs with trench structure using two-dimensional hole gas (2DHG) layer for channel. Al2O3 layer has been used for gate insulator [1] [2] and passivation layer [3] on the 2DHG layer on hydrogen terminated diamond surface. In lateral-type device, we reported high breakdown characteristics (~2000 V) [4] [5] and stable operation in wide temperature (10 ~ 673 K) [4]. The 2DHG formed by ALD Al2O3 is independent on crystal orientation, so can be fabricated on the trench side-wall. In this paper, we fabricated vertical-type 2DHG diamond MOSFETs whose current density is 2 orders of magnitude higher than the previous work [6]. Current density and on/off ratio at room temperature (RT) are comparable to lateral-type 2DHG diamond MOSFETs.
Fabrication process was as follows. First, undoped layer was deposited by microwave plasma chemical vapor deposition (MPCVD) and nitrogen-doped layer was formed between undoped layers for blocking leakage current which flows in the direction perpendicular substrate. The concentration of nitrogen-doped layer was ~1019 cm-3. 4 µm depth trench structure was fabricated by inductive coupled plasma reactive ion etching (ICP-RIE). A 200-nm regrowth undoped diamond layer was deposited by MPCVD to cancel surface damages by etching and to form stable 2DHG layer. The gate length was fixed to 4 µm, and the total length between gate and drain, which corresponds to the effective drift length LGD, was ~5µm. We defined the region between gate edge and trench top edges and trench sidewall as the drift region.
The drain current density IDS at VDS of -10 V and -50 V were -49 mA mm-1 and -230 mA mm-1, respectively. The threshold voltage (Vth) was 18.2 V. These values were close to the lateral-type 2DHG diamond MOSFETs with the same channel and drift layer length. In off state, IDS was approximately 10-10 A mm-1 and on/off ratio was ~108. This result indicated that thin nitrogen-doped layer (~50 nm) well blocked substrate leakage current at RT. Measured IDS-VDS curve was reproduced by device simulation based on the two-dimensional negatively charge sheet model [4]. The optimal charge density at the Al2O3/C-H diamond interface was fixed -6.7×1012 cm−2 and carrier mobility at lateral channel and vertical channel at trench structure were 95 cm2/Vs and 47 cm2/Vs, respectively. Operation of vertical-type devices was stable under 473 K and on/off ratio was ~105 at 473 K. We fabricated vertical-type 2DHG diamond MOSFETs, whose characteristics were comparable to lateral-type device.
[1] K. Hirama, H. Umezawa et al. Appl. Phys. Lett., 92(11), 112107 (2008).
[2] M. Kasu, H. Sato, and K. Hirama, Appl. Phys. Express 5, 025701 (2012).
[3] D. Kueck, S. Jooss, and E. Kohn, Diamond Relat. Mater. 18, 1306 (2009).
[4] H. Kawarada et al. Sci. Rep. 7 (2017) 42368.
[5] Y. Kitabayashi, H. Kawarada et al., IEEE Elec Dev Lett, 2261340. pp.363-366 (2017).
[6] M. Inaba, H. Kawaradaet et al., Appl. Phys. Lett. 109, (2016)101063.
EM06.05: Poster Session
Session Chairs
Tuesday AM, November 28, 2017
Hynes, Level 1, Hall B
8:00 PM - EM06.05.01
Diamond MOSFET for RF Application
Biqin Huang 1 , Xiwei Bai 1 , Stephen lam 1 , Kenneth Tsang 1
1 , HRL Laboratories LLC, Malibu, California, United States
Show AbstractDiamond’s potential for high power transistor operating from low frequency to RF domain is extremely attractive, due to its wider band gap and superior thermal conductivity. Diamond transistor as a key component for various applications had been investigated for decades. Several device designs were explored. However, the majority of research is limited by some seemingly daunting challenges, particularly the lack of low activation n type dopant. H terminated surface channel introduces a two dimensional hole layer in diamond, enabling the implementation of diamond field effect transistor. This opened a door to diamond research. Although a lot of progress had been made in this area, the H terminated diamond FET potentially still suffers from low surface mobility. This presentation will explore the alternatives and introduce a non H-terminated diamond transistor. By leveraging the existing diamond technology, this device will explore the full potential of diamond material. The implementation of this device will be demonstrated. The device RF performance will be discussed and the path to further develop the device will be identified.
8:00 PM - EM06.05.02
De-Agglomeration of Detonation Nanodiamond via Salt-Assisted Ultrasonication and Surface Charge Determination Using Advanced Electrochemistry for Sensing Applications
Sanju Gupta 1 , Alex Henson 1 , Brendan Evans 1
1 , Western Kentucky University, Bowling Green, Kentucky, United States
Show AbstractNanoparticles in dry powder state tend to form agglomerates thus reducing surface energy and limiting their technological advancements. Traditional methods such as ultrasonication, ball milling and so on pose significant challenge. In this work, we investigated a facile, cost-effective and contaminant-free technique namely, salt-assisted ultrasonic de-agglomeration of nanodiamond. This technique is expected to prepare single-digit nanodiamond nanoparticles stable colloidal dispersion in a wide pH range from thermally treated nanodiamond and compared with those not treated as control. Utilizing ultrasound energy to break apart nanodiamond aggregates in sodium chloride and sodium acetate salts results in aqueous slurry of single-digit nanodiamond colloids produced by this technique. Since it does not have any toxic or difficult to remove impurities, they are therefore well-suited nanodiamond for numerous applications such as theranostics, composites, lubrication etc. besides scalability. We have structurally characterized these de-aggregated nanodiamond particles using electron microscopy combined with elemental composition, Raman spectroscopy for carbon bonding configurations and scanning electrochemical microscopy for surface charge determination. This work is financially support in parts by NSF KY EPSCoR RSP and NASA KY EPSCOR Awards.
8:00 PM - EM06.05.03
Investigating Titanium Oxide Terminated Diamond as a Low Workfunction Surface for Use in Thermionic Emission
Fabian Fogarty 1 , Paul May 1 , Neil Fox 2
1 , School of Chemistry, University of Bristol, Bristol United Kingdom, 2 , School of Physics, University of Bristol, Bristol United Kingdom
Show AbstractMany applications utilise the emission of electrons for a variety of purposes such as analysing materials, generating x-rays, and even direct power generation. Two kinds of electron emission must be considered here, field and thermionic emission, where the electron emission is induced by an electrostatic field and thermal energy respectively. A thermionic power converter uses this effect to convert heat directly into electrical energy without any moving parts. It consists of a hot cathode that thermionically emits electrons to a cooler anode across a potential barrier, thereby producing electrical power. To make such a device, a surface which is stable at higher temperatures, and emits electrons into the vacuum with relatively little energy loss is required. This can be achieved if the material has a negative electron affinity or low work function.
We will be presenting the XPS, UPS, and NanoESCA results of titanium oxide on different diamond surfaces. In particular the electronic properties and temperature stability of these surfaces.
8:00 PM - EM06.05.04
Tensile Properties of Single Crystal Silicon Microstructure Fully-Coated by Plasma CVD Diamond-Like Carbon with Different Substrate Bias Voltages
Wenlei Zhang 1 , Akio Uesugi 1 , Yoshikazu Hirai 1 , Toshiyuki Tsuchiya 1 , Osamu Tabata 1
1 Department of Microengineering, Kyoto University, Kyoto, Kyoto, Japan
Show AbstractDiamond like carbon (DLC) is an amorphous coating film of good mechanical properties, such as high hardness, toughness and wear resistance. It also has good chemical stability and biocompatibility. Due to good adhesion on silicon surface, DLC film coating would be used in silicon MEMS microstructures for mechanical reliability enhancement and wear resistant improvement. However, characterization of DLC-coated silicon microstructure has not been reported because of difficulties in making specimens for mechanical testing due to its high residual stress and lack of evaluation methods. We have developed full coating process of free standing silicon microstructures to avoid deformation caused by the residual stress and employed electrostatic gripping system for tensile testing and successfully demonstrated improvement of tensile strength [1]. In this report, the effect of substrate bias voltage on DLC coating on tensile properties was investigated to optimize the coating conditions and investigate the mechanism of the improvement.
Specimens for tensile testing were fabricated from silicon on insulator (SOI) wafer with standard fabrication process. The gauge part was 120 μm long, 4 μm wide and 5 μm thick. After releasing from substrate, the specimens were fully coated with 150-nm thick DLC film from the top and bottom side simultaneously by a commercial plasma enhanced chemical vapor deposition (PECVD) machine. Five different bias voltages, from -200 V to -600 V, were examined. Tensile testing of 20 specimens of each condition was conducted using a quasi-static thin film tensile tester using electrostatic gripping system and the measured strength was discussed with the chemical composition and mechanical properties of DLC film.
First, DLC film was characterized by Raman spectroscopy, wafer curvature measurement and nanoindentation. The Raman spectrum suggested the decrease of sp2 phase and hydrogen content and increase of sp3 phase by the increase of bias. The residual stress, elastic modulus and hardness increased by increasing the bias, which corresponded well to the Raman analysis. The fracture toughness evaluated by nanoindentation was 1.4-2.2 MPam1/2 and the maximum toughness was obtained at -400 V bias.
The tensile strength of the DLC coated single crystal silicon specimen was 13.2%-29.6% higher compared to the bare silicon sample. The -400 V bias showed the highest strength of 3.94 GPa, which was in a very good agreement with fracture toughness of DLC. The two-parameter Weibull analysis revealed that the Weibull modulus increased by DLC coating. Moreover, the modulus increased by increasing the bias. Since it was reported that DLC film had large compressive residual stress and the stress was higher at the film surface than near the film/substrate interface, the stress may prevent the crack propagation and make the strength insensitive to the initial flaw size.
[1] W. Zhang, et al., Jpn. J. Appl. Phys. 56, 06GN01, 2017.
8:00 PM - EM06.05.05
Fundamentals for Identification of 1Cs X-Ray Photoelectron Spectroscopy (XPS) Peaks Related to Sp2 and Sp3 Carbon Atoms Bonds in Crystalline Diamond and Diamond Films
Jean Veyan 1 , Elida De Obaldia 2 1 , Jesus Alcantar-Peña 1 3 , Jorge Montes 3 , Orlando Auciello 1
1 , The University of Texas at Dallas, Richardson, Texas, United States, 2 Facultad de Ciencias y Tecnologia, Universidad Tecnologica de Panama, Panama, Panama, Panama, 3 Departamento de Física, Universidad de Sonora, Hermosillo, Sonora, Mexico
Show Abstract
The identification of the C1s peak location in the X-Ray Photoelectron Spectroscopy (XPS) spectra produced when analyzing crystalline diamond and diamond thin films have been intensively studied during recent decades. A key aspect of all these studies is the identification of the XPS peaks that characterize the sp2 and sp3 C atoms bonds in the diamond under analysis, whether in a crystalline diamond, where the sp2 bonds may arise from adventitious carbon adsorbed on the surface, or microcrystalline diamond films, where the sp2 bonds may arise from either adventitious carbon on the surface or sp2 dangling bonds in the grain boundaries. A typical procedure to produce a clean diamond surface in XPS analysis involves bombarding the surface with a low energy (0.5-3 keV) Ar ion beam. Because lack of explicit information, it is not clear from many XPS studies of diamond, published in the literature, whether Ar ion bombardments was used to clean the surface of the diamond. Thus, it is not clear whether the slight shift in binding energy for the peaks identified as corresponding to sp3 vs sp2 bonds, arise from Ar ion bombardment used to clean the samples. Therefore, the research discussed in this paper was focused on performing a systematic series of experiments to investigate the location, in binding energy, of the XPS C1s peaks after bombardment with Ar ions. The XPS studies involved analysis of single crystal diamond, and microcrystalline diamond (MCD, 1-3 µm grain size), nanocrystalline diamond (NCD, 10-100 nm grain size) and ultrannanocrystalline diamond (UNCD, 3-5 nm grain size) and graphite films, which exhibit substantially different sp3 C atom bonds, characteristic of diamond and sp2 C atoms bonds, characteristic of graphite or dangling bonds in polycrystalline diamond grain boundaries. The studies discussed in this paper focused on investigating the effect of Ar ion bombardments during XPS analysis to determine the chemical bonds changes as a function of Ar ion implantation observed after bombardment. Our findings suggest that the C 1s peak appearing at high binding energy, which is usually reported in the literature as associated with the sp3 C atoms bonding, characteristic of diamond, appears to arise from a different state of the sp3 bond in diamond after Ar ions have been implanted in the diamond. The analysis of the XPS spectra from the diamond films indicate that the Ar+ ion bombardment does not affect the sp2 C atoms bonding, characteristic of the graphite structure, but which are related to dangling sp2 bonds in grain boundaries. Furthermore, RBS analysis revealed that Ar atoms are inserted in the material and they are not expelled even after annealing up to about 600-700 C. In addition, XRD analysis revealed the presence of a new peak, which appears to be related to the effect of the incorporated Ar atoms inside the diamond lattice inducing crystallographic changes.
8:00 PM - EM06.05.06
Polishing of Thin Diamond Films for Micro-Electromechanical Applications
Soumen Mandal 1 , Evan Thomas 1 , Joshua Green 1 , Emmanuel Brousseau 1 , Oliver Williams 1
1 , Cardiff University, Cardiff United Kingdom
Show AbstractMicro-electrical mechanical systems incorporate the actuation, perturbation, and sensing of micron level mechanical devices within electronic circuits. They can be used to detect mass1, force2 and displacement. Ultra-sensitive detection of these parameters is important for many bio-medical applications3,4. Apart from ultra-sensitive nature of detection it is important to have the detectors made out of materials which are bio-inactive, making diamond an excellent candidate for such devices due to its bio-compatibility5. While thin film diamond can be grown in both single-crystal and polycrystalline forms, the retention of many of the properties of bulk diamond and possibilities of large area deposition make nano-grained nanocrystalline diamond (NCD) a viable alternative. However, the downside of the NCD is the inherent surface roughness that comes due to its growth mechanism6. Palasantzas7 have shown that surface roughness in a mechanical devices can lead to reduced sensitivity. To get around this problem we have developed a chemical mechanical polishing technique capable of generating smooth diamond surfaces, however the rate of polishing is extremely slow (20nm/h). In this work, we explore the effects of addition of strong oxidizing agents to the polishing fluid on the roughness reduction rate of diamond films.
A series of diamond films were grown on silicon dioxide buffered silicon using CVD. The films were polished for four hours and the roughness monitored by atomic force microscopy after each hour of polishing. The base slurry for polishing was colloidal silica based SF1 from Logitech. The slurry could reduce a nominal roughness of ~24nm RMS on as grown diamond films to ~2nm RMS over 25 µm2 within four hours of polishing. The same slurry with trace amounts of Fe(NO3)3 or KMnO4 could polish the films to ~2nm RMS roughness with just 2 hours of polishing clearly indicating an increased polishing rate. Similar enhancement was not seen for slurry with hydrogen peroxide.
References
1 K. Jensen, K. Kim, and A. Zettl, Nat. Nanotechnol. 3, 533 (2008).
2 J. Moser, J. Güttinger, a Eichler, M.J. Esplandiu, D.E. Liu, M.I. Dykman, and a Bachtold, Nat. Nanotechnol. 8, 493 (2013).
3 K.J. Rebello, Proc. IEEE 92, 43 (2004).
4 S. Bhansali and A. Vasudev, editors , MEMS for Biomedical Applications (Woodhead Publishing Limited, Sawston, Cambridge, UK, 2012).
5 L. Tang, C. Tsai, W.W. Gerberich, L. Kruckeberg, and D.R. Kania, Biomaterials 16, 483 (1995).
6 O.A. Williams, Diam. Relat. Mater. 20, 621 (2011).
7 G. Palasantzas, Appl. Phys. Lett. 90, 1 (2007).
8:00 PM - EM06.05.07
Sensing Endocrine Disrupting Chemicals by Virus-Based Structural Colour Nanostructure
Yujin Lee 1 , Jong-Sik Moon 2 , Jiye Han 1 , Jin-Woo Oh 3
1 Nano Fusion Technology, Pusan National University, Busan Korea (the Republic of), 2 BK21 PLUS Nano Convergence Technology Division, Pusan National University, Busan Korea (the Republic of), 3 Department of Nanoenergy Engineering, Pusan National University, Busan Korea (the Republic of)
Show AbstractThe adverse effects of endocrine disrupting chemicals (EDCs) has attracted considerable public interests. The benzene like EDCs structure mimics the mechanisms of hormones naturally occurring in vivo, and alters physiological function of the endocrine system. Although, some of the most representative EDCs such as polychlorinated biphenyls (PCBs) and phthalates compounds already have been prohibited to produce and use in many countries, however, PCBs and phthalates in plastic products as flame retardant and plasticizer are still circulated nowadays. EDCs can be released from product while using and discarding, and it causes serious environmental and health issues. Here, we developed virus-based structurally coloured nanostructure that can detect minute EDCs concentration sensitively and selectively. These structurally coloured nanostructure exhibits characteristic angel-independent colors due to the regular virus bundle structure formation through simple pulling technique. The designed number of different colour bands can be formed through controlling concentration of virus solution and pulling speed. The virus, M-13 bacteriophage, was genetically engineered to react with specific ECDs, typically PCBs and phthalates. M-13 bacteriophage surface (pVIII major coat protein) was decorated with benzene derivative binding peptides (WHW) through phage library method. In the initial assessment, virus-based color sensor was exposed to several organic chemicals including benzene, toluene, phenol, chlorobenzene, and phthalic anhydride. Along with the selectivity evaluation of virus-based colour sensor, it also been tested for sensitivity. 10 to 300 ppm of phthalic anhydride and chlorobenzene were detected by colour sensor, and showed the significant sensitivity with about 90 of dissociation constant. Noteworthy, all measurements were analyzed through principal component analysis (PCA) and linear discrimination analysis (LDA), and exhibited clear discrimination ability upon exposure to 2 categories of EDCs (PCBs and phthalates). Because of its easy fabrication, high sensitivity, and the superior selectivity, M-13 bacteriophage-based color sensor could be a simple and reliable portable sensing system for environmental monitoring, healthcare, social security, and so on.
8:00 PM - EM06.05.08
Selective Formation of Single-Crystalline Diamond on Si Substrate by Epitaxial Lateral Over Growth
Hideo Isshiki 1 , Yuki Saito 1 , Keisuke Ino 1
1 , University of Electro-Communications, Tokyo Japan
Show Abstract
Highly oriented diamond nucleation and selective diamond growth on a Si substrate are demonstrated by using bias-enhanced nucleation (BEN) accompanying with atomic Si. Due to the background of energy saving and environmental problems in recent years, next generation power devices applying excellent electrical characteristics of diamond have been expected. In general, nucleation process preceding crystal growth is determined by competition between cohesive energy (formation of three-dimensional structure) and interface energy (formation of planar structure). In the case of carbon crystallization, sp2 hybridization exists in stable relatively, so the cohesive energy cannot well exceed the interface energy and it becomes easy to form planar graphite before the diamond nucleation. In BEN process, it is considered that amorphous carbon (a-C) aggregates on the substrate surface by the negative bias and then the critical diamond nuclei spontaneously generate. The important point is considered to be how to increase cohesive energy overcoming the interface energy. In 2012, we found that the addition of a small amount of atomic Si to BEN process promotes the generation of oriented diamond nuclei on Si substrate.
In experiment, microwave plasma enhanced chemical vapor deposition (MP-CVD) was used for diamond nucleation and growth. BEN process was performed on silicon substrates, and hydrogen diluted mono-methyl silane (MMS: Si(CH3)H3) was used as an atomic silicon source during BEN process. The nucleation density estimated by the SEM photograph increases lineally with increasing the total amount of MMS supply. The grown diamond without MMS shows random facets, however that with MMS exhibit homogeneous crystalline planes oriented to <011> direction of Si substrate. It seems that atomic Si attaches on the substrate surface and becomes the nucleation center, thereby efficiently forming oriented diamond nuclei.
Two-step growth for the diamond selective formation on Si (100) substrate was performed by MP-CVD. The first process is the highly oriented BEN described above. The second step is the epitaxial lateral over growth (ELOG) of diamond. High microwave power enhances desorption of carbon species from Si surface, thereby suppressing the spontaneous diamond nucleation and the regrowth on Si surface. The ELOG diamond exhibits an isolated single-crystalline diamond cube with the device size (80-μm square) oriented to Si (100) substrate. Micro-Raman scattering spectrum of the diamond cube shows a peak at 1333-cm-1 with linewidth of 4.5-cm-1 indicating good crystallinity equivalent to homo-epitaxial diamond.
We have successfully realized selective growth of crystalline diamond with the device scale on a Si substrate. This is an important progress toward heterogeneous integration of the diamond power device on Si LSI chip for the future power electronics, such as highly intelligent power module (IPM).
8:00 PM - EM06.05.09
Diamond Energy Levels and Photoemission Characteristics from 300 – 425K
Susanna Challinger 1 , Iain Baikie 1 , Glen Birdwell 2
1 , KP Technology, Wick United Kingdom, 2 , U.S. Army Research Laboratory, Adelphi, Maryland, United States
Show AbstractThe unique electronic structure of diamond and its excellent thermal properties allow a broad range of possible applications; from electron sources to RF electronics. However, knowledge of the surface energy levels is essential to produce efficient, high-quality devices.
We investigate the valence band position and resulting negative electron affinity for hydrogen terminated diamond under ambient, low vacuum and ultra-high vacuum (UHV) conditions. There was a -0.5 eV change in valence band position causing a negative electron affinity shift from -1.1 eV under UHV to -0.6 eV in ambient pressure. We compare the photoemission current under each environment to predict the ability of the sample to be used as an electron source. The maximum emission was observed when the sample displayed the largest negative affinity. A scanning photoemission measurement is demonstrated to highlight the superior photoemission yield from the hydrogen terminated diamond surface compared to the stainless steel contact. A scanning Kelvin probe measurement is shown to illustrate a method of analysing the contact potential difference across the diamond surface.
Within high-power RF electronics, devices are likely to be operating at increased temperatures so knowledge of the impact of temperature on the energy levels is important. We study the valence band and fermi level positions for hydrogen terminated diamond from room temperature (300K) to 425K under low and UHV conditions. The Fermi level moved below the valence band edge at increased temperature, illustrating the effect of the 2D hole gas at the surface. We also analysed the photoemission characteristics and found an increase in yield with increasing temperature.
The measurement techniques used to evaluate the energy levels of diamond: photoemission spectroscopy and Kelvin probe measurements, in ambient and vacuum, allow analysis to be completed in minutes. This offers an initial analysis alternative to elucidate more information and predict performance prior to the more time-consuming full device manufacture and characterisation.
8:00 PM - EM06.05.10
High Growth Rate CVD of Selectively Aligned Ensemble NV Centers
Takeyuki Tsuji 1 , Hayato Ozawa 1 , Junya Yaita 1 , Takayuki Iwasaki 1 , Mutsuko Hatano 1
1 , Tokyo Institute of Technology, Tokyo Japan
Show Abstract
Nitrogen-vacancy (NV) center in diamond is considered as excellent solid-state magnetometers which can operate at room temperature. For improvement of the magnetic sensitivity, three factors such as the large number of NV center contributing the magnetic detection, control of orientation of NV axes toward one direction, and long spin coherence time T2 must be satisfied. We have developed perfectly aligned NV ensemble (NV density=4 × 1016 cm-3) by microwave plasma chemical vapor deposition (MPCVD) on (111) diamond substrates [1] and the step-flow growth is the key for the selective alignment. However, only the low growth rate CVD condition (<0.5 µm/h) introduced the step-flow growth because of the low plasma power density (80 W/cm3). To achieve higher sensitivity (< pTHz-1/2) for the macroscale applications such as measurement of heart and brain, large volume with a thick CVD films are needed. In addition, the NV generation efficiency (NV/N ratio) was as low as 0.4 %, and the spin coherence time T2 was limited to 2 µs by the high concentration of electronic spins in surrounding N atoms.
In this study, we utilized MPCVD with higher plasma power density (520 W/cm3) to obtain high concentration of diamond precursors and atomic hydrogens. Therefore we can introduce step-flow growth at high CH4 concentration (0.2%). Consequently, we obtained a higher growth rate and longer T2 while achieving the selective alignment.
The diamond film was grown on a Ib (111) substrate with an off-direction toward [-1-12] and an off-angle of 2° for the selective alignment of the NV axes [2]. A gas mixture of CH4/H2 (0.2%) was used as source gases. N2 gas was introduced (N/C =8%) to form NV ensemble. Microwave power, gas pressure, and temperature were 600 W, 30 kPa, and 950 °C, respectively. The growth rate estimated by cross section of confocal microscope observation was 8 µm/h. Selectivity of the NV axis alignment along the [111] direction was about 80 % confirmed by optically detected magnetic resonance measurement. The NV density estimated using an intensity of single NV center was about 6 × 1016 cm-3, almost same as our previous report [1]. We obtained a higher T2 of 6.9 µs, which is 3 times longer than that with the low plasma power density. In general, T2 is inversely proportional to the N concentration [3]. Thus, the longer T2 obtained here suggests that NV/N ratio would also become higher with high plasma power density. We found that the high plasma power density is effective to meet the requirements mentioned above (large sensor volume, selective alignment, and long T2) toward realizing room-temperature high sensitive magnetometers.
Acknowledgements
This work was supported by CREST, JST and JSPS KAKENHI Grant (No. JP17H01262)
[1] H. Ozawa, et al. Applied Physics Express 10, 045501 (2017).
[2] K. Tahara, et al. Applied Physics Letter 107, 193110 (2015).
[3] Z. H. Wang, et al. Physical Review B 87, 115122 (2013).
8:00 PM - EM06.05.11
Electronic Structure of TM-Related Centers in Diamond—A Density Functional Theory Analysis
Kamil Czelej 1 , Piotr Spiewak 1 , Krzysztof Kurzydlowski 1
1 Materials Science and Engineering, Warsaw University of Technology, Warsaw Poland
Show AbstractDiamond offers a defect centers that could possibly act as quantum bits in quantum information processing at room temperature. Specifically, the nitrogen-vacancy (NV) and the silicon-vacancy (SiV) complexes have been vastly investigated both, theoretically and experimentally. The transition metal (TM) related complexes in diamond, such as TM-V may be another interesting candidates in various quantum information processing applications, due to their unique electronic structure, nonzero spin ground state and possible optical excitations. However, relatively small amount of information about these complexes have been reported so far. To fill the gap we carried out a systematic study of selected TM-related centers in diamond using spin-polarized, hybrid density functional theory approach. The revised Heyd-Scuseria-Ernzerhof screened hybrid functional (HSE06) was applied for the total energy calculation. For each defect the equilibrium geometry, formation energy as a function of charge state, excitation energy, net spin and defect charge transition levels were determined. On the basis of formation energy vs Fermi level diagrams, relative stability of different charge states was predicted. The group theory analysis together with the calculated K-S singe particle energies were used to describe the defect states for the selected TM-related complexes. Finally, possible excitations of the defects analysed were determined and subsequently discussed in terms of their usefulness as a color centers. Our theoretical results provide a valuable information on TM-related complexes and may be useful in identification of unknown TM-related centers in diamond from the experimental data.
8:00 PM - EM06.05.12
AC Susceptibility of Thin Diamond Films
Jessica Werrell 1 , Georgina Klemencic 1 , Soumen Mandal 1 , Sean Giblin 1 , Oliver Williams 1 , Laia Gines 1
1 , Cardiff University, Cardiff United Kingdom
Show AbstractAlternating current (AC) magnetic measurements, in which an AC field is applied to a sample and the resulting AC moment is measured, are an important tool for characterizing many materials. A fundamental property measured by this technique, both AC and direct current (DC), is the susceptibility of the material. The use of an AC field yields greater information about the sample’s magnetization dynamics; this is often described in terms of the susceptibility having an in-phase, or real, component χ' and an out-of-phase, or imaginary, component χ". This study uses AC magnetic measurements to examine the χ' and χ" of a series of chemical vapour deposition (CVD) grown boron-doped nanocrystalline diamond (B-NCD) thin films. B-NCD thin films being superconductors means χ' and χ" represent measures of flux exclusion due to induced shielding currents and magnetic losses due to the movement of flux lines, respectively. The samples were grown under identical conditions with only their grain size varying as a result of changing the film thickness. The AC magnetic response of the samples was measured using a Quantum Design Physical Properties Measurement System.
8:00 PM - EM06.05.14
NV-Electrochemical DNA Biosensor Based on Charge State of NV Centres in Diamond on Microfluidic Device
Milos Nesladek 1 , Maria Krecmarova 2 , Thijs Vandenryt 2 , Emilie Bourgeois 1 , Ronald Thoelen 1
1 , imec Leuven and Hasselt University, Diepenbeek Belgium, 2 Institute for Materials Research, Hasselt University, Hasselt Belgium
Show AbstractWe present a novel concept of biomolecular sensors based on operation of quantum colour centres in diamond integrated on a microfluidic biosensor. The developed device is based on a combination of NV centre optical readout combined with an electrochemical device. By this way the device can lock on an electrochemical potential specific for particular reactions and to use the NV centre charge state for detection of specific chemical reaction products. The device is covered by polydimethylsiloxane flow cell and transparent indium tin oxide coated glass slide. Switching of the NV-/NV0 centre population is detected by photoluminescence (PL). We set first the charge state occupation of NV centre by applying a bias voltage between source and gate electrode. The charge state of NV centres then react to electrochemical potential of the environment. To demonstrate the label free optical detection the diamond surface is covered with a monolayer of strongly cationic charged polymer polyethylenimine (PEI) that modify the charge state of near surface NV centres to NV0 or NV+ non-PL state. Immobilization of the negatively charged DNA molecules on the sensor surface changes the NV centres charge states to preferably NV- and the PL is detected by confocal microscopy.
8:00 PM - EM06.05.15
Classification of the Different Dynamic Behaviors of Pulsed Microwave Discharges Utilizing the Ton-Toff Space
Matthias Muehle 1 2 , Jes Asmussen 2 , Michael Becker 1 , Qi Hua Fan 2 , Thomas Schuelke 1 2
1 , Fraunhofer USA, Center for Coatings and Diamond Technologies, East Lansing, Michigan, United States, 2 Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan, United States
Show AbstractPulsing of microwave discharges is of great interest for the growth of single crystalline diamond (SCD). Numerical calculations suggest, that a proper utilization of pulsing can alter the gas temperature favorably in order to promote a higher generation of [CH3] species, which in turn will result in higher SCD growth rates [1]. Significant growth rate increases have been demonstrated [1,2]. However, the explanation of the increase in growth rate is based on static models and does not include the dynamic nature of the formation and development of a pulsed microwave discharge. For example, high speed video recording of the pulsed discharge cycle revealed a highly dynamic behavior within the discharge region of the reactor [3]. Those dynamics cannot be described by currently established models. It also showed, that the on-time Ton and the off-time Toff of the pulsing cycle are the fundamental parameters to describe pulsed discharges, instead of the pulsing frequency and the duty cycle, which are commonly used, but are dependent on Ton and Toff.
There is a clear need to utilize new analytical tools to accurately record the development of pulsed discharges so that numerical models can be updated in order to reflect those phenomena and their effects on the species distribution over time. Those techniques include high speed video imaging and optical emission spectroscopy. For example, the use of high speed video imaging revealed a total of six different behaviors of the discharge under pulsed conditions when varying Ton and Toff. Then, the two-dimensional Ton-Toff space was used to illustrate the presence of the different pulsing patterns within this multi-variable parameter space. The Ton-Toff space also contains continuous wave excitation, which is located on the Ton axis and the case of no microwave excitation (on the Toff axis). This showed, that moderate and high Toff times (>3ms) always result in an arc-like ignition of the discharge right on the SCD substrate. The shape of the discharge matches the distribution of the electric field inside the reactor without the presence of a discharge. On the other hand, short Toff times result in a sufficient number of active species remaining in the discharge region due the lower amount of species recombination. This impacts the electric field distribution of the reactor. As a result, the discharge is igniting separated from the SCD substrate.
Proper mapping of those effects and identifying the reasons causing them is of significant importance for the efficient use of pulsed discharges. These information is utilized for a more accurate description of the dynamic behavior of pulsed discharges and the setup of experimental designs, which are optimized for pulsed conditions.
References
[1] Brinza et al., physica status solidi (a) 204 (2007), 2847-2853
[2] Muchnikov et al., Diamond and Related Materials 20 (2011), 1225-1228
[3] Muehle et al., ICDCM 2016
8:00 PM - EM06.05.16
Modelling of NV Diamond Quantum Chip with Electrical Readout of Spin States
Milos Nesladek 1 , Jaroslav Hruby 1 , Emilie Bourgeois 1 , Josef Soucek 1 2
1 , imec Leuven and Hasselt University, Diepenbeek Belgium, 2 Biomedical Engineering, Czech Technical University, Kladno Czechia
Show AbstractHybrid photoelectric readout of NV spin states opens important promises for developing scalable NV diamond quantum chips for room temperature operation. Here we present a detail modeling of photoelecric quantum chip
using all device components and incorporating MW antenna design, electrode layout configuration as well as laser light profile. Further on, based on solving the rate equations combined with the expression for 2 –photon and 1-photon ionization and the laser power density we discuss the chip operation performance as well as S/N ratio for quantum readout operation.
8:00 PM - EM06.05.17
Low-Cost Metamaterial-on-Paper Chemical Sensor
Aydin Sadeqi 1 , Hojatollah Rezaei Nejad 1 , Sameer Sonkusale 1
1 , Tufts University, Medford, Massachusetts, United States
Show AbstractWe present a disposable low cost paper-based metamaterial for sensing liquids based on their dielectric properties. The sensor is based on resonance shift due to the change in the effective capacitance of each resonator in the metamaterial array. Key novelty in the design is the implementation of metamaterial on low cost and ubiquitous paper substrate. This metamaterial-on-paper sensor is fabricated in a totally cleanroom-free process.
The paper chosen as a substrate is chromatography paper which has been wax printed by a wax printer, making wax-printed hydrophobic and hydrophilic stripes. After wax printing, the substrate was heated so that wax can penetrate to the other side of paper, creating an impenetrable zone for any liquids. Such wax based patterning of paper enables creation of microfluidic channels through the non-wax regions that are hydrophilic causing liquid analytes to be routed using natural capillary actions to any desired regions on the substrate, which in our case would be the capacitive gaps of each resonator in the metamaterial array. A stencil mask with periodic design of circles corresponding to the resonator unit cells, were cut on a polyimide tape by using CO2 cutter. It is then adhered on to the substrate paper and aligned onto the waxed region of the paper next to the microfluidic. After adhering polyimide sheet on wax-printed paper, the whole space was painted by silver ink. Then, polyimide sheet was peeled off the paper leaving behind circular shapes of conductive silver parts on waxed areas, which serves as our disk resonators. The unit cells of the metamaterial have length of 3 mm and disks are 1 mm in diameter. The device is fabricated with the dimensions of 11.5×11.5 cm2.
We used CST Microwave Studio® to simulate performance of the device. On the other hand we extracted experimental data using a continuous wave terahertz spectrometer. We characterized transmission spectrum using continuous wave (cw) THz spectroscopy system, TeraScan 1550 by sweeping between 50 and 150 GHz with spectral resolution of 200 MHz.
We tried different liquid analytes with a wide range of permittivity for sensing, including oil, methanol, Glycerol and water with relative permittivity of 3.1, 33.1, 57 and 80.4 respectively. Transmission spectrum of the metamaterial shows drastic change of 11 GHz when water flows through microfluidic channels. By applying this method we could distinguish the analytes by the shift imposed on the resonance frequency. It appears, resonance frequency shift has a linear trend since dielectric constant of the chemical rises. The samples showed resonance frequency between 91 and 96 GHz and the mean value of resonance frequency shift for oil, methanol, glycerol and water were 1.12, 4.12, 8.76 and 11.63 respectively showing an average shift of 0.138 GHz per unit of relative permittivity.
8:00 PM - EM06.05.18
Electronic Dependence on Hydrogen Concentration and Grain Size Effects of Polycrystalline Diamond Films as Alternative to Crystalline Diamond Films on Si Substrates for Fabrication of Diamond-Based Diodes for Electronic Power Devices
Jesus Alcantar-Peña 2 1 , Gerardo Gutierrez-Heredia 2 , Ali Behroozfar 3 , Diego Barrera 2 , Elida De Obaldia 2 , Yuriy Kudriavtsev 4 , Majid Minary 3 , Julia Hsu 2 , Walter Voit 2 3 , Dainet Berman-Mendoza 1 , Orlando Auciello 2 5
2 Material Science, University of Texas at Dallas, Richardson, Texas, United States, 1 Physics Research, Universidad de Sonora, Senora Mexico, 3 Mechanical Engineering, University of Texas at Dallas, Richardson, Texas, United States, 4 Electrical Engineering , CINVESTAV-IPN, D.F., D.F., Mexico, 5 Bioengineering, University of Texas at Dallas, Richardson, Texas, United States
Show AbstractIn this work, we present the research on growing polycrystalline diamond films and integrating them with complimentary materials to fabricate and characterize the electrical performance of Schottky diodes. The hydrogenated diamond surfaces can facilitate applications for electronic power devices as an alternative to current commercial silicon and exploratory single crystal diamond-based devices. Growth of polycrystalline diamond films with large grain size on Si substrates exhibiting high thermal transport (~ 1500 W/Km), high mobility (210 cm2/V.s) and promising sheet carrier concentration (6.5 x 1013 1/cm2). These properties may provide diamond-based diodes with high heat sink thermal layers for fabrication of high performance next generation micro/nano electronic power devices on diamond films integrated on large area silicon wafers. The demonstrated multi functionalities of polycrystalline diamond films on silicon substrates may enable applications as active layer on semiconductor devices, and as heat sink layers in electronic devices. In this presentation, we will report advances on the electrical properties of polycrystalline diamond films grown on Si substrates with different hydrogen concentration and grain size from ~6 nm up to ~3 µm. Polycrystalline diamond films were grown on silicon substrates, using hot filament chemical vapor deposition (HFCVD). Also, Schottky diodes were fabricated on diamond films surface. Small grain size diamond films were grown using Ar-rich/CH4/H2 chemistry, while large grain size films were grown using the H2-rich/CH4 chemistry. Electrical conduction trough the grain boundaries of the films were measured using Conductive AFM and Kelvin probe AFM methods, while electrical performance was measured on Schottky diodes fabricated on the surface of the diamond films. In addition, Secondary Ion Mass Spectroscopy (SIMS) studies revealed the hydrogen concentration change respect to the grain size and gas mixture used to growth the films. X-ray Photoelectron Spectroscopy, Ultraviolet Photoelectron Spectroscopy (UPS), Kelvin probe and Photoemission Spectroscopy in air (PESA) were used to study the hydrogen concentration and grain size effect on the band diagram of the different films. Raman spectroscopy (532nm wavelength) was used to study the bonds related to the grain boundaries, as well as Scanning Electron Microscopy (SEM) to see the morphology changes. The modulation of the electrical properties, via grain size and hydrogen concentration of the polycrystalline films allows to have electrical performance like crystalline diamond-based Schottky diodes. Contrary to single crystal diamond grown only on small area crystalline diamond substrates, polycrystalline diamond films can be grown on 300 mm diameter wafers with excellent uniformity. Our results present a pathway to overcome the single crystal diamond technology and accelerate practical applications on micro/nano-electronic power devices.
8:00 PM - EM06.05.19
Diamond-Gold Hybrid Nanostructure for Cell Studies Applications
Seidy Pedroso-Santana 1 , Noralvis Fleitas-Salazar 1 , Jose Andre-i Sarabia-Sainz 1 , E. Silva-Campa 1 , A. Angulo-Molina 2 , B. Castaneda 1 , Rodrigo Melendrez-Amavizca 1 , Raul Riera 1 , Martin Pedroza-Montero 1
1 Departamento de Investigacion en Fisica, Univ of Sonora, Hermosillo, Sonora, Mexico, 2 Departamento de Químico Biólogo, Universidad de Sonora, Hermosillo, Sonora, Mexico
Show AbstractUsing detonation nanodiamonds and fluorescent NV-centers nanodiamonds, linked to gold nanoparticles, we synthesized two hybrid nanostructures (HGD) that were subsequently conjugated with a fluorophore. The antenna effect produced by gold nanoparticles increased the emission spectrum of the fluorophore maximizing possibilities for imaging applications of these HGDs. The incubation of the nanostructures with HeLa cells produced no alteration of cells viability after 3 h, and showed the presence of the nanostructures into the cell cytoplasm after 24 h. These observations also indicate the potential biomedical use of the proposed HGDs.
8:00 PM - EM06.05.20
Fluorescent Nanodiamonds as Nanothermometers for Biological Applications
J. Ramirez-Hernandez 1 , M. Acosta-Elias 1 , E. Silva-Campa 1 , Jose Andre-i Sarabia-Sainz 1 , A. Burgara-Estrella 1 , A. Angulo-Molina 1 , B. Castaneda 1 , Sofia Navarro-Espinoza 1 , Diego Soto-Puebla 1 , K. Santacruz-Gomez 1 , Marcelino Barboza-Fores 1 , Martin Pedroza-Montero 1
1 , Universidad de Sonora, Hermosillo Mexico
Show AbstractNanodiamonds have been recently studied for several applications in biological sciences due to their inherent biocompatibility and low cytotoxicity. Other investigations have shown perspectives in their use as nanothermometers with slight insights on the dependence of their optical properties with temperature. Precise localized temperature sensing is needed in a vast variety of scientific fields. In our work, we present how the emission spectra of detonation nanodiamonds (DND) change with temperature within a biologically important range (25-60C), and nanothermic scales were obtained for the samples from the Zero-Phonon Line (ZPL) of N-V centers. These scales represent a first approach for a direct reading of localized temperature of cells and other biological systems using nanodiamonds.
8:00 PM - EM06.05.21
X-Ray Tomography and Fracture—Diamond Materials and Devices
Dong Liu 1 2 , Martin Kuball 2
1 , University of Oxford, Oxford United Kingdom, 2 , University of Bristol, Bristol United Kingdom
Show AbstractDiamond materials (both single crystal and polycrystalline) have thermal properties uniquely beneficial for heat-sinking applications, due to their ultra-high thermal conductivity. Potential applications include GaN-on-diamond microwave technology for replacement of GaN-on-SiC devices or simply heat spreading diamond plates integrated with various III-V and Si technologies. What is critically important is to gain a non-destructive microstructural assessment of the diamond materials (as it affects heat-sinking capability of the diamond), and equally to understand interfacial strength between the diamond and different materials, such as to metal layers (to ensure a reliable technology is feasible).
In the present work, an X-ray computed tomography (XCT) technique has been utilized to gain a critical 3D vision of diamond materials, the interfaces between the diamond and a dissimilar material such metals when they are integrated together to form devices. A sub-micrometer resolution was achieved using XCT and we will demonstrate the distribution of defects inside these structures in a 3D space. In addition, XCT was used for the detailed assessment of via holes in the diamond needed to achieve micro-strip microwave technology. Potential graphitization was observed on the inside wall of these via holes and the graphite layer has been quantitatively characterized to enable the minimization of this unfavored layer. Based on the 3D visualization of the microstructure of the devices, in situ micro-mechanical testing was used to assess the local interfacial strength. The experimental setup includes an in situ loading probe housed inside a scanning electron microscope that permits the fracture being observed as the device was deformed. Subsequently, an ex situ nano-indenter was utilized to investigate the macro-scale delamination and fracture of these devices. The results are discussed with respect to the strategies for producing a strong interfaces of diamond to different metallizations which is crucial for a reliable device technology.
8:00 PM - EM06.05.22
Future Diamond MOSFETs for Power Electronics
Philippe Bergonzo 1 , Etienne Gheeraert 2 , Julien Pernot 2 , Alex Pakpour-Tabrizi 3 , Richard Jackman 3
1 , CEA, LIST, Diamond Sensors Laboratory, Gif-sur-Yvette France, 2 , Neel Institute, Grenoble France, 3 , The London Centre for nanotechnology, London United Kingdom
Show AbstractWithin its supportive action under program H2020, Europe has recently granted support to the GREENDIAMOND project, that gathers 14 partners towards the development of single crystal diamond structures aiming a the fabrication of a MOSFET power converter. Based on the recent demonstration of a MOS structure fabricated on diamond1, the consortium aims at assembling of a complete transistor to be used in high voltage applications: target prototypes aim at devices compatible with 6.5kV and 10kV operating voltages.
The project ultimately aims at the fabrication of high voltage converters that overtakes Si, SiC and GaN transistor performances in terms of high voltages and current densities, and compatible with harsh operating environments. The prototypes to be developed aim at high temperature operations (<250°C) and high switching capabilities (5kHz). The project started on May 2015 for a duration of 4 years. This poster will describe the context, the consortium, and the project objectives.
1 G. Chicot et al, “Metal oxide semiconductor structure using oxygen-terminated diamond”, Appl. Phys. Lett. 102 , 242108 (2013) ; http://dx.doi.org/10.1063/1.4811668.
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8:00 PM - EM06.05.23
Investigation of Single Crystal Diamond Deposition Quality and Growth Rate Versus Off-Cut Angle from the (100) Crystallographic Plane
Ayan Bhattacharya 1 , Ramon Diaz 1 , Timothy Grotjohn 1 2
1 , Michigan State University, East Lansing, Michigan, United States, 2 , Fraunhofer USA Center for Coatings and Diamond Technologies, East Lansing, Michigan, United States
Show AbstractDiamond holds some exceptional properties that make it an attractive material for many optical, power electronics and detector applications. Some applications require diamond with low levels of nitrogen impurities so that carrier lifetimes are long. Diamond detectors for high energy particles is one such application. While reducing the nitrogen impurity level improves the performance of the detectors [1], it also makes the diamond more difficult to grow in thick layers of greater than 100 µm thick. This study looks at the quality of the diamond growth and the diamond growth rate versus off-cut angle of the top surface from the (100) crystallographic plane and the design of the holder for the substrate during growth.
In this study diamond substrates of size 3.5 mm x 3.5 mm are prepared with the top growth surface at either 0, 2.5, 5 or 10° from the (100) plane in the crystal. Diamond deposition is performed in a microwave plasma-assisted CVD system [2] using hydrogen and methane feedgas mixtures. Depositions are performed for times of 2, 12 and 24 hours. Diamond layers of 30 µm to 400 μm are grown. The top growth surface is examined to determine the growth morphology including terracing of the surface and appearance of pyramidal features, the evolution of the top growth surface with time, and the growth rate variation versus the position on the top surface as the top surface evolves with time. It is found that the diamond top surface evolves with two different top angles from the (100) plane for non-zero off-cut angles of the starting surface. The quality is investigated with photoluminescence and etch pit studies. A model is developed that looks at the evolution of the top surface as the diamond grows for various angles of off-cut from the (100) plane.
References:
1. A. Bhattacharya, T. A. Grotjohn and A. Stolz, Degradation of single crystal diamond detectors in swift heavy ion beams, Diamond and Related Materials (2016) 70, 124-131.
2. Lu J, Gu Y, Grotjohn TA, Schuelke T, Asmussen J. Experimentally defining the safe and efficient, high pressure microwave plasma assisted CVD operating regime for single crystal diamond synthesis. Diamond and Related Materials (2013) 37, 17–28.
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8:00 PM - EM06.05.24
Detonation Nanodiamond as Artificial Pinning Centre in YBCO Films
Silvia Orlanducci 1 , Andrea Augieri 2 , Valentina Pinto 2 , Fabio Fabbri 2 , Angelo Vannozzi 2 , Fabio Domenici 1
1 Department of Chemical Sciences and Technologies, Tor Vergata University, Rome Italy, 2 , Superconductivity Laboratory, ENEA, Frascati (Rome) Italy
Show AbstractSince the discovery of high-temperature superconductivity in cuprate, efforts have focused on developing a high-current superconductive wire technology to fully exploit their fundamental current-currying capability. Super conductive YBCO based tape have achieved the needed requirements for the power demand and production of 2nd generation superconductive wires. The techniques used in the production of superconductive wires have given new alternatives, like chemical solution deposition, where the main advantage is a lower economic impact in its fabrication to respect the physical deposition techniques that need of sophisticated high vacuum systems. Furthermore, it allows for an easy scalability and thus it is a way to obtain competitive commercial superconductive wires. However, to achieve the maximum potential of applications it is necessary to better understand the phase stability and reactivity of the organometallic solution and to improve the introduction of proper pinning agents inside YBCO film. The chemical techniques employed for the deposition of thin films of YBCO use organometallic solutions, generally acetates and trifluoroacetates, of Y, Ba and Cu that are dissolved in water or organic solvents. Then the solution is deposited on the substrate and subjected to heat treatment until YBCO formation.
The performance of the films can be improved by the introduction of nanometric artificial defects (APC, artificial pinning centre) that increase the ability to “pinning” of the magnetic vortices by the superconductor improving the transport properties in the presence of magnetic field. Several materials in form of nanoparticles, such as metal oxides, have been successfully used as APC both in physical and chemical depositions techniques. The size of the nanoparticles (NP) included in the film have to be in the order of 10 nm to observe a significant improvement of transport properties. Morover attention must be paid to the stability of NP that aggregating together, or by reacting with YBCO metals, can affect the quality of the films.
With the intention of overcoming these issues, the possibility of improving YBCO properties by the use of Nanodiamond (ND) has been investigated. ND and, in general, carbon based nanomaterials (CBN) are certainly among the most promising materials developed in recent years due to their unique mechanical and electronic properties. Among the many proposed applications for CBN, their use in the field of high critical temperature superconductors has not still been fully developed, despite the undoubted advantages in terms of stability and size control. In the presented work, the effect of ND addition to YBCO precursor solution on structural and morphological film properties and pinning efficiency has been estimated and results has been used to understand if ND can be a reliable new “tool” for APCs introduction.
8:00 PM - EM06.05.25
Nanodiamond a New Jewel for the Restoration and Conservation of Cultural Heritage
Silvia Orlanducci 1 , Cristina Cicero 2 , Fulvio Mercuri 2 , Eleonora Bischetti 1 , Marco Fagiolo 1
1 Dipartimento di Scienze e Tecnologie Chimiche, Univ of Rome Tor Vergata, Rome Italy, 2 Ingegneria Industriale, Università di Roma Tor Vergata, Rome Italy
Show AbstractThe conservation science is one of the most complex and exiting topics in the materials science, it requires interdisciplinary expertise ranging from the humanities, to the physics and chemistry. Moreover also in this field the scientific development demonstrated that complex tasks of the conservation of the cultural heritage can be solved very effectively using novel nanomaterials and nanotechnology.
Restoration is a complex process, consisting of different procedures depending on the type of the masterpiece, the fragility and the complexity and inherent uniqueness of the work. The materials and techniques used for its creation and current state of conservation also determine the protocol to be followed for an effective restoration of the piece.
Some nanomaterials have been proposed in form of dispersions of nanoparticles, micellar solutions, microemulsions and gels for cleaning, deacidification and consolidation applications. Compared to traditional methods, these new tools have the benefit of considerably less impact on both the operators and the environment using less chemicals.
In such a context, the class of nanodiamonds represents nowadays one of the more exciting material to be used in the field of cultural heritage.In this work we used ND as consolidating and cleaning agent for restoration of ancient papers and parchments. Different nanocomposites and dispersion based on ND have been tested showing very promising results and making ND a high performance additive in the restorer's lab
8:00 PM - EM06.05.26
First Principles DFT Study of Nano-Structural BNC3 Alloys—Structural, Electronic and Optical Properties
Andrew Chizmeshya 1
1 , Arizona State University, Tempe, Arizona, United States
Show AbstractIn the context of new materials based earth-abundant elements CBxNy analogs of diamond continue to command considerable interest due to their improved thermal and chemical stability, and potential for tuning thermal conductivity, optical response and electron mobility for specific mechanical and optical applications. Here we investigate some fundamental properties of a hypothetical BNC3 nano-alloy comprised entirely of covalently linked near-tetrahedral "B-N-C3" units. We propose a unique structure and composition in analogy with new hybrid III-V/IV alloys which have recently been successfully synthesized, such as "silicon-like" AlPSi3. BNC3 alloy is predicted to adopt a nearly cubic symmetry with a lattice parameter only slightly larger (~1%) than that of diamond, and a bulk modulus slightly larger than that of c-BN (only ~13% smaller than that of diamond). Large-scale supercell calculations show that the introduction of orientational disorder among the "B-N-C3" units preserves the diamond-like structure while increasing the energy by +52 meV/atom. The corresponding alloy, with B, N and C atoms randomly distributed on a diamond-like lattice, is found to be significantly less stable (+233 meV/atom). The direct and indirect band gaps of the ordered BNC3 ground state are predicted to be EgDIR = 6.38 eV and EgIND = 4.72 eV, about 5% and 8% smaller than their diamond counterpart, leading to a moderate increase in the absorption coefficient compared to diamond over the 6-10 eV range, and a ~0.4 eV red shift in the absorption edge. The ground state structure is found to be dynamically stable. Infrared and Raman spectra obtained using density functional perturbation theory reveal a rich vibrational structure which can be interpreted in terms of concerted intra- and inter-tetrahedral B, N and C displacements. Nano-structured BNC3 alloys discussed here are found to be thermodynamically stable in relation to elemental constituents, but metastable relative to disproportionation into cubic BN and carbon (diamond).
8:00 PM - EM06.05.27
Nanostructured Arrays for Sensor Systems Monitoring Air Contaminants
Jin Luo 1 2 , Shan Yan 1 , Shiyao Shan 1 2 , Ning Kang 1 , Zakiya Skeete 1 , Hannah Cronk 1 , Ronghua Xu 1 , Kai Luo 1 , Susan Lu 1 , Chuan-Jian Zhong 1
1 , State University of New York at Binghamton, Binghamton, New York, United States, 2 , FlexSurface, Inc, Vestal, New York, United States
Show AbstractAir pollution (indoor or outdoor) is one of the biggest problems to human health. There is an increasing demand for portable or remote sensors for detecting volatile organic compounds (VOCs) and other toxic gases in complex environment. A key challenge for most existing sensors is the lack of sufficient sensitivity and. In this presentation, we will describe nanostructured chemiresistor arrays for integration into a low-cost portable sensor system with plug-and-play modules and wireless feature. The nanostructured materials function as highly-sensitive sensing interfaces, which upon coupling with pattern recognition software further enhance the selectivity. The arrays are integrated with electronic hardware and wireless communication components. The sensor system was tested with different combinations of VOCs. The results will be discussed, along with their implications to application of the sensor system to complex sensing environment.
8:00 PM - EM06.05.28
Development of a Biosensor for Detection of Zika Virus Using 3D Surface Molecular Imprinting
Vincent Ricotta 1 , Yingjie Yu 1 , Yantian Wang 1 , Miriam Rafailovich 1 , Kalle Levon 3 , Marcia Simon 2
1 Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York, United States, 3 Chemical and Biological Sciences, Polytechnic Institute of NYU, Brooklyn, New York, United States, 2 Oral Biology and Pathology, Stony Brook University, Stony Brook, New York, United States
Show AbstractThe emerging Zika virus epidemic is a public health threat of international concern that is rapidly spreading throughout tropical and subtropical Americas. This Aedes mosquito-borne flavivirus is primarily transmitted through the bite from an infected mosquito. However, transmission is also possible through perinatal transmission, sexual contact, and blood transfusion. The vast majority of people infected will not have any symptoms or will not have symptoms serious enough to seek medical attention. This virus becomes of high concern when a woman that is pregnant, or is planning on getting pregnant, is infected. Infection during pregnancy has been linked to serious birth defects, such as, microcephaly, impaired growth, hearing deficits, and defects of the eye. Although uncommon, there has been a recent link of the virus to Guillain-Barré syndrome, an attack on the peripheral nervous system. As a result, the World Health Organization (WHO) has called for the rapid development of Zika virus diagnostics. Currently, there is no vaccine to prevent Zika and available tests rely on RNA or antibodies. Unfortunately, Zika virus RNA in samples is momentary and testing for Zika virus antibody can result in false positive results due to nonspecific binding of related flavivirus antibodies. In this study, a rapid, yet sensitive, biosensor was developed to detect the Zika virus via surface molecular imprinting (MI). The Zika virus particles are 40 nm in diameter, with an outer envelope, which fits well in the natural rms roughness of the PVD gold surfaces used. The Zika virus was co-adsorbed on PVD gold films with alkanethiols, forming a hydrophilic self-assembled monolayer (SAM). The subsequent removal of the imprinted Zika virus particles created lock-and-key cavities in the SAM matrix specific to the Zika virus structure and conformation. Re-adsorption of the Zika virus particles to the imprinted SAM sensor changes the surface potential, which was measured in real-time potentiometrically and verified using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Potentiometric measurements demonstrated the ability of the biosensor to selectively detect the Zika virus and differentiate between the Dengue virus, which is a related flavivirus. This 3-D model of surface MI biosensor detection can be used to aide in the prevention of the spread of the Zika virus by detecting infection at an early stage. This biosensor system is also less time-consuming and more cost-effective than an RNA or an anti-body detection system.
This work was supported by the NSF, Inspire #1344267.
8:00 PM - EM06.05.29
Paper-Based Combined Optical and Electronic Nose Platform for Robust Detection of Volatile Gases
Yu Chen 1 , Sameer Sonkusale 1
1 , Tufts University, Medford, Massachusetts, United States
Show AbstractIn this work, a paper-based optoelectronic sensor is presented for sensing a number of volatile gases in air environment. The proposed optoelectronic sensor is a combination of optical and chemiresistive sensor arrays. The optical sensors are based on chemoresponsive dyes, including Reichardt’s dye, bromocresol purple, methyl red, Bromothymol blue, brilliant yellow and manganese tetraphynylporphyrin (Mn-TPP). The chemiresistive sensors is consisted of nanomaterials, such as carbon nanotube (CNT), PEDOT:PSS, graphite and Ionic liquid. The optoelectronic sensor is tested under air environment with different volatile gases and its mixtures of varying concentrations, including methanol, ammonia, toluene, acetone and ethanol (totally 7 classes). The detected electrical and optical responses together form a unique signature for each volatile gas and its mixture.
The sensor is exposed to the targeted gas at three different concentrations (50%, 15%, 7.5%). It is observed that the color change of these optical sensor arrays varied with different gases, resulting in different color patterns. The change of R, G, B channel intensities are recorded as quantitative value for comparison, with a variation from 0% to 64% compared with the original R, G, B intensities of each dye. The selected chemiresistors also have varying sensitivity towards different gases. The variation of resistance change can range from 10% to 100% according to different gas analytes. By combining electrical and optical responses, the sensor is able to discriminate a richer set of gases (or mixture), which may not be easily distinguished using electrical or optical sensors alone. This optoelectronic sensor is easily fabricated with a “Paint-on-paper” technique, with flexibility in tuning the size of the sensor and the number of sensing elements. Machine learning method is applied to clearly classify the sensor responses to different analytes and its mixtures.
8:00 PM - EM06.05.30
Smartphone Based Food Quality Monitoring Using Paper-Based Colorimetric Sensor
Yu Chen 1 , Guoqing Fu 1 , Yael Zilberman 1 , Weitong Ruan 1 , Shideh Kabiri 1 , Eric Miller 1 , Sameer Sonkusale 1
1 , Tufts University, Medford, Massachusetts, United States
Show AbstractFood quality monitoring is usually done during the food supply chain by qualified food inspectors using expensive equipment. It is crucial to empower the consumers with low-cost and training free technique to monitor food freshness in daily use to avoid food wastage and prevent food borne illness. In this work, we propose a low-cost solution by employing a colorimetric sensor array to monitor food condition. The sensor is based on cross-reactive vapor sensitive dyes (Nile red, Zn tetraphynylporphyrin, methyl red) encapsulated in resin micro-beads, which are impregnated onto a low cost paper substrate in a barcode pattern. A smart phone camera is used to read color information from the sensor barcode for quantitative estimate of the food quality. As-fabricated sensor was placed on the surface of a piece of fresh chicken meat and then packaged with a plastic wrap. The experiment consisted of placing barcode sensors on different pieces of chicken meat to form sampling groups. For comparison, those samples are divided into three groups kept under different temperature conditions. The 1st group of samples are kept under room temperature (20 °C) and the 2nd group of samples are kept in the refrigerator (5 °C), while the 3rd group of samples are cycled alternately between refrigerator and room temperature at the interval of 24 hours. During 5 days observation, the images of all groups of samples were taken four times a day, with two hours interval in between the reading. The R channel intensities of all the sensing areas on all the sensors under different temperature conditions are extracted to extract sensor’s sensitivity. It is observed that the spoilage status of the chicken samples experienced a significant daily change, which can be used to predict the age. To further explore the sensor's sensitivity within a day, the sensor's responses at two hour interval is recorded and its hourly responses under 20 °C were distinguished using PCA analysis. The sensing results indicate that the sensor could easily distinguish chicken status according to the varying spoilage rate of chicken under different temperatures. In addition, the sensor can monitor chicken freshness at hourly precision under room temperature. The sensor fabrication is low-tech and easy to perform. By using paper and plastic tape as a substrate, barcode sensor also possesses the merits of being low-cost for use with both common and expensive foods. The smartphone-based detection provides a training free and low-cost operation.
8:00 PM - EM06.05.31
PN Junctions in Polycrystalline and Single Crystal Diamond
Gary Harris 1 2 , Amber Wingfield 1 2 , Marko Loncar 3 , Aaron Jackson 1 2
1 , Howard University, Washington, District of Columbia, United States, 2 , HNF, Washington, District of Columbia, United States, 3 Eng, Applied Physics, Harvard University, Cambridge, Maryland, United States
Show AbstractIn this investigation, we will detail the characteristic of diamond p-n junctions fabricated using a hot-filament chemical vapor deposition system (HFCVD), boron-dope p-type layer and a phosphorus-doped n-type layer on (100) single diamond crystal diamond and on diamond grown on 6H silicon carbide. The cross section of the p-n junction was revealed by mesa etching. The boron doped layer was formed by two difference methods: boron oxide (B2O3) doping during growth and growth by using a dilute gas of 0.2% of diborane (B6H2 ) in hydrogen. The n layer was formed by phosphorus diffusion using a solid source. A typical junction thickness was over one micron with an intrinsic (undoped) layer sandwiched between the p bottom layer and the n top layer. The doping on the layers varied from 1020 cm-3 to 1018 cm-3. These junctions had a forward turn-on voltage over 2.0 volts. The deep UV results of these devices will also be discussed. This work was supported by the STC Center for Integrated Quantum Materials, NSF Grant No. DMR-1231319. This work was performed in part at the Harvard University Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by the National Science Foundation under NSF award no. 1541959.
8:00 PM - EM06.05.32
Rapid Detection of Toxic Heavy Metals with Boron-Doped Diamond Sensors
Michael Becker 1 , Cory Rusinek 1 , Robert Rechenberg 1 , Mary Ensch 1 2 , Bettina Wehring 1 , Thomas Schuelke 1 2 , Aaron Hardy 1
1 , Fraunhofer USA Center for Coatings and Diamond Technologies, East Lansing, Michigan, United States, 2 , Michigan State University, East Lansing, Michigan, United States
Show AbstractToxic heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg) cause serious health complications and ingestion of these toxins through contaminated drinking water, even at trace levels, has become a prominent issue. Chronic exposure to toxic metals such as Pb, Cd, and Hg is carcinogenic while causing other problems like kidney failure, severe neurotoxicity, and IQ loss. These problems are only magnified in children as several stages of bodily development can be severely hindered. Electroanalytical methods are an attractive technique for trace detection of heavy metals due to low cost of experimental tools, low limits of detection, multi-element analysis capability, and the possibility to package them into sensing devices. Specifically, boron-doped diamond (BDD) is a rugged, yet sensitive electrode material with significant potential in electrochemical sensing. Using square-wave stripping voltammetry (SWSV), we have developed BDD micro-electrode arrays (MEAs) as well as macro-electrode disks, achieving detection limits as low as 200 parts-per-trillion (ppt) for Pb with a deposition time of just 2 minutes. This is nearly 100x below the 15 ppb maximum contaminant level (MCL) in drinking water set by the Environmental Protection Agency (EPA). MEAs of various diameter and spacing were investigated to find the optimum geometry for both single and multi-element detection of Pb, Cd, Hg, Cu and Mn where results were compared with those obtained at various macro-electrode sizes. Additionally, pen-like sensors incorporating the optimized BDD working
electrode, a BDD reference electrode, and BDD counter electrode were constructed and used for the detection of the aforementioned metal ions. Long-term stability of the BDD quasi-reference electrode was investigated in detail. The applicability of all electrode constructions for the detection of metal ions in drinking and environmental water samples were studied for rapid detection at home or in the field.
8:00 PM - EM06.05.33
Properties of Zirconium and Niobium Ohmic Contacts on Boron-Doped Diamond
V. Mortet 1 2 , Andrew Taylor 1 , M. Davydova 1 , Pavel Hubik 1 , J. Moore-Chevalier 1 , D. Trémouilles 3 , A. Soltani 4
1 , Institute of Physics of CAS, v.v.i., Prague Czechia, 2 Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno Czechia, 3 LAAS-CNRS, Université de Toulouse, Toulouse France, 4 , Université de Sherbrooke, LN2, Sherbrooke, Quebec, Canada
Show AbstractOhmic contacts with low specific contact resistance are essential for the fabrication of electronic devices. Numerous carbide forming metals have been studied for the fabrication of ohmic contacts on diamond. Yet, zirconium and niobium as carbide forming metals have not been extensively studied. In this work, we have measured and compared properties of zirconium and niobium contacts with titanium and tantalum contacts on p-type epitaxial diamond layers with various boron concentrations and annealed at different temperatures from 400 to 700 °C. Specific contact resistance has been measured by conventional and circular transmission line measurement (TLM) methods at temperatures between RT and 200 °C to assess the transport mechanisms at the metal/semiconductor interface. The use of both zirconium and niobium has successfully led to ohmic contacts with low specific contact resistance and barrier height. We have observed improved thermal stability of zirconium and niobium contacts compared to titanium contacts.
Acknowledgements: This work was financially supported by the project 17-05259S of Czech Science Foundation, the French-Czech Project Barrande 35785SC - 7AMB16FR004 of the Czech Ministry of Education, Youth and Sports and the J.E. Purkyne fellowship awarded to V. Mortet by the Czech Academy of Sciences.
Symposium Organizers
Philippe Bergonzo, CEA Saclay
Timothy Grotjohn, Michigan State University
Mutsuko Hatano, Tokyo Institute of Technology
Christoph Nebel, Fraunhofer IAF
Symposium Support
Applied Diamond, Inc.
Arios Ltd.
CARAT Systems
CIVIDEC Instrumentation GmbH
Cline Innovations, LLC
DiamFab
ICDAT LTD.
Microwave Enterprises, Ltd.
Fraunhofer Center for Coatings and Diamond Technologies- Michigan State University
New Diamond Technology, LLC
Seki Diamond Systems
EM06.06: Nanodiamond
Session Chairs
Tuesday AM, November 28, 2017
Hynes, Level 1, Room 108
8:30 AM - EM06.06.01
HOMO-LUMO Separation via Non-Covalent Binding of Polypyrrole with Peroxide Terminated Diamond Nanoparticles
Petra Matunova 1 2 , Vit Jirasek 2 , Bohuslav Rezek 1 2
1 , Czech Technical University, Prague Czechia, 2 , Institute of Physics CAS, Prague Czechia
Show AbstractInexpensive, unobtrusive, and safe renewable energy sources are nowadays increasing in importance. Diamond-based inorganic-organic hybrid systems may have an immense, yet still mostly unexplored potential in such photovoltaic solar cells [Nanoscale Res. Lett. 6 (2011) 238; Phys. Stat. Sol. (a) 213 (2016)]. In this work, we focus on studying interactions of PPy with diamond nanoparticles (so-called nanodiamonds - NDs) by density functional theory (DFT) to reveal and better understand effects possibly brought about by the nanoscale features.
The DFT method implemented in Gaussian 09 software was used for the geometry optimization of all the structures employing B3LYP functional with the 6-31G(d) basis set. We used (111) and (100) ND surface slabs consisting of 3 C layers of 6 × 6 pattern and surface terminating layer of O atoms. The slabs represented a corner of nanodiamond particle. We compare PPy in chemisorbed and physisorbed configurations on one of the most probable (111) ND surface having the most common hydrogen-terminated and peroxide-terminated surfaces. The highest charge transfer is obtained for PPy physisorbed on peroxide-terminated 1 × 1 (111) ND surface slab (Δq = 0.24 e-). Moreover, in a significant number of cases, we obtain a spatial separation of HOMO and LUMO at the interface, which seems promising for photovoltaic applications. In spite of non-covalent binding, peroxides may be more efficient in comparison with hydrogens for PPy adsorption and photovoltaic applications of the hybrid nanodiamond system.
Computational resources were provided by the CESNET LM2015042 and the CERIT Scientific Cloud LM2015085. Financial support from Czech Science Foundation (15-01809S), Student grant agency of the Czech technical university, and European Regional Development Fund project CZ.02.1.01/0.0/0.0/15_003/0000464 is gratefully acknowledged.
8:45 AM - EM06.06.02
Hydrogenated 2 nm Detonation Nanodiamonds—Technology and Applications
Stepan Stehlik 1 , Marian Varga 1 , Pavla Stenclova 1 , Lukas Ondic 1 , Martin Ledinsky 1 , Jiri Pangrac 1 , Ondrej Vanek 2 , Jan Lipov 3 , Daria Miliaieva 1 4 , Alexander Kromka 1 , Bohuslav Rezek 4 1
1 , Institute of Physics, AS CR, Prague Czechia, 2 Department of Biochemistry, Charles University, Prague Czechia, 3 Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague Czechia, 4 Faculty of Electrical Engineering, Czech Technical University in Prague, Prague Czechia
Show AbstractDetonation nanodiamonds (DNDs) with typical size of 4-5 nm and narrow size distribution are routinely prepared from oxygen-deficient explosives on industrial scale. As for all nanomaterials, control of their size down to molecular level is of major importance with respect to their potential applications ranging from biomedicine to photovoltaics. Due to a limited control of the detonation synthesis, DNDs with mean size of 2 nm or lower have not been available so far in a reasonable amount, although nanodiamond can, in general, stably exist down to 1 nm (S. Stehlik et al., J. Phys. Chem. C. 119 (2015) 27708–27720). Recently, a high-yield technique, which provides DNDs with the mean size around 2 nm (volumetric distribution) by means of controllable size reduction of conventional 4-5 nm DNDs via oxidative etching in air, was reported (S. Stehlik et al., Sci. Rep. 2016, 6, 38419) and opened new perspectives in numerous scientific domains.
In this work we demonstrate feasibility of obtaining high-quality hydrogenated 2 nm detonation nanodiamonds with narrow size distribution. Analytical ultracentrifuge served here as in particular useful and accurate tool for analyses and adjustment of size distribution of DNDs in colloidal dispersions on nanometer scale. We show that hydrogenation of oxidized 2 nm DND via annealing at 600°C in hydrogen gas changes only the DND surface chemistry without affecting the 2 nm diamond crystalline core as documented by FTIR and Raman spectroscopy. This evidences the stability of hydrogenated DNDs in this size range. Due to large variability of DND surface chemistry (e.g. hydrogenated to oxidized) and corresponding zeta potentials (positive to negative) which is here shown to work down to 2 nm or below, electrostatic interaction with substrates and other objects can be optimized.
For instance, we show how to apply these novel 2 nm H-DNDs to form homogeneous, ultra-thin (2 nm), extremely dense (1.3 × 1013 cm-2) and smooth (RMS < 1 nm) nucleation layers for growing ultra-thin (8 nm) continuous NCD films with distinct photoluminescence from SiV centers. We also discuss their potential for use in dye sensitized solar cells or for penetration through biological membranes.
9:00 AM - EM06.06.03
Hydroxyl Radical and Hydrated Electron Production from Surface-Modified Detonation Nanodiamonds
Magdalena Kurzyp 1 , Emilie Brun 2 , Cecile Sicard-Roselli 3 , Emilie Nehlig 4 , Hugues Girard 1 , Samuel Saada 1 , Jean-Charles Arnault 1
1 Diamond Sensors Laboratory, CEA, LIST, Gif sur Yvette France, 2 Laboratory of Physical Chemistry, University Paris-Sud, CNRS UMR 8000, Orsay France, 3 Laboratory of Physical Chemistry, University Paris-Sud, CNRS UMR 8000, Orsay France, 4 Tritium Labelling Laboratory, CEA, Joliot, Gif-sur-Yvette France
Show AbstractDetonation nanodiamonds (DNDs) have attracted researchers’ attention due to possible bio-applications, e.g. in cancer treatment as drug-delivery carriers, imaging agents or even radiosensitizing nanoparticles [1,2]. Commercially-controlled production by detonation technique delivers nanoparticles of 4-10 nm made of chemically inert diamond-core and non-diamond surface terminations. However, electronic properties and colloidal stability of as received nanoparticles require further chemical or physical surface modifications.
Recently reported the radiosensitizing effect of the microwave-plasma hydrogenated DNDs [3] has shown an increase of + 40% in hydroxyl radical (HO•) production under X-ray irradiation (E = 17.5 keV). Such an effect could be associated with the negative electron affinity (NEA) of the hydrogen-terminated surface. In addition to that, this phenomenon is concentration and dose-dependent along with the initial source of DND particles not playing a role. The same phenomenon was not observed for carboxylated DNDs used in the experiment as a negative control where electron emission is not expected due to the positive electron affinity (PEA).
In the current study, the comparison of HO• production efficiency between thermally annealed and plasma hydrogenated DNDs is presented. Utilization of the higher energy range (gamma rays, E = 1.25 MeV) shows that plasma hydrogenated nanoparticles are equally responsive to an external stimulation. More interestingly, other surface modifications, such as early-stage graphitization [4], appears to be as active as hydrogenated nanoparticles under irradiation. The latter findings suggest that the mechanism involved in the electron emission from the electrically-active nanodiamond surface can be related to direct interaction with water molecules [5].
[1] Vaijayanthimala, V. et al., Nanodiamond-mediated drug delivery and imaging: challenges and opportunities, Expert Opin Drug Deliv. 2015
[2] Grall, R. et al., A combination of hydrogenated nanodiamonds and g-irradiation drive radiation-resistant cancer cells to senescence, Biomaterials 2015
[3] Kurzyp, M. et al., Hydroxyl Radicals Production Induced by Plasma Hydrogenated Nanodiamonds under X-ray Irradiation, ChemComm 2017
[4] Petit, T. et al., Early stages of surface graphitization on nanodiamond probed by x-ray photoelectron spectroscopy, Physical Review B 2011
[5] Petit, T. et al., Unusual Water Hydrogen Bond Network around Hydrogenated Nanodiamonds, The Journal of Physical Chemistry 2017
9:15 AM - EM06.06.04
Positive Zeta Potential of Nanodiamonds
Laia Gines 1 , Soumen Mandal 1 , Ashek Ahmed 2 , Chia-Liang Cheng 2 , Oliver Williams 1
1 School of Physics and Astronomy, Cardiff University, Cardiff United Kingdom, 2 Department of Physics, National Dong Hwa University, Hualein Taiwan
Show AbstractIt is well known that diamond nanoparticles' surface charges play a determining role in view of its subsequent material characteristics. Surface charges are determined by the surface functional groups present in the diamond nanoparticles, and can be controlled through different cleaning methods, annealing treatments or surface functionalization. The manipulation of these surface charges will be deeply important for a wide range of applications and will have an important influence over colour centres fluorescence.
However, for most applications, diamond nanoparticles have to exhibit stability in colloidal systems to prevent particles’ aggregation. The key indicator of a colloid stability is known as zeta potential and is defined as absolute zeta potential values greater than 30mV. Diamond nanoparticles usually exhibit negative zeta potentials due to oxygen based surface functional groups, but hydrogenated diamond nanoparticles were proved to have a positive zeta potential although the origin was uncertain.
In this work, the positive zeta potential of commercial 50 nm size diamond nanoparticles after vacuum annealing treatments at 1000°C is explained. At this temperature, a graphitic layer is created around the diamond core of the diamond nanoparticles. Positive zeta potential in nano- structured carbons is explained due to the presence of basal planes in graphite, which leaves oxygen-free Lewis sites and so promotes the suppression of acidic functional groups. At the same time, sp2 carbon creation on diamond nanoparticles surface eases low temperature (500°C) diamond nanoparticles hydrogenation, previously demonstrated for detonation diamond (5nm).
EM06.07/EM08.04: Joint Session: NV Ensembles and Architectures
Session Chairs
Mutsuko Hatano
Shashank Misra
Tuesday PM, November 28, 2017
Hynes, Level 3, Room 300
10:00 AM - *EM06.07.01/EM08.04.01
Creating Quantum Materials with Spins in Semiconductors
Brian Zhou 1 , David Awschalom 1
1 , University of Chicago, Chicago, Illinois, United States
Show AbstractThere is a growing interest in exploiting the quantum properties of electronic and nuclear spins for the manipulation and storage of information in the solid state. Although conventional electronics avoid disorder, recent efforts embrace materials with incorporated defects whose special electronic and nuclear spin states allow the processing of information in a fundamentally different manner because of their explicitly quantum nature [1]. These defects possess desirable qualities – their spin states can be controlled at and above room temperature, they can reside in a material host amenable to microfabrication, and they can have an optical interface near the telecom bands. Here we focus on recent developments that exploit precise quantum control techniques to explore coherent spin dynamics and interactions. In particular, we manipulate and measure the geometric (Berry) phase of a single spin in diamond using all-optical control techniques [2], and investigate the robustness of this control pathway to noise as well as its viability for implementations of photonic networks of quantum states. Separately, we find that defect-based electronic states in silicon carbide can be isolated and read with high fidelity at the single spin level with long spin coherence times [3], can achieve near-unity nuclear polarization [4] and be robustly entangled at room temperature [5]. Finally, we identify and characterize a new class of optically controllable defect spin based on chromium impurities in both silicon carbide and gallium nitride [6].
[1] D.D. Awschalom, L.C. Bassett, A.S. Dzurak, E.L. Hu and J.R. Petta, Science 339, 1174 (2013).
[2] B. B. Zhou et al., Nature Phys. 13, 330 (2017); B. B. Zhou et al., arXiv:1705.00654.
[3] D. J. Christle et al., Phys. Rev. X7, 021046 (2017).
[4] A. L. Falk, P. V. Klimov, et al., Physical Review Letters 114, 247603 (2015).
[5] P. V. Klimov, A. L. Falk, D. J. Christle, V. V. Dobrovitski, and D. D. Awschalom, Science Advances 1, e1501015 (2015).
[6] W. F. Koehl et al., Editors Suggestion, Phys. Rev. B 95, 035207 (2017).
10:30 AM - *EM06.07.02/EM08.04.02
Coherent Optical Control of Silicon-Vacancy Center Spins in Diamond
Christoph Becher 1
1 , Saarland University, Saarbruecken Germany
Show AbstractColor centers in diamond, i.e. atomic-scale, optically active defects in the diamond lattice, have received large recent attention as versatile tools for solid-state-based quantum technologies ranging from quantum information processing to quantum-enhanced sensing and metrology. They provide individually addressable spins with very long coherence times, narrow optical spectra and bright single-photon emission. However, identifying a spin impurity which combines all of these favorable properties still remains a challenge.
In this context, the negatively charged SiV center in diamond features an advantageous electronic structure and superior spectral properties [1]: At liquid helium temperatures, the SiV exhibits a narrow zero phonon line (ZPL) with a four-line fine structure and lifetime-limited linewidths on the order of 120MHz [2]. Furthermore, due to its small Huang-Rhys factor, up to 80% of the fluorescence is emitted via the ZPL. Moreover, the SiV offers an optically accessible Λ-type level structure with a large orbital level splitting and previous studies determined the ground state coherence time of the center to be on the order of 40ns [3].
The specific level structure of the SiV and the spin-dependent fluorescence enable all-optical coherent control of its internal states; the large ground state splitting furthermore allows for using broadband, ultrafast laser pulses for coherent manipulation. We here report on all-optical coherent control of the orbital degree of freedom based on Raman transitions [4]. These experiments can be extended to the spin degree of freedom for SiV centers in strong magnetic fields [5].
A limitation of current experiments is the short ground state coherence time which is due to phonon-induced transitions between the orbital states. In order to extend the coherence time we follow two routes: 1. We report on coherent control experiments at very low temperatures (mK) where phonons are frozen out. Despite a large increase in spin relaxation time (T1) we find that the spin coherence time (T2*) is still short which is attributed to coupling to a local spin bath. 2. We investigate phonon engineering as a tool to reduce the phonon density of states (PDOS) at the frequency of the ground state splitting (50GHz). In particular, we find that diamond nanowire structures with diameter < 200nm exhibit phonon confinement effects, leading to a reduced PDOS at 50GHz. At the same time the nanowire structures provide high photon collection efficiencies enabling efficient spin-photon interfacing. The combination of low-temperature operation and efficient optical interfacing are promising techniques for scaling up the coupling of SiVs in a quantum network.
References
[1] C. Hepp et al., Phys. Rev. Lett. 112, 036405 (2014).
[2] L. J. Rogers et al., Nat. Commun. 5, 4739 (2014).
[3] B. Pingault et al., Phys. Rev. Lett. 113, 263601 (2014).
[4] J. N. Becker et al., Nat. Commun. 7, 13512 (2016).
[5] B. Pingault et al., Nat. Commun. 8, 15579 (2017).
11:00 AM - EM06.07.03/EM08.04.03
GaN Nanowires as Electrically Active Waveguides for Nitrogen Vacancy Center Read-Out and Charge State Control
Martin Hetzl 1 , Jakob Wierzbowski 1 , Theresa Hoffmann 1 , Verena Zuerbig 2 , Christoph Nebel 2 , Martin Stutzmann 1
1 Walter Schottky Institute, TU Munich, Garching Germany, 2 , Fraunhofer Institute for Applied Solid State Physics IAF, Freiburg Germany
Show AbstractNitrogen vacancy centers (NVs) in diamond are promising candidates for quantum computing applications. However, due to charge state instabilities of surface-near NVs, their optical and spin coherence times are fluctuating. In addition, the large refractive index of diamond is not beneficial for the optical read-out of NVs.
We demonstrate the deterministic epitaxial growth of GaN nanowires (NWs) on diamond (111) surfaces in an n/p-heterodiode structure acting as efficient nano-waveguide for optical read-out and, at the same time, as electrical nano-contacts to control the charge state of single or ensembles of NVs close to the diamond surface. The NWs are fabricated via plasma-assisted molecular beam epitaxy in the selective area growth mode, which allows the implementation of NW arrays with predefined NW diameters, lengths and periods. By employing finite difference time domain (FDTD) simulations, we optimize these parameters to efficiently guide the excitation laser light into the diamond substrate and extract the NV photoluminescence through the GaN nanowires, respectively. This alllows an enhancement of the PL signal of the NVs by over one order of magnitude at room temperature and also at 10 K.
In order to prevent blinking of the NVs during laser excitation, the charge state of surface-near NVs is stabilized and adjusted by applying a voltage to the n-GaN NW/p-diamond nano-diodes.
11:15 AM - *EM06.07.04/EM08.04.04
Photophysics of Electronic Transitions on NV Centre in Diamond—Towards Scalable Quantum Chip Architecture
Milos Nesladek 1 , Michal Gulka 1 2 , Emilie Bourgeois 1
1 , imec, Division IMOMEC and Hasselt University, Diepenbeek Belgium, 2 Biomedical Engineering, Czech Technical University, Kladno Czechia
Show AbstractScalable principles for quantum state readout are one of the key- open questions in quantum technology. Building on the recent results of photoelectric detection of magnetic resonances (PDMR) [1,2] we review the prospects of PDMR technique for solid-state qubit devices in diamond. One of the advantages of PDMR over optically detected magnetic resonances (ODMR) are high detection rates ~ 5 x 109 s-1, significantly exceeding standard ODMR. Consequently, PDMR might enable single shot readout of individual NV centres and provide a fast data acquisition essential for quantum sensing as well as quantum computation devices. To achieve this goal the photoelectric gain associated with 2-photon ionization scheme is to be optimised. In this work we discuss photophysics of the transitions on NV centre and address several quantum readout scenarios for obtaining highest signal/noise ratio. We discuss the trapping and recombination kinetics and emphasize the role of point defects in the diamond lattice on the influence of the magnetic resonance contrast. In specific configuration the normally observed negative PDMR contrast can be reverted to positive. We demonstrate pulsed PDMR measurements, compatible with coherent spin manipulation realized on quantum chips and discuss prospects of the chip design.
[1] E. Bourgeois et al Nat. Comm. 6, 8577 (2015).
[2] M. Gulka et al, Phys. Rev. Applied 7, 044032, (2017)
11:45 AM - EM06.07.05/EM08.04.05
Realization of Nano-Tesla Sensitivity in Wide Field Dynamical Decoupling by Delta-Doped NV Centers
Kosuke Mizuno 1 , Hitoshi Ishiwata 1 , Makoto Nakajima 1 , Takayuki Iwasaki 1 , Mutsuko Hatano 1
1 , Tokyo Institute of Technology, Meguro Japan
Show AbstractNanoscale magnetic resonance imaging (MRI) could be realized using nitrogen-vacancy (NV) center in diamond with optical spatial resolution and high magnetic sensitivity. This technique could be used to explorer cell membrane structures that were impossible to investigate using conventional MRI technique due to its limited spatial resolution. Capability of nanoscale MRI could be further extended by using our perfectly aligned high density delta-doped NV centers [1] for improved signal-to-noise ratio and high contrast that could be obtained uniformly over wide area. We constructed a wide-field magnetometer with 20 micrometer square observation area by initializing NV centers through epi-illumination and detecting the fluorescence by charge coupled device (CCD) camera. In this study, we propose realization of nano-tesla sensitivity in wide field by using an image intensified CCD (ICCD) camera and a high power laser excitation.
Inhomogeneity is inevitable with the wide field technique, which arise from spatial distribution of laser power, microwave intensity, density and coherence property of NV center. Inhomogeneity leads to reduced operation fidelity and change in measured values. We investigated the effect of laser and microwave intensity on XY8 dynamical decoupling measurement using delta-doped NV centers. Normalizing the fluorescence intensity eliminates the effect of laser power inhomogeneity. Conversely, microwave power determines operation fidelity directly and requires more careful designing.
Secondly, previous study of wide-field NV center technique [2] is using CCD camera with a lower signal-to-noise ratio and a lower shutter speed than photo diodes. It requires many repetitive measurements during single exposure. CCD camera operate with readout time of a few milliseconds which is approximately 10 times longer than the interaction time of NV center limiting its sensitivity in wide field imaging. In contrast, ICCD camera with nanosecond time resolution allows higher signal-to-noise ratio by extracting data within first 300 ns of fluorescence and reduce back of laser excitation compared to CCD camera. Combining 5 W high power laser and delta-doped CVD diamond [1], numerical estimate of the sensitivity reaches 80 nT/Hz1/2. Since fluctuating magnetic field from the nuclear spins 9 nm above surface is approximately 350 nT-rms [3]. Numerical estimate provides possibility of nuclear spin detection by using wide-field technique. Nanoscale MRI technique shows possibility to investigate cell membrane structures and eventually clarify interaction between proteins at cell membrane.
Acknowledgements:
This work was supported by CREST, JST and JSPS KAKENHI Grant (No. JP17H01262)
[1] Ishiwata et al., arXiv:1704.03642 (2017).
[2] DeVience et al., Nat. Nanotechnol. 10, 129 (2015).
[3] Pham et al., Phys. Rev. B 93, 45425 (2016).
EM06.08: Diamond for Biosensing and Interfacing
Session Chairs
Tuesday PM, November 28, 2017
Hynes, Level 1, Room 108
1:45 PM - *EM06.08.01
Diamond Electrodes for Fast Scan Cyclic Voltammetry in Biologic Systems
Kevin Bennet 1 , Seth Hara 1 , Jonathan Tomshine 1 , Felicia Manciu 2
1 , Mayo Clinic, Rochester, Minnesota, United States, 2 Physics, University of Texas at El Paso, El Paso, Texas, United States
Show AbstractDevelopment of durable, synthetic boron-doped diamond-based electrodes capable of measuring neurochemical release in humans through fast-scan cyclic voltammetry (FSCV) is providing options for the development of long term implantable systems. Comparison with carbon fiber electrodes for chronic neurochemical recording shows significantly reduced electrode degradation over time.
Methods: Boron-doped diamond microelectrodes were created and their performance evaluated for measurement of real-time detection of neurochemical release using Wireless Instantaneous Neurochemical Concentration Sensing (WINCS)-based FSCV.
Compared to conventional carbon fiber electrodes, the boron doped diamond-based electrodes exhibited more than two orders-of-magnitude improvement in their compressive strength limit and demonstrated electrochemical longevity in vitro without deterioration. Techniques of signal processing were applied to improve the apparent sensitivity of the diamond electrodes.
The exceptional mechanical properties of diamond overcame many mechanical issues, while the electrochemical characteristics after signal processing provided sufficient sensitivity to measure basal neurochemical levels in tissue. The physical properties of diamond-based electrodes largely overcome mechanical issues of insertion, while their electrochemical characteristics offer significant potential for chronic recordings in vivo. In the future, the combination of physical, biological and electronic properties may enable sensor systems for human applications such as a FSCV-based closed-loop DBS system for practical implementation.
2:15 PM - EM06.08.02
Oxygenated Nanodiamonds for Human Neural Stem Cell Adhesion, Proliferation and Differentiation
Alice Taylor 1 , Richard Jackman 1
1 LCN, University College London, London United Kingdom
Show AbstractNeural stem cells (NSCs) have great potential for inducing repair in damaged areas of the nervous system. NSCs have the ability to self-renew, but also are able to differentiate into neurons, oligodendrocytes and astrocytes, which are the main cells in the central nervous system (CNS). Understanding the differentiation into these cell lineages is critical for regenerative therapy treatment of diseases such as Parkinson’s and Alzheimer’s, as detailed knowledge of how these specific cells are affected by disease is vital [1]. In order to utilise the potential of stem cells in the field of regenerative medicine, it is essential that we are able to isolate the cells from their natural setting, propagate the cells in culture, and introduce the cells to a foreign environment [2]. Given the outstanding biocompatibility of nanodiamonds (NDs) towards neuronal cells [3], nanocrystalline diamond (NCD) towards hNSCs [4] and their excellent ability to promote neuronal cell adhesion and outgrowth, the
proliferation and differentiation of human NSCs (hNSCs) and their relationship with functionalised ND coatings has been investigated.
Firstly, the interaction of hNSCs with varying surface functionalised NDs is investigated; with Oxygen-terminated functionalised surfaces favouring the proliferation and adhesion of hNSC, compared to those with a Hydrogen-terminated surface. Quantitative cell count data of the hNSCs has been determined on the varying functionalised NDs as well as glass and tissue culture polystyrene (TCPS), along with contact angle and protein adsorption investigations suggesting why O-NDs are highly suited for hNSC growth. Secondly ND surfaces of different functionalisation (H/O) are shown to influence the differentiation and proliferation of hNSCs in varying ways. hNSCs fate has been investigated via inducing and spontaneously differentiating the cells on varying nanodiamond substrates. Neurite tracing analysis was performed on the differentiated cells and ANOVA analysis was done, showing statistically significant differences in neurite extension on H-NDs, O-NDs and the control.
[1] Lindvall O, Kokaia Z. Stem cells for the treatment of neurological disorders. Nature. Nature Publishing Group; 2006 Jun 29;441(7097):1094?6.
[2] Scadden DT. The stem-cell niche as an entity of action. Nature. 2006 Jun 29;441(7097):1075?9.
[3] Thalhammer A, Edgington RJ, Cingolani LA, Schoepfer R, Jackman RB. The use of nanodiamond monolayer coatings to promote the formation of functional neuronal networks. Biomaterials. 2010 Mar;31(8):2097?104.
[4] Taylor AC, Vagaska B, Edgington R, Hebert C, Ferretti P, Bergonzo P, et al. Biocompatibility of nanostructured boron doped diamond for the attachment and proliferation of human neural stem cells. J Neural Eng. IOP Publishing; 2015 Dec 1;12(6):066016.
2:30 PM - EM06.08.03
Cell Migration and Filopodial Dynamics Mediated by Surface Properties of Nanocrystalline Diamond Film
Lei Yang 1 2 , Yuan Lin 4 , Brian Sheldon 2 , Thomas Webster 3
1 , Soochow University, Suzhou China, 2 School of Engineering, Brown University, Providence, Rhode Island, United States, 4 Mechanical Engineering, The University of Hong Kong, Hong Kong Hong Kong, 3 Chemical Engineering, Northeastern University, Boston, Massachusetts, United States
Show AbstractNanostructured surfaces including nanodiamond surfaces have demonstrated extraordinary capacity to influence the functions and responses of cells, yet the mechanisms behind such capacity are still not clear to date. The attempts to understand these mechanisms becomes increasingly important due to the expansive applications of nanodiamond as novel bio-interfaces in drug delivery, neural engineering, biosensing and stem cell therapy. The objective of this study is to investigate, by both experimental and theoretical modeling approaches, the role of nanodiamond surface properties in modulating cell migration and subtle filopodial responses. Firstly, controlling surface properties of nanocrystalline diamond (NCD) film was achieved by altering surface topography and chemical terminations during the microwave-enhanced plasma chemical vapor deposition (MPCVD) process. NCD films with continuously varied grain sizes from nanoscale (<80 nm) to microscale (>600 nm) grains and different surface terminations (affecting surface energy) were prepared. Next, migration of single cell and cell aggregates (each containing 30~50 cells) on various NCD films and subsequent cell morphology were studied. The migration behavior of cells was correlated with the surface topography and energetic state of diamond films, and the extending speed of cell filopodia revealed a dependence on NCD surface topography. In the last part, a theoretical model based on the actin dynamics of filopodial and cytoskeleton was developed to explain the experimental observation, attempting to uncover the mechanisms of the altered cellular responses to diamond surface properties. The modeling predication was in close agreement with the experimental results and therefore this model becomes an effective tool to probe the surface property-mediated cell responses on nanodiamond surface.
2:45 PM - EM06.08.04
CVD Diamond Electrodes for Neural Interfacing
Clément Hébert 1 , Emmanuel Scorsone 2 , Philippe Bergonzo 2
1 Advanced Electronic Materials and Devices Group, Catalan Institute of Nanoscience and Nanotechnology - ICN2, Bellaterra (Barcelona) Spain, 2 , CEA, LIST, Diamond Sensors Laboratory, Gif-sur-Yvette France
Show AbstractBoron Doped Nanocrystalline Diamond (B-NCD) is known as a remarkable material for the fabrication of neural interfaces, taking advantage in particular of its good biocompatibility, electrochemical properties, and stability. Over the last years, in collaboration with electrophysiologists and biologists, such material was structured in various ways to design diamond devices, including Micro-Electrode Arrays (MEAs) that are commonly used in electrophysiology, enabling to probe the neuronal activity distributed over large populations of either neurons or embryonic organs. Specific MEAs were built such as neural prostheses. Other devices specifically developed to exhibit material flexibility (for surgery issues) were developed for neural implants in order to compensate function losses due to lesions or degeneration of part of neural tissues like the Central Nervous System (CNS), cochlea or retina. We developed novel forms of diamond layers fabricated using highly porous and conductive carbon based templates to obtain highly porous diamond electrodes exhibiting high charge transfer performances. The capacitance values typically reached 3mF/cm2 and low electrochemical interfacial impedances compared to non-structured diamond.
Such 3D porous electrodes were integrated in rigid Microelectrode Arrays (MEAs) as well as retina implants to assess their efficiency for the stimulation and recording of the neural system. Today, our 20µm BDD/CNT electrodes exhibit a low mean thermal noise around 5µV and a large charge storage capacity of 10mC.cm-2.
The work was partially financially supported by the Neurocare Project (FP7-NMP- 280433).
EM06.09: Power Devices and Schottky Diodes
Session Chairs
Tuesday PM, November 28, 2017
Hynes, Level 1, Room 108
3:30 PM - *EM06.09.01
Potential of Diamond Power Device and Recent Progress
Satoshi Yamasaki 1 2 , Toshiharu Makino 1 , Daisuke Takeuchi 1 , Hiromitsu Kato 1 , Masahiko Ogura 1 , Yukako Kato 1
1 , National Institute of Advanced Industrial Science and Technology, Tsukuba Japan, 2 , Tsukuba University, Tsukuba Japan
Show AbstractDiamond semiconductor has a high potential for power electronics applications due to high breakdown voltage, high thermal conductivity, and high electron and hole mobility. To be a real power device material we need improve the device fabrication technique, and solve the substrate issues. In addition, we are facing the scientific issues, such as knowing a real physical constant of breakdown voltage, mobility as a function of doping, transport properties affected by excitons, diamond growth related device performance, reliability issues related several kinds of defects, so on.
In this talk we would like to show the recent progress and discuss these issues and the strategy for realization of diamond power devices.
4:00 PM - EM06.09.02
Diamond Schottky Diodes Interactions in Power Electronics Application
Gaetan Perez 1 , Juliette Letellier 2 , Aurélien Maréchal 1 , Pierre-Olivier Jeannin 1 , Pierre Lefranc 1 , David Eon 2 , Nicolas Rouger 3
1 , Université Grenoble Alpes, CNRS – G2Elab, Grenoble France, 2 , Université Grenoble Alpes, CNRS, Institut Néel, Grenoble France, 3 , Université de Toulouse ; LAPLACE ; CNRS ; INPT ; UPS, Toulouse France
Show AbstractSince several years, the power electronics community shows a growing interest for wide band gap semiconductors to design power converters with higher performances. Considering the wide band gap materials physical properties (Silicon Carbide, Gallium Nitride and diamond), diamond seems to be the best candidate for power electronics applications, especially at high temperatures. Recent progresses have been done on diamond power devices leading to devices with promising electrical performances [1], [2]. Regarding to the actual electrical performances of all diamond semiconductors, Schottky diodes are the closest diamond device for integration in industrial power converters, this study is focused on diamond Schottky diodes integration.
Today, most of diamond Schottky devices are composed of several small area Schottky contacts (separated cathodes) with a common ohmic contact (common anode) [3]. However, to design usual power converter based on diamond devices, diamond Schottky diodes have to be associated at the device level to increase the effective device current. In this work, it is shown that due to the device structure, a common impedance is shared between the diodes. A diode current is spread in the p+ layer between the Schottky contact and the Ohmic contact, then two diodes share a current path involving the common impedance. A special care is then needed in the way to separately use some diodes of such a diamond device depending to the required application.
To highlight this phenomenon, a 3D device model is done to quantify this current spreading and impedance sharing. Moreover, different issues of this phenomenon for device integration are presented as examples. First, two kinds of diodes association in a power converter are presented, illustrating the impact of such impedance on the diodes operation. Each converter is designed for a 200 V DC bus voltage, the current per diode can be set up to 300 mA (750 A/cm^2). A converter using diode parallelization and a multiphase converter are then compared in this way. Second, a small diode of the device is used as a thermosensitive parameter to have online temperature information when others diodes of the device are used for power conversion, it is shown that this diode temperature sensor is affected by the others diodes due to this shared impedance. Finally, a novel diode device architecture (simulations and experiments) is presented in the way to decouple the current path of diodes by using electrical isolation. This kind of architecture can be used for each application requiring one or some diodes isolated from the other ones. This method can also be used for transistors device designs.
[1] D. Eon, A. Traore, J. Pernot, and E. Gheeraert, Proc. ISPSD, vol. 2016-July, pp. 55–58, 2016.
[2] H. Umezawa, Y. Kato, and S.-I. Shikata, Appl. Phys. Express, vol. 6, no. 1, 2013.
[3] A. Traoré, P. Muret, A. Fiori, D. Eon, E. Gheeraert, and J. Pernot, Appl. Phys. Lett., vol. 104, no. 5, p. 052105, 2014.
4:15 PM - EM06.09.03
Boron-Doped Diamond Multilayers—New Approach towards High Blocking Voltage Devices
Alexandre Fiori 1 , Tokuyuki Teraji 1
1 , National Institute for Materials Science, Tsukuba Japan
Show AbstractDiamond is often described as the ultimate semiconductor for high power electronic devices able to work in harsh environments. Since few decades, investigations on have been focused on methods able to combine large blocking voltage and forward current in diamond Schottky diodes. Therefore, the most significant reduction of serial resistance has been reached by designing pseudo-vertical and vertical architectures, where heavily boron-doped substrate/epilayer is used as conductive pathway [1]. However, only Schottky diodes based on lateral architectures, which do not require heavily boron-doped layers, broke records of blocking voltages. The most probable origin of poor blocking voltages could be coming from crystalline defects such as dislocations triggered by heavily boron-doped diamond layers [2].
In this study, we fabricated unique boron-doped diamond multilayers for Schottky diodes, and we evaluated their electrical properties. We deposited successively heavily boron-doped and undoped diamond layers with thicknesses calibrated to avoid the emergence of dislocations. To do so, a special diamond growth process has been developed with the sequential addition of methane, oxygen, and trimethylboron to the feed gas. That particular plasma-enhanced CVD has been monitored by optical emission spectroscopy (OES) [3]. We found strong correlations between boron doping profiles measured by SIMS and time-resolved plasma diagnostics, which gave the opportunity to use OES as an in-situ characterization tool. Afterwards, lightly boron-doped carrier-drift layers have been deposited on boron-doped multilayers to create pseudo-vertical Schottky diodes. Finally, reverse blocking voltages and forward currents in our preliminary structures have been compared with conventional vertical-type or lateral-type diamond Schottky diodes.
References:
[1] A. Fiori, T. Teraji, and Y. Koide, Appl. Phys. Lett. 105, 133515 (2014)
[2] M.P. Alegre, D. Araujo, A. Fiori et al., Appl. Phys. Lett. 105, 173103 (2014)
[3] A. Fiori, T. Teraji, Diamond Relat. Mater. 76, 38-43 (2017)
4:30 PM - *EM06.09.04
Homoepitaxial Diamond Films Growth for Electronic Device Application
Tokuyuki Teraji 1
1 , National Institute for Materials Science, Tsukuba Japan
Show AbstractIn this decade, studies on semiconducting diamond for the power device application have intensively been conducted in several research groups. A use of diamond crystals with low defect density is crucial for obtaining high blocking voltage. High crystalline quality and high purity of diamond crystals are also requested in the field of research on quantum information/sensing using diamond. Although a lot of effort was devoted to improve the quality of diamond films, dislocations still remain in the crystals with the number density higher than 104 cm-2. In this study, we propose advanced diamond growth condition that removes crystalline defects effectively during the growth process of homoepitaxial diamond films.
Homoepitaxial diamond films were deposited on Ib(100) substrates using the homebuilt microwave plasma-assisted chemical-vapor-deposition apparatus [1]. In this study, effect of oxygen addition during diamond growth was investigated [2]. By optimizing growth conditions with higher oxygen concentration of 2%, high-purity homoepitaxial (100) diamond layers, typical nitrogen concentration of which was less than 1 ppb, were successfully grown. Cathodoluminescence mapping and 3D Raman measurements indicated a number density of dislocations in the homoepitaxial layer is typically 104-105 cm-2. Tungsten carbide Schottky electrodes fabricated on the non-doped diamond showed high blocking voltage of 2.2 kV. This diamond films growth technique is promising for designing high-performance quantum information devices.
References:
[1] T. Teraji, T. Yamamoto, K. Watanabe, Y. Koide, J. Isoya, S. Onoda, T. Ohshima, L. J. Rogers, F. Jelezko, P. Neumann, J. Wrachtrup, and S. Koizumi, phys. stat. sol. (a) 212, 2365(2015).
[2] T. Teraji, J. Appl. Phys. 118, 115304(2015).
Symposium Organizers
Philippe Bergonzo, CEA Saclay
Timothy Grotjohn, Michigan State University
Mutsuko Hatano, Tokyo Institute of Technology
Christoph Nebel, Fraunhofer IAF
Symposium Support
Applied Diamond, Inc.
Arios Ltd.
CARAT Systems
CIVIDEC Instrumentation GmbH
Cline Innovations, LLC
DiamFab
ICDAT LTD.
Microwave Enterprises, Ltd.
Fraunhofer Center for Coatings and Diamond Technologies- Michigan State University
New Diamond Technology, LLC
Seki Diamond Systems
EM06.10: Sensing with NV Centers and Spin Coupling
Session Chairs
Wednesday AM, November 29, 2017
Hynes, Level 1, Room 108
8:30 AM - EM06.10.01
Assessment on Thermal Stability of Atomic Orientation of N-V Axis Using Perfectly-Aligned NV Ensembles
Hayato Ozawa 1 , Hitoshi Ishiwata 1 , Takayuki Iwasaki 1 , Mutsuko Hatano 1
1 , Tokyo Institute of Technology, Tokyo Japan
Show AbstractPerfectly aligned high density nitrogen – vacancy (NV) center is important for macroscopic applications that require high contrast and S/N ratio to realize high magnetic sensitivity. Large detection volume with a thick CVD film (>100 μm) is expected to achieve a magnetic sensitivity of pico- to femto-tesla range, required for biological/medical applications such as magneto-encephalography and MRI. However, the perfectly aligned N-V axis for the high contrast may be disrupted by thermal migration of vacancies of the NV centers [1] during long growth time for the high thickness. Thus, understanding thermal stability of the orientation of the N-V axis is crucial in the long time deposition of the diamond sensor. Here, we investigated thermal stability of the NV centers by annealing perfectly aligned NV ensemble at high temperature and evaluated the alignment ratio. Furthermore, we estimated an activation energy of the re-orientation of NV centers.
In order to form perfectly aligned NV ensemble, we have grown N-doped diamond on Ib (111) diamond substrate by MPCVD using CH4 / H2 as source gasses [2]. During the growth, N2 gas was introduced to form the NV centers. After confirming the perfect alignment, the sample was annealed at 1150 °C for total of 480 minutes. The alignment ratio was evaluated at nine different steps up to 480 minutes by optically detected magnetic resonance (ODMR) measurements.
Before the annealing, NV ensemble showed signal only along [111] direction (NV//[111]) in the ODMR spectrum, indicating the perfectly alignment along one direction. The ODMR signal from both NV//[111] and NV centers oriented along other directions appeared after annealing. Therefore, NV//[111] were changed the orientation by thermal energy of annealing. The alignment ratio for [111] direction decreased as increasing the anneal time and saturated at 25 % after 480 minutes. From this result, we estimated the activation energy for re-orientation of NV centers to be 4.8 eV. This value is comparable to calculated energy (4.8–4.9 eV) reported in the previous literature [1]. This activation energy is important for design of growth conditions of the diamond sensor. For example, the high growth temperature such as 1050 °C [2,3] can not maintain perfectly aligned NV//[111] (>90 %) for more than 3 h in calculation using this activation energy. Hence, high growth rate is required. In contrast, the low growth rate is accepted in the lower temperature growth (≤900 °C) [2,4] that hardly changes the N-V orientation. Therefore, contriving pair of growth temperature and rate is important to target thickness and alignment ratio by the estimation using the re-orientation activation energy.
Acknowledgements
This work was supported by CREST, JST.
[1] H. Pinto, et al., Phys. Status Solid A 209, 1765 (2012).
[2] H. Ozawa, et al., Appl. Phys. Express 10, 045501 (2017).
[3] J. Michl, et al., Appl. Phys. Lett. 104, 102407 (2014).
[4] T. Fukui, et al., Appl. Phys. Express 7, 055201 (2014).
8:45 AM - EM06.10.02
CVD Growth Formation of Perfectly Aligned High Density Delta Dope NV Center Film for Wide Field Imaging of Nano-NMR
Makoto Nakajima 1 , Hitoshi Ishiwata 1 , Takayuki Iwasaki 1 , Mutsuko Hatano 1
1 , Tokyo Institute of Technology, Meguro-ku Japan
Show AbstractPerfectly aligned high density delta doped nitrogen vacancy (NV) center film represents an ideal material for wide field quantum magnetometery. The alignment of the NV center allows NV center ensemble with a high signal/noise ratio combined with the high contrast to be formed uniformly over wide area. Confinement of the delta doped NV centers within 10nm from the surface allows nanoscale NMR measurement with extremely small volume. This technique combined with perfectly aligned NV ensemble allows nanoscale analysis on large sensing targets such as Membrane protein. In this study, a perfectly aligned high density NV center delta doped layer was formed by step-flow growth using chemical vapor deposition (CVD) system[1].
Prior to fabrication of a delta doped layer, intrinsic diamond layer was grown by CVD on a IIa diamond (111) substrate with a 2 degrees off angle in the [-1-12] direction using CH4/H2(0.05%) mixed gas. Finally, a delta doped layer containing high concentration of nitrogen was formed by introducing 0.4% of nitrogen (growth time: 30, 60, 120 seconds). Step-flow growth was obtained by low methane concentration of 0.05% for the alignment of the NV centers. Formation of NV center ensembles were confirmed from the measurement of the emission intensity by the confocal microscope. Photon counts obtained from the NV centers indicated the presence of 6.1 × 1015-3.1 × 1016 cm-3 NV centers, a density one hundred times higher than previous reports[2,3]. SIMS measurement on delta doped NV center with growth time of 30 second shows highly concentrated nitrogen layer exceeding 1019 cm-3 within 10 nm from the surface. Background level of nitrogen (< 5 × 1016 cm-3) from the intrinsic layer was also confirmed from SIMS measurement for confinement of NV center within 10nm from the surface. The optically detected magnetic resonsnace (ODMR) measurement confirms alignment ratio of more than 99% for perfect alignment of NV centers.
Finally, nanoscale NMR measurement was performed using the XY8 pulse sequence. The nuclear spin signal of hydrogen in immersion oil and fluorine in fomblin oil was detected to demonstrate surface-sensitive nuclear spin detection and the effective depth of the NV center was estimated. Thus, a route for material control of shallow NV centers has been developed by step-flow growth using a CVD system.
Acknowledgements
This work was supported by CREST, JST and JSPS KAKENHI Grant (No. JP17H01262)
[1] H. Ishiwata, M. Nakajima, et al., Arxiv 1704.03642 (2017).
[2] K. Ohashi, et al., Nano Lett. 13, 4733 (2013).
[3] C. Osterkamp, et al., Appl. Phys. Lett. 106, 113109 (2015).
9:00 AM - EM06.10.03
Technique for Super-Resolution Imaging and Individual Readout of Solid-State Defect Centers
Eric Bersin 1 , Michael Walsh 1 , Sara Mouradian 1 , Matthew Trusheim 1 , Tim Schroeder 1 2 , Dirk Englund 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Niels Bohr Institute, University of Copenhagen, Copenhagen Denmark
Show AbstractA central goal in quantum information science is to establish entanglement across multiple quantum memories. In the area of semiconductor quantum optics, a leading system is the nitrogen vacancy (NV) center in diamond [1], which allows access to a spin center that can be entangled to multiple nuclear spins. Recently, super-resolution imaging techniques have been developed to improve the spatial resolution in NV sensing applications [2]. Such techniques could also benefit quantum information processing by allowing individual spin control in mesoscopic spin systems. Here, we introduce a technique to individually initialize and measure NV centers within small ensembles of magnetically coupled spins. The technique relies on optical addressing of spin-dependent transitions and makes use of the natural inhomogeneous distribution of emitters resulting from strain in the diamond lattice [3]. Our protocol applies to a wide-range of defect centers beyond NVs. Unlike previously presented super-resolution techniques, our approach allows readout of individual spins with minimal perturbation to the other qubits in the ensemble. This method thus provides potentially greater efficiency in quantum sensing protocols and opens the door to a broader class of quantum information algorithms with multi-qubit coupled spin systems in solids.
References:
[1] P.C. Maurer et al. Room-temperature quantum bit memory exceeding one second. Science 336, 6086 (2012).
[2] J.-C. Jaskula et al. Superresolution optical magnetic imaging and spectroscopy using individual electronic spins in diamond. Opt. Express 25, 11048 (2017).
[3] M. Trusheim and D. Englund. Wide-field strain imaging with preferentially aligned nitrogen-vacancy centers in polycrystalline diamond. New J. Phys. 18, 123023 (2015).
9:15 AM - EM06.10.04
Optically Induced Cross Relaxation via Nitrogen Vacancy Centers for Bulk Diamond C-13 Hyperpolarization
Ralf Wunderlich 1 , Jonas Kohlrautz 2 , Bernd Abel 3 , Juergen Haase 2 , Jan Meijer 1
1 Nuclear Solid State Physics, Leipzig University, Leipzig, Saxony, Germany, 2 MQF, Leipzig University, Leipzig Germany, 3 , Leibniz-Institute of Surface Modification, Leipzig Germany
Show AbstractNuclear Magnetic Resonance has become a widely used technique with applications in many fields, e.g., structure analysis in chemistry and Magnetic Resonance Imaging in medicine. Often, sensitivity can become an issue due to the weak interaction of nuclear spins with the applied magnetic field. To overcome this, numerous techniques, e.g., cross polarization between different spin species, have been developed to increase the polarization of the nuclear spin system above the one given by the Boltzmann distribution in thermal equilibrium.
In our experiments, the negatively charged Nitrogen Vacancy center (NV) in diamond is used to polarize C-13 nuclei in a bulk single crystal. Due to a yet to be explained mechanism, the C-13 nuclei are polarized by a NV center that is prepared in a m = 0 ground state just by shining green light on it near the excited level anti crossing (ESLAC) at about 50 mT.
For this reason, we designed a home-build low field irradiation unit and a shuttling system to the NMR measurement probe in a 7 Tesla solenoid. This enables us to investigate C-13 spins in the whole sample – also those which are far away from the NV defect. At optimal conditions, we obtained an increased signal to noise ratio in about two minutes which corresponds to about a full day standard measurement without hyperpolarization.
In order to explain the findings, we propose a model with a C-13 nucleus that is part of a NV center nearby. An additional coupling of this quantum system to a P1 center in proximity leads to cross polarization. Within this model, based on hyperfine couplings from literature, we are able to reproduce the observed field-dependent hyperpolarization (intensity and sign) of the bulk with high accuracy. As a consequence, we are able to reproduce the narrow field dependence of the C-13 hyperpolarization that differs tremendously from the ODMR of a single NV center.
9:30 AM - EM06.10.05
Quantum Sensing System for Large Detection Volume with Ensemble Nitrogen-Vacancy Centers
Yuta Masuyama 1 , Hayato Ozawa 1 , Yuji Hatano 2 , Takayuki Iwasaki 1 , Mutsuko Hatano 1
1 Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, Tokyo, Meguro, Japan, 2 Institute for Protein Research, Osaka University, Osaka Japan
Show AbstractLarge detection volume with ensemble nitrogen-vacancy centers is expected to achieve a magnetic sensitivity of femto-tesla range, required formedical applications. There are three critical factors to achieve precise magnetic sensing: (1) Selective alignment of a high amount of nitrogen-vacancy (NV) centers. (2) Optical power of approximately 4.5 GW/m2 to excite NV centers (3) Microwave field with inhomogeneity less than 10% to uniformly drive NV centers. Recently, we have reported the formation of perfectly aligned and high-density ensemble of NV centers along the [111] direction [1]. The magnetic sensor with 2.2 mm diameter and 5 μm in thickness of the high-density NV ensemble can potentially achieve a shot noise limited sensitivity of approximately 90 femto-tesla. However, it is hard to perform efficient manipulation of the high amount of electronic spins and to obtain the NV fluorescence efficiently with the conventional confocal microscope system. In this study, we implemented more efficient microwave and optical systems for the perfectly aligned NV ensemble along the [111] direction.
Our device consists of the diamond sensor on compound parabolic concentrator (CPC) [2], microwave circuit, and DC-magnetic coil in a compact frame made by 3D printer. This configuration enables us to apply microwave field perpendicular to the NV axis, and apply DC-magnetic field parallel to the NV axis without interfering the laser beam. The diamond sample was placed at the center of microwave circuit and the DC-magnetic coil, leading to more uniform microwave and magnetic fields than those in the conventional setup consisting of a microwave wire and a coil. We used diamond samples containing CVD-grown perfectly-aligned NV centers (~1016 cm-3). One sample was exposed to electron beam irradiation with a dose of 3.7×1017 cm-2, leading to a NV density of ~5 × 1018 cm−3.
We performed pulse optically detected magnetic resonance (ODMR) measurements. The Rabi oscillation of 5MHz was observed from the ensemble NV centers, which is 10 times slower than that obtained by confocal microscope. Spin echo measurement resulted in a spin relaxation time (T2) of 2 μs, in agreement with that obtained in the confocal measurement. We found that initialization time with 3 W input laser was about 500 μs which was 100 times slower than that with the confocal microscope with about 5 mW input laser. Thus, we will improve the efficient setup based on the mentioned results to obtain the higher frequency Rabi oscillation and higher optical power density for the NV ensemble.
This work was supported by CREST, JST and JSPS KAKENHI Grant (No. JP17H01262).
[1] H. Ozawa et al., Appl. Phys. Express. 10, 045501 (2017)
[2] T. Wolf et al., Phys. Rev. X 5, 041001 (2015)
EM06.11: Sensors and Devices
Session Chairs
Wednesday PM, November 29, 2017
Hynes, Level 1, Room 108
10:15 AM - *EM06.11.01
Low Workfunction Diamond Surfaces for Thermionic Applications
Paul May 1
1 , Bristol University, Bristol United Kingdom
Show AbstractThermionic energy conversion (TEC) is a method of power generation involving the conversion of heat into electricity. The heat source can be from waste heat generated from mechanical equipment, such as engines, or from solar radiation being concentrated and focused by a parabolic reflector. TEC can produce electrical power cleanly and efficiently, and with few moving parts it requires minimal maintenance. A TEC convertor consists of two parallel electrodes, one heated (the emitter) and one colder (the collector) separated by a vacuum gap of a few microns or mm. If the collector is heated to a temperature such that the electrons can overcome the potential barrier (workfunction) to escape the surface, electrons will be emitted and travel across the gap to the collector where they will be absorbed. If the electrodes are instead connected via an external circuit and a load, on completing the circuit, electrons will flow back to the emitter, delivering electrical power to the load.
The efficiency of TEC depends crucially on the magnitude of the surface workfunction of the emitter. For most materials, including metals, this workfunction is usually a few eV, which means that the temperatures required for electron emission can be 1500-2000°C. However, diamond is an almost unique material, in that its surface has a low or even zero workfunction, or more accurately, a ‘negative electron affinity’ (NEA), as a result of the surface dipole created by C-H bonds on its terminating surface. The NEA diamond surface allows TEC to begin at temperatures as low as 500°C, and give significant emission currents (10s of mA) at temperatures of 800°C or more.
The main issue currently holding back this technology is that the hydrogen layer bonded to the diamond surface desorbs at temperatures >700°C. For the past 5 years or more, various research groups have been pioneering a new approach to this problem which uses a monolayer or sub-monolayer of a metal oxide as the NEA layer on diamond. The diamond surface is first oxidised, and then a few nm of a metal, such as lithium, is evaporated onto it and annealed to chemically bond with the oxygen. Preliminary results with Li-O and Mg-O diamond surfaces show excellent TEC properties and high-temperature stability, preliminary computer simulations by ourselves and others predict that other metal oxide layers should surpass these.
In this talk we shall review the field of metal-oxide terminations for low workfunction diamond surfaces, and evaluate recent theoretical and experimental results reported for a range of metal-oxide terminations, with respect to their use as diamond-based thermionic devices. We shall also discuss the prospects for further improvement in the NEA layers using oxides of metals such as Al, Ti, Co, Ta, Sc, V, Ni, Zn and V, and outline strategies for both modelling them computationally and depositing them experimentally.
11:00 AM - EM06.11.03
UV Photodetector Improvements on Unpolished Polycrystalline CVD Diamond
Joe Welch 1 , Steven Evans 1 , Richard Jackman 1
1 , University College London, London United Kingdom
Show AbstractDiamond's wide band gap (5.5eV) makes it ideal as an optically blind UV photodetector. High purity diamond starts to show photoconductive behaviour from UV wavelengths below about 236nm, which is slightly above the band gap wavelength of 225nm. In this work freestanding polycrystalline diamond is grown using MPECVD and interdigitated electrodes are patterned onto the diamond surface using standard lithography techniques. Repeated methane and air anneals are used to reduce the detectors response in the visible and also to reduce surface conductivity that is caused by hydrogen terminated carbon atoms on the surface. There are numerous problems to be overcome in using polycrystalline diamond as a UV photodetector. Inhomogeneities across the surface caused by varying grain sizes and the presence of grain boundaries complicate the use of polycrystalline diamond for imaging purposes. The surface roughness also increases the difficulty of patterning the interdigitated electrodes. The surface can be smoothed using polishing methods, but this can induce subsurface damage that produces trapping centres. These trapping centres can cause the response of the detector to react slowly to a change in the UV illumination. To this end, methods to reduce surface roughness without the need for polishing are explored and the resulting photoconductivity measured.
11:15 AM - EM06.11.04
Multi-Electrode Sensing from BDD Arrays for Advanced Analytical Detection in Complex Fluids
Philippe Bergonzo 1 , Bacem Zribi 1 , Emmanuel Scorsone 1
1 , CEA, LIST Diamond Sensors Laboratory, Gif Sur Yvette France
Show AbstractBoron Doped Diamond is an innovative electrode material in particular in terms of robustness, potential for miniaturisation and sensitivity. Its application in electrochemistry leverages numerous assets, and namely a wide electrochemical window in aqueous media, high corrosion resistance, chemical inertness, biocompatibility and low background current.
In order to enhance the reactivity of the BDD electrodes towards a wider range of chemical compounds, we have optimized an innovative method for the deposition of catalyst based nanoparticles on the electrode surfaces from transition metals such as platinum, iridium etc and their corresponding alloys. Their characteristics in terms of size, oxidation levels, and adhesion were well characterized to ensure high stability and reproducibility. These nanoparticles exhibit an interesting electro-catalytic activity and open the way to the detection of products derived from enzymatic reactions, pesticides or many other electrochemically non-active species.
Based on this approach, we developed a multi-sensor detection system composed of several BDD electrodes each functionalized using a different catalyst metal in the form of nanoparticles. Each functionalized electrode exhibits a specific sensitivity when exposed to an unknown product. From the fine complementarity of an array of such electrodes, it becomes possible to obtain a characteristic chemical fingerprint of the product to detect. By assembling several of such sensors, and coupling them with algorithmic learning / recognition methods, the system provides an improved selectivity, in a similar way to an “electronic tongue”. This was applied to several case studies, including the detection of hydrogen peroxide, food contaminants such as scatol or indole, and pesticides including paraoxon and imidaclopride.
11:30 AM - EM06.11.05
Single Crystalline Boron-Doped Diamond Superconducting Quantum Interference Devices
Ikuto Tsuyuzaki 1 , Taisuke Kageura 1 , Masakuni Hideko 1 , Yousuke Sasama 2 , Takahide Yamaguchi 2 , Yoshihiko Takano 2 , Minoru Tachiki 2 , Shuuichi Ooi 2 , Kazuto Hirata 2 , Shunichi Arisawa 2 , Hiroshi Kawarada 1 3
1 , Waseda University, Tokyo Japan, 2 , National Institute for Materials Science, Tsukuba Japan, 3 , The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Nishiwaseda Japan
Show AbstractSuperconducting quantum interference device (SQUID), which is composed of superconductive loop with one or two Josephson junctions, is widely used as high sensitive magnetometers. One of the problem of SQUID is a durability of the superconducting materials. The materials used for SQUID such as Niobium (Nb) or YBa2Cu3O7 are fragile and weak against oxidation and heat. On the other hand, diamond is hard and resistant to these properties. The transition temperature Tc of (111) diamond with boron concentration [B]=8×1021 cm-3 is 10K, whose value is equivalent to that of Nb. And the Tc of diamond can be controlled by changing [B] and lattice orientation [1]. Therefore, diamond is a promising material for robust superconducting devices. Recently we reported a single crystalline diamond Josephson junction with a step-edge structure [2]. The junction has weak-link structure formed on the boundary between (111) and (001) diamond. However, we revealed that the operating temperature is limited to below 4K, whose value corresponds to the Tc of (100) step region. So the purpose of this study is to demonstrate single crystalline diamond SQUID with the step-edge structure and to explore another fabrication process in order to increase an operation temperature of diamond SQUID.
From the SQUID’s temperature dependence of resistivity, two superconducting transition points 9K and 3.5K were observed. These values seem to correspond to the Tc of (111) and (001) diamond, respectively. The critical current (Ic) was 0.32 mA and IcRn was 0.32 mV at 2.6K. The observed I-V curve is called over-dumped type, which indicates the Josephson junction is caused by weak-link structure. From the magnetic field measurement at 2.6K, the voltage of the SQUID oscillated as a function of the magnetic field with a period of 2.9 μT. This is close to 2.0 μT theoretically calculated from the SQUID size and flux quantum Φ0=2×10-15 Wb.
To increase operation temperature, we also fabricated some Josephson junctions with Dayem bridges or boundaries using only (111) diamond. These junctions had weak-links from tens to hundreds nanometers (nm) fabricated by electron beam lithography and reactive ion etching or re-growth. In this study, we fabricated the Dayem bridge junction structure with 400 nm width and 200 nm length. The resistance started to drop sharply around 10K and Tc (zero) was 6K. Thus, Tc of the bridge part is considered to be lower than bulk. I-V characteristic like DC Josephson effect with no hysteresis under 6K is observed. Ic was 0.14mA and IcRn was 0.014 mV at 4.5K.
We confirmed the operation of the SQUID with the step-edge Josephson junctions by observing the modulation voltage. And we also challenged to establish new fabrication process of diamond Josephson junction such as the Dayem bridge structure and the re-growth boundary to enhance operating temperature.
[1] A.Kawano, H. Kawarada et al., PRB 82 (2010) 085318.
[2] M. Hideko, H. Kawarada et al., MRS Fall 2016
11:45 AM - EM06.11.06
Radiation Hardness of Hydrogen-Terminated Diamond Transistor and Diode Structures
David Shahin 1 , Kiran Kovi 2 , Matthew Yung 1 , Yizhou Lu 1 , Alexander Yuan 1 , Aaron Auerbach 1 , Aayush Thapa 1 , Ilya Ponomarev 2 , James Butler 2 , Aristos Christou 1
1 , University of Maryland, College Park, Maryland, United States, 2 , Euclid Techlabs, Gaithersburg, Maryland, United States
Show AbstractDiamond exhibits a number of material properties ideal for future power and RF electronics applications, including an ultra-wide bandgap (5.5 eV), a high breakdown field (>10 MV/cm), high theoretical room-temperature carrier mobility (>3800 cm2/V*sec), extremely high thermal conductivity (>22 W/cm*K), excellent mechanical properties, and excellent resistance to radiation damage compared to other semiconductors [1]. However, diamond doping is problematic, as typical dopants (B, P) have very high activation energies (>0.37 eV), leading to low dopant activation efficiency [2]. This drawback has been, in part, mitigated by two-dimensional conductivity found in hydrogen-terminated diamond surfaces. Hydrogen termination via exposure to hydrogen plasma creates a surface C-H dipole layer that reduces the carrier ionization energy by nearly 1.5 eV. Adsorbed species, such as atmospheric H2O, NO2, or intentionally-introduced passivation species contact this dipole layer, and together generate a near-surface two-dimensional hole gas (2DHG) with carrier densities of 1013-1014 holes/cm2 [3].
The radiation damage tolerance of these surface 2DHG layers has not yet been significantly studied. Verona, et al. recently showed that hydrogen-terminated diamond field effect transistors are radiation hard with respect to non-ionizing neutrons [4]. However, these structures may be susceptible to ionizing radiation damage due to disruption of the surface adsorbates or passivation layers, and thus the 2DHG. In this work, we will present our work on the material processing, fabrication, and characterization of diamond field effect transistors and Schottky diodes in preparation for irradiation. Diamond substrates grown by high pressure high temperature (HPHT) synthesis have been specially prepared to produce defect-free, ultra-smooth diamond surfaces prior to hydrogen termination and device fabrication. Devices fabricated via multiple processing routes for generation of the 2DHG, including simple atmospheric adsorbates, intentional NO2 adsorption, and passivation with dielectrics such as Al2O3, will be compared. We will then describe the effect of ionizing radiation species (particularly gamma rays and electrons) on the output characteristics of these devices in order to explore their reliability in high radiation environments.
[1] A. Ionascut-Nedelcescu, et al., IEEE Trans. Nucl. Sci. 49(6), 2733-2738 (2002).
[2] D.A.J. Moran, et al., IEEE Elect. Dev. Lett. 32(5), 599-601 (2011).
[3] M. Kubovic, et al., Diam. Relat. Mater. 18(5-8), 796-799 (2009).
[4] C. Verona, et al., IEEE Elect. Dev. Lett. 37(12), 1597-1600 (2016).
*The effort depicted was or is sponsored by the Department of Defense, Defense Threat Reduction Agency under Grant No. HDTRA1-17-1-0007. The content of this information does not necessarily reflect the position or the policy of the federal government, and no official endorsement should be inferred.
EM06.12: Catalytic Applications
Session Chairs
Wednesday PM, November 29, 2017
Hynes, Level 1, Room 108
1:45 PM - EM06.12.01
Transition-Metal Functionalized Nanodiamond for Photocatalytic Applications
Benjamin Kiendl 1 , Guillaume Levitre 2 , Emina Hadzifejzovic 3 , Mailis Lounasvuori 3 , Amelie Venerosy 4 , Sneha Choudhury 5 , Tristan Petit 5 , Emad Aziz 5 , Karin Larsson 6 , Hugues Girard 4 , Jean-Charles Arnault 4 , John Foord 3 , Geraldine Masson 2 , Anke Krueger 1
1 , Wuerzburg University, Wuerzburg Germany, 2 , Institut de Chimie des Substances Naturelles, Gif-sur-Yvette France, 3 , University of Oxford, Oxford United Kingdom, 4 Diamond Sensors Laboratory, CEA LIST, Saclay France, 5 , Helmholtz-Zentrum Berlin, Berlin Germany, 6 , Uppsala University, Uppsala Sweden
Show AbstractPhotocatalyzed transformations are of high importance as they provide the opportunity to chemically store energy in the form of solar fuels produced from CO2 using solar light. Furthermore, the photocatalytic transformation of organic starting materials is equally attractive as such reactions produce little to no waste, can be carried out under benign conditions and solar energy can be used for the transformation. It has been reported that diamond is an attractive material for the photocatalytic reduction e.g. of carbon dioxide due to its unique electronic structure.1 However, the large bandgap requires UV light for a direct excitation of valence electrons. Therefore, the introduction of unoccupied states in the band gap of diamond using a suitable surface functionalization is one way to overcome this limitation for the direct use of visible light.
In this work we report on the synthesis of a bi-functionalized linker molecule and its subsequent grafting onto diamond nanoparticles, followed by the immobilization of different ruthenium complexes on these linkers using the concept of click-chemistry. The resulting conjugates have been characterised using various spectroscopic methods including Raman, FTIR, XPS, synchrotron-based x-ray absorption spectroscopy and theoretical insights into the electronic structure of the conjugates are given by quantum mechanical calculations.
The resulting nanodiamond conjugates showed their applicability in the photocatalytic transformation of carbon dioxide to solar fuels such as methanol and formate in aqueous media as well as in organic photocatalyzed reactions such as the aza Friedel-Crafts reaction. Additionally, the influence of the linker architecture on the catalytic and electronic properties will be discussed.
This project has received funding from the European Union's Horizon 2020 Program under Grant Agreement no. 665085 (DIACAT).
References
1 Zhu, D.; Zhang, L.; Ruther, R.; Hamers, R. Nature Materials 2013, 12, 836-841.
2:00 PM - EM06.12.02
Metal Nanostructures Embedded in Diamond for Enhanced Photocatalytic Activity
Shuo Li 1 , Robert Hamers 1
1 , University of Wisconsin-Madison, Madison, Wisconsin, United States
Show AbstractMetallic nanostructures with plasmonic properties were synthesized into diamond with an in-situ growth method, which enhanced the photocatalytic activity of diamond significantly. Diamond is well known for its good mechanical robustness and extreme chemical stability. One unusual property of diamond is that when the diamond surface is terminated with hydrogen, its conduction-band edge lies ~0.8-1.3 eV above the vacuum level. This means that when electrons in the valence band of diamond are excited to the conduction band, they can diffuse to the surface and be directly emitted into adjacent environment with negligible barrier. When the diamond surface is in contact with water, the electrons ejected into water will become solvated electrons, which are highly reducing agents and can initiate many reactions like N2 reduction that are inaccessible to most common semiconductors. Previously we have successfully demonstrated the photoelectrochemical reduction of N2 to ammonia using diamond, however, diamond still needs many improvements to become an efficient material for photoelectrochemistry. One is the large bandgap limits diamond utilization of light smaller than 225 nm, the other is the poor light absorption ability leads to insufficient use of photons. Here we demonstrate that by incorporating plasmonic metal nanostructures into diamond, the optical properties of diamond can be tuned, resulting in enhanced photocatalytic activity of diamond.
The plasmonic nanoparticles can be observed by cross-section scanning electron microscope, with uniform size of 30 nm. Diffuse-reflective spectra clearly show the plasmonic peaks, which is in good correspondence of SEM. Photoelectron emission measurement of the plasmonic diamond film indicates higher photocurrent and clear sub-bandgap photoelectron emission, which is the result of higher light absorption and possible hot electron generation from plasmonic nanostructures. N2 reduction ability of plasmonic diamond film and pure diamond are also compared, and plasmonic diamond film composite exhibits higher NH3 yield under full spectrum wavelength light, and higher sub-bandgap N2 reduction ability. Our results indicate that by using the facile in-situ synthetic method, metal nanostructures can be formed in diamond and the diamond optical properties can be tuned, resulting in higher photocatalytic performance.
2:15 PM - EM06.12.03
Negative Electron Affinity Diamond Surfaces for Photoelectrochemical Reduction of Perfluoroalkyl Substances
Noah Plymale 2 , Scott Walton 1 , Tatyana Feygelson 4 , Gary Kushto 3 , Bradford Pate 4
2 Chemistry, National Research Council Postdoctoral Associate, Washington, District of Columbia, United States, 1 Plasma Physics, U.S. Naval Research Laboratory, Washington, District of Columbia, United States, 4 Chemistry, U.S. Naval Research Laboratory, Washington, District of Columbia, United States, 3 Optical Sciences, U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractPerfluoroalkyl substances (PFAS), used in commercial coatings and as essential components of firefighting foams, have been identified by the U.S. Environmental Protection Agency as pervasive environmental contaminants that bioaccumulate and pose a potentially serious health risk. The robust chemical stability of PFAS severely impedes their natural degradation, and light PFAS are not effectively removed by conventional water filtration technology. Degradation of PFAS by electrochemical reduction with solvated electrons could provide an efficient and clean pathway to purify water containing PFAS. Hydrogen-terminated diamond surfaces are known to exhibit a negative electron affinity (NEA), and solvated electrons photochemically produced at illuminated H-terminated diamond interfaces have been demonstrated to reduce N2 to NH3 and CO2 to CO in water. In this work, hydride-, amino-, and alkyl-terminated diamond surfaces, all of which exhibit NEA, are prepared, and their respective vibrational and electronic structures are determined. The behavior of the electron affinity as a function of gradual oxidation of the surface in air and in aqueous environments is investigated. The suitability of diamond electrodes terminated by hydride, amino, and alkyl substituents as sources of solvated electrons for the purification of water contaminated by PFAS will be discussed.
EM06.13: Surface Transfer and Electronic Devices
Session Chairs
Wednesday PM, November 29, 2017
Hynes, Level 1, Room 108
3:30 PM - *EM06.13.01
Controlling the Stability of Diamond's Surface Conductivity
Travis Wade 1 , Charles Wuorio 1 , Michael Geis 1 , Joseph Varghese 1 , Theodore Fedynyshyn 1 , Steven Vitale 1 , Mark Hollis 1
1 Advanced Technology Division, Massachusetts Institute of Technology Lincoln Laboratory, Lexington, Massachusetts, United States
Show AbstractAfter many years of development, AlGaN/GaN 2-D electron-gas FETs have revolutionized the power RF field. With a similar development effort to harness its superior semiconductor properties, diamond is expected to enable devices with an order of magnitude increase in performance. Primary among the development challenges is a stable, high conductivity active FET channel.
Hydrogen-terminated diamond, with the appropriate surface treatment, forms a 2-D hole gas at its surface. Electron acceptors (NO2, O3, and Cl2) increase the conductance while electron donors (NH3 and NH2C6H5) diminish the conductance. All these surface dopants are unstable in air with their properties diminishing in time.
We report a different doping approach using UV-generated free radicals. We theorize that these radicals abstract hydrogen from the diamond surface and insert themselves at that site. The resulting surface has stability comparable to ALD-deposited Al2O3 and conductivity comparable to the most effective surface treatments reported to date.
Surface conductivity was measured with a Hall – Van der Pauw system to quantify carrier type, density, and mobility. The enhanced conductivity is often observed to be the result of increased carrier mobility instead of increased carrier density. These results indicate that a model of diamond surface conductivity that only considers the dopants as negatively charged states to generate holes is incomplete.
We have also explored the impact of variations in physical properties on surface conductivity. We will report on the relative impacts of surface roughness, sub-surface polishing damage, chemical purity, bulk stress, and growth method.
This presentation will discuss our work on free-radical-doped diamond surfaces and efforts toward maximizing the conductivity and stability.
4:00 PM - EM06.13.02
Controlling the Vanadium Oxidation State for Hole Accumulation at the Diamond/V2O5 Interface
Yichen Yao 1 , Yu Yang 1 , Xingye Wang 1 , Franz Koeck 1 , Robert Nemanich 1
1 , Arizona State University, Tempe, Arizona, United States
Show AbstractSurface transfer doping of hydrogen terminated diamond has been demonstrated with high work function transition metal oxides such as V2O5 and MoO3. In this study, vanadium pentoxide is employed as the charge transfer transition metal oxide material, and in situ x-ray and UV photoemission spectroscopy are employed to characterize the surface and interface properties. The electrical properties are characterized with Hall effect measurements. The goal of this study is to establish the effect of the vanadium oxidation state on the hole accumulation layer. Electron beam deposition was used to grow a thin layer of partially oxidized vanadium oxide on B-doped (001) diamond. An oxygen plasma treatment transformed the mixed V/V2O3/VO2 to fully oxidized state, V2O5. In situ XPS was used to establish the V oxidation state which is determined from the binding energy of the V2p3/2 core level. Similarly, the carbon 1s peak position is used to determine the band bending in the diamond. The results indicate essentially flat bands for the diamond / (V/V2O3/VO2), while upward band bending is observed after plasma oxidation to form a diamond/V2O5 interface. The process was repeated for oxygen terminated diamond (instead of H-terminated diamond) and results indicated that hydrogen termination of the B-doped diamond was more effective in achieving the surface conducting state of the diamond/V2O5 structure. The UV photoemission was used to monitor the vanadium oxide work function. It was found that the work function increased with the formation of V2O5 but then decrease with time after plasma oxidation. However, the interface properties appeared to be unchanged. The conducting behavior appears to be related to the uniformity of the oxidation state of vanadium oxide layer and whether the diamond surface is hydrogen terminated prior to oxide deposition.
This research is supported by a grant from MIT Lincoln Lab.
4:15 PM - EM06.13.03
Surface Transfer Doping of Diamond/MoO3 with an Al2O3 Interface Layer
Yu Yang 1 , Franz Koeck 1 , Xingye Wang 1 , Harshad Surdi 1 , Srabanti Chowdhury 2 , Robert Nemanich 1
1 , Arizona State University, Tempe, Arizona, United States, 2 , University of California, Davis, Davis, California, United States
Show AbstractSurface transfer doping on diamond provides an alternative strategy to enable high power and high frequency diamond FET operation. Recent studies have reported surface transfer doping on diamond using high electron affinity materials, such as MoO3, V2O5, WO3 and Nb2O5, as surface acceptors (Russell et al, APL 103, 202112 (2013)). Their lowest unoccupied molecular orbitals are below the valence band maximum of H-terminated diamond, such that electron transfer from the diamond to the oxides is energetically favorable. While a relatively high hole sheet concentration has been achieved, the hole mobility decreases using high electron affinity materials as surface acceptors. This decrease has been partially ascribed to the scattering of holes by ions in the acceptor layer. We propose to employ a thin layer of Al2O3 as an interface layer between diamond and MoO3 to increase the distance between the hole accumulation layer in diamond and ions in acceptor layer, and thus reduce the ionic scattering and increase the hole mobility. An ~2 nm Al2O3 layer was deposited by plasma enhanced ALD on hydrogen-terminated, undoped diamond (100) surfaces which was immediately followed by a remote hydrogen plasma treatment. A molybdenum layer was deposited using electron beam deposition, and the MoO3 oxidation state was achieved with an oxygen plasma treatment. The changes of the hole accumulation layer were monitored using in situ XPS where the binding energy of the diamond C 1s core level was correlated with electrical measurements. The valence band offsets are found to be 2.7±0.2 and 3.1±0.2 eV for Al2O3/H-terminated diamond and MoO3/diamond, respectively. The diamond sheet resistance and the hole concentration and mobility were characterized for different dielectric layer structures. Compared to the Al2O3/H-terminated diamond structure, a lower sheet resistance was achieved with MoO3 employed as surface acceptor with 2 nm A2O3 as an interface layer on H-terminated diamond. This work provides a strategy to achieve increased hole mobility of surface conductive diamond by using optimal interlayers with high electron affinity surface acceptor materials.
This research is supported by a grant from MIT-Lincoln Laboratories.
4:30 PM - EM06.13.04
Optimizing the Design of RF Transfer Doped Diamond FETs
Pankaj Shah 1 , James Weil 1 , Glen Birdwell 1 , Tony Ivanov 1
1 Sensors and Electron Devices Directorate, US Army Research Laboratory, Adelphi, Maryland, United States
Show AbstractFor RF electronics we see diamond FETs potentially displacing GaN HEMTs in applications requiring greater power due to its high thermal conductivity, high charge carrier density and larger bulk breakdown voltage. However, further optimization and understanding is needed to also make advances in speed, bandwidth, dynamic range, and efficiency as needed in today’s complex and crowded electromagnetic environment. To aid our program of fabricating and testing RF high-power diamond FETs we are using electrothermal simulations to augment our understanding of the device physics and transfer doping process.
Electrothermal simulation of the device is accomplished using Silvaco Atlas/Blaze/Giga software solving the drift-diffusion model and heat flow equations. Diamond surface polishing and techniques to hydrogenate the surface (plasma or molecular) to create the surface channel are known to make the hole conduction region of the FET nonuniform. This is considered through distributed material parameters over the diamond surface region cross section. Results indicate surface region mobility stratification from 50 cm2/V/s closest to the surface and increasing further from the surface models the device most accurately. This low and distributed mobility mimics the subsurface damage and roughness at the surface of the FET and is comparable to effective mobility measured using inhouse fabricated devices. [1] The simulations also capture the physics of transfer doping and indicate that the electron affinity difference between the transition metal oxide acceptor layer and the hydrogenated diamond controls the current in the channel. The channel current increases 2.8 times for an electron affinity difference between a transition metal oxide transfer dopant and the hydrogenated diamond surface increasing from 5.7 eV to 6.1 eV and increases 2.02 times when the difference increases from 6.1 eV to 6.5 eV. This indicates that a particular diamond surface with less than complete hydrogen coverage, [2] having less than the expected maximum negative electron affinity at the surface can still exhibit surface conduction using the proper transfer dopant.
These simulations can also help with choosing the proper acceptor transfer dopant layer crystalline phase. Processes to improve the insulating performance and obtain the large energy gap of alpha-MoO3 instead rather than other phases appears to affect the hydrogenation at the surface through possibly an oxidative dehydrogenation reaction. Results indicate that the sheet resistance of the surface conduction region with e-beam evaporated MoO3 is 5000 Ohm/Sq for amorphous and 6500 Ohm/Sq for the mixed beta/alpha phase. Also thermal evaporated MoO3 may lead to better results as indicated by a sheet resistance of 2830 Ohm/Sq perhaps due to less reactivity with the hydrogenation.
[1] P. Shah, et. al., MRS Advances, DOI: https://doi.org/10.1557/adv.2017.141
[2] F. Maier, et. al., Phys. Rev. B, vol. 64, p. 165411, 2001.
4:45 PM - EM06.13.05
Improving Surface Charge-Transfer Doping Efficiency and Robustness of Diamond with Transition-Metal Oxides
Moshe Tordjman 1 , Kamira Weinfeld 1 , Rafi Kalish 1
1 , Israel Institute of Technology (Technion), Haifa Israel
Show AbstractTransfer doping (TD) of hydrogen terminated diamond (D:H) with various materials suffers from rather low efficiency and from temperature instability. Here we show that transfer doping of hydrogen terminated diamond with selected transition-metal oxides leads to improved p-type sheet conductivity and remarkable thermal stability for only few monolayers of coverage. Surface conductivities, as determined by Hall Effect measurements as function of temperatures for first monolayers coverage yielded record total areal hole densities of up to 2.54 x1014 cm-2 at room temperature. Transfer doping robustness is also achieved with sheet conductivity values of 3x1013 cm-2 exhibiting thermal stability up to 450 °C. These enhanced conductivity efficiency and temperature robustness exceed other surface electron acceptor materials realized so far at diamond interface. X-ray photoelectron spectroscopy (XPS) measurements of the C1s core level shift as function of layer thicknesses are used to determine the respective increase in surface band bending of the accumulation layers, leading to different sub-surface two-dimensional hole gas formation efficiency for each acceptor type. This substantial difference in charge-exchange efficiency is unexpected since both surface acceptors have very close work functions values. Consequently, these results invite us to consider additional factors influencing the transfer doping mechanism.
The here reported improved surface conductivity performance and thermal stability are essential for the realization of new kinds of diamond-based surface sensitive electronic devices, which require harsh process fabrications conditions.
Symposium Organizers
Philippe Bergonzo, CEA Saclay
Timothy Grotjohn, Michigan State University
Mutsuko Hatano, Tokyo Institute of Technology
Christoph Nebel, Fraunhofer IAF
Symposium Support
Applied Diamond, Inc.
Arios Ltd.
CARAT Systems
CIVIDEC Instrumentation GmbH
Cline Innovations, LLC
DiamFab
ICDAT LTD.
Microwave Enterprises, Ltd.
Fraunhofer Center for Coatings and Diamond Technologies- Michigan State University
New Diamond Technology, LLC
Seki Diamond Systems
EM06.14: Boron Doping and Delta Structures
Session Chairs
Thursday AM, November 30, 2017
Hynes, Level 1, Room 108
8:30 AM - EM06.14.01
Investigation of Single-Crystal Diamond with Boron-Doped Delta-Layers—CVD Growth, Characterization and Electrical Measurements
Anatoly Vikharev 1 , Aleksey Gorbachev 1 , Mikhail Lobaev 1 , Dmitry Radishev 1 , Vladimir Isaev 1 , Sergey Bogdanov 1 , Mikhail Drozdov 1 , Evgeny Demidov 1 , Katherine Surovegina 1 , Vladimir Shashkin 1 , Pavel Yunin 1 , James Butler 1
1 , Institute of Applied Physics RAS, Nizhny Novgorod Russian Federation
Show AbstractCVD diamond offers significant advantages over other semiconductor materials due to its high electrical breakdown strength, high carrier mobility, high thermal diffusivity, and other properties. Diamond semiconductor devices will likely impact applications in high power, high frequency, high temperature, and/or harsh or corrosive environments. One of the strategies for enabling active electronic devices based on diamond is ‘delta doping’ with an electronically active impurity dopant.
In this paper the results on the investigation of single-crystal diamond (SCD) with boron-doped delta-layer are presented. Investigations were made on a 2.45 GHz CVD reactor designed for growth of delta layers inside SCD [1, 2]. Boron concentration in the delta layer and the doping profile was determined by SIMS method. Boron incorporation in the delta layers as a function of substrate temperature and B/C ratio in the reactant gas was determined. As the result of experiments successful producing of delta layers with thickness 1-2 nm, boron concentration (5-10) 1020 cm-3 and an abrupt interface between highly doped and undoped layers on a sub-nanometer transition layer was performed. CV measurements were performed on sample with two ‘delta layers’ and an underlying heavily doped layer. Mesa structures of diameters 25 to 400 µm were formed by lithographic masking and etching down to the heavily boron doped layer. It was found that the portion of holes outside of the delta layer sufficiently increased in samples with higher boron concentration and less thickness. Measurements of the holes mobility in various samples were made by the Van der Pau method, and the maximum hole mobility was determined to be 300 cm2/Vs. Produced doped layers are highly desirable for the development of diamond-based electronic devices.
[1] A.L. Vikharev, A.M. Gorbachev, M.A. Lobaev et. al, Phys. Status Solidi RRL, (2016) DOI 10.1002/pssr.201510453.
[2] J.E. Butler, A.L Vikharev, A.M. Gorbachev, M.A. Lobaev et al., Phys. Status Solidi RRL, (2016) DOI 10.1002/pssr.201600329
8:45 AM - EM06.14.02
Altering Mid Gap Acceptor Levels by Morphology Tuning of Boron Doped Diamonds
Sneha Choudhury 1 2 , Tristan Petit 1 , Jian Ren 1 3 , Benjamin Kiendl 4 , Fang Gao 5 , Christoph Nebel 5 , Hugues Girard 6 , Jean-Charles Arnault 6 , Evgeny Ekimov 7 , Igor Vlasov 8 , Karin Larsson 9 , Anke Krueger 4 , Emad Aziz 1 3 10
1 Institute of Methods for Material Development, Helmholtz Zentrum Berlin, Berlin Germany, 2 Institute of Chemistry, Freie Universitaet Berlin, Berlin Germany, 3 Department of Physics, Freie Universitaet Berlin, Berlin Germany, 4 Institute fuer Organische Chemie, Universitaet Wuerzburg, Wuerzburg Germany, 5 , Fraunhofer Institute for Applied Solid State Physics, Freiburg Germany, 6 CEA, LIST, Diamond Sensors Laboratory, Gif-sur-Yvette France, 7 Institute for High Pressure Physics, Russian Academy of Sciences, Moscow Russian Federation, 8 General Physics Institute, Russian Academy of Sciences, Moscow Russian Federation, 9 , Uppsala University, Uppsala Sweden, 10 School of Chemistry, Monash University, Clayton, Victoria, Australia
Show AbstractHydrogen terminated diamond is a very promising material for high energy photocatalytic reactions1 owing to its large band gap(5.5 eV) and a unique capability of generating solvated electrons due to its negative electron affinity.2 However, a major limitation to the photoexcitation process to create solvated electrons is the need for deep UV illumination. Introducing unoccupied electronic states within the band gap of diamonds by doping with boron could provide a potential pathway for photoexcitation using visible light.
Previous reports on HRTEM and EELS study of B doped polycrystalline and nanocrystalline diamonds provide insights into the local B environment.4,5,6,7 However, since these are primarily electron in-electron out techniques, they do not provide sufficient information about the existence of acceptor levels in the band gap of diamonds that are associated with boron doping. X-ray spectroscopy techniques have been shown to be sensitive to the acceptor levels arising due to boron doping.3 However, their physical origin still remains unclear.
Here we use soft X-ray absorption spectroscopy (XAS) to probe the unoccupied electronic states at the carbon K edge in different boron-doped diamond materials, ranging from single crystal and polycrystalline film to diamond foam and nanodiamonds with different sizes. XAS of carbon K edges for the different B doped diamonds were characterized using partial fluorescence yield at the BESSY II synchrotron facility. Combining these results with density functional theory calculations, here we elucidate the contribution of the environment of boron to these mid gap acceptor states that vary with the morphology of diamonds. These results could have important implications on the selection of a suitable diamond based visible-light photocatalysts.
This project has received funding from the European Union's Horizon 2020 Program under Grant Agreement no. 665085 (DIACAT).
References:
1. Zhu, D.; Zhang, L.; Ruther, R.; Hamers, R. Nature Materials 2013, 12, 836-841.
2. Takeuchi, D.; Kato, H.; Ri, G.; Yamada, T.; Vinod, P.; Hwang, D.; Nebel, C.; Okushi, H.; Yamasaki, S. Applied Physics Letters 2005, 86, 152103.
3. Zegkinoglou, I.; Cook, P.; Johnson, P.; Yang, W.; Guo, J.; Pickup, D.; González-Moreno, R.; Rogero, C.; Ruther, R.; Rigsby, M.; Ortega, J.; Hamers, R.; Himpsel, F. The Journal of Physical Chemistry C 2012, 116, 13877-13883.
4. Dubrovinskaia, N.; Wirth, R.; Wosnitza, J.; Papageorgiou, T.; Braun, H.; Miyajima, N.; Dubrovinsky, L. Proceedings of the National Academy of Sciences 2008, 105, 11619-11622.
5. Lu, Y.; Turner, S.; Verbeeck, J.; Janssens, S.; Wagner, P.; Haenen, K.; Van Tendeloo, G. Applied Physics Letters 2012, 101, 041907.
6. Turner, S.; Idrissi, H.; Sartori, A.; Korneychuck, S.; Lu, Y.; Verbeeck, J.; Schreck, M.; Van Tendeloo, G. Nanoscale 2016, 8, 2212-2218.
7. Turner, S.; Lu, Y.; Janssens, S.; Da Pieve, F.; Lamoen, D.; Verbeeck, J.; Haenen, K.; Wagner, P.; Van Tendeloo, G. Nanoscale 2012, 4, 5960.
9:00 AM - EM06.14.03
Infrared Absorption Spectroscopy of High Quality IIb-Type HPHT Diamonds Doped by Isotopically Enriched Boron
Vitaly Bormashov 1 , Sergey Pavlov 2 , Sergei Tarelkin 1 , Dmitry Prikhodko 1 , Mikhail Kuznetsov 1 , Sergey Terentiev 1 , Artem Galkin 1 , Heinz-Wilhelm Hübers 2 3 , Vladimir Blank 1
1 , TISNCM, Troitsk Russian Federation, 2 Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berline Germany, 3 Department of Physics, Humboldt-Universität , Berlin Germany
Show AbstractBoron doped diamond material can possibly be used for optoelectronics in infrared range. It requires knowledge of fundamental structure of electronic states of acceptor centers formed by substitutional boron atoms. To date, known and commonly accepted are: boron binding energy and rich and complicated spectrum of boron-mediated lines falling in the infrared (IR) wavelength range. Exact assignment of the boron-related IR transitions is still under question. The reasons are first of all different line broadening mechanisms, such as concentration, isotopic content, as well as correlation of some boron-mediated bands with strong lattice bands in diamond.
As was presented earlier high-quality boron doped diamond single crystals grown by temperature gradient method under high pressure (HPHT) have sharper boron related absorption peaks when compared with natural or CVD grown material. Here we present the results aimed to identification of structure of excited boron states by high resolution low-temperature IR absorption spectroscopy of such diamond samples. We cut (001) plates by laser from IIb-type HPHT diamond crystals. Two different boron sources were used for doping: amorphous natural boron and isotopically enriched boron oxide with at least 99% of 11B. Plates were double-side polished with wedge of ~ 1° to avoid interference. For each samples shadow masks were produced to obtain absorption from the single growth sector with uniform boron content, which was varied from 50 ppb to 1 ppm for different samples.
For diamond doped by natural boron we clearly distinguish more than 50 absorption lines. Analysis of IR spectra obtained at different lattice temperatures allows select thermally induced transitions, which correspond to population changes of spin-orbit split ground state. Reduced number of transitions in C:11B reveal on significant isotopic splitting of 0.7 meV for 10B and 11B acceptor centers. Thus, the absorption spectra can be significantly simplified by using isotopically pure samples and applying temperatures lower than 5K. It gives an opportunity for further investigation of the excited state symmetry and a hint on natural linewidth of transitions in lowest doped samples.
Acknowledgments. The work was supported by the Russian MES, project #14.580.21.0003 (RFMEFI58015X0003).
9:15 AM - EM06.14.04
Effective Boron-Doping Method Using Custom-Built MPCVD System for High Tc Superconducting Diamond
Taisuke Kageura 1 , Masakuni Hideko 1 , Ikuto Tsuyuzaki 1 , Yousuke Sasama 2 , Takahide Yamaguchi 2 , Yoshihiko Takano 2 , Hiroshi Kawarada 1 3
1 , Waseda University, Tokyo Japan, 2 , National Institute for Materials Science, Tsukuba Japan, 3 , Kagami Memorial Laboratory for Materials Science and Technology, Tokyo Japan
Show AbstractBoron-doped diamond shows superconductivity and the critical boron concentration is estimated to be around 3×1020 cm-3[1,2]. Our previous work revealed that superconducting transition temperature (Tc) of diamond increases with increasing boron concentration [B] and (111) single crystalline diamond shows higher Tc than other lattice orientation due to the anisotropic lattice strain [2]. Therefore the key to obtaining higher Tc of diamond is to establish an efficient doping technique for (111) diamond. In this study, we established an effective doping method using custom-built micro-wave plasma chemical vapour Deposition (MPCVD) apparatus, optimized the growth condition and succeeded to obtain [B]＝8×1021 cm-3 diamond with Tc(offset)=10K. Then we revealed the several properties of superconducting diamonds, including the effect of lattice distortion on superconductivity.
Our MPCVD system is based on the quartz tube MPCVD apparatus and has two unique improvements. One point is a microwave shield with water cooling jacket to limit microwave within the wave-guide boundaries and to generate high density plasma. Second point is a narrow quartz tube (diameter=31 mm) with a small inner diameter (8, 15 mm) to transport boron source gas efficiently to a diamond substrate. Superconducting diamond thin films were synthesized on HPHT Ib (111) single crystalline diamond substrate. H2+CH4+Tri-Metyl-Boron (TMB) gas mixture was used. The Boron concentration in diamonds was controlled by gas ratio ([TMB]/ [CH4], [CH4]/ [Total gas]), deposition temperature and pressure. We revealed that Tc increases with increasing gas pressure and saturate around 110 Torr with Tc=10K. The upper critical field of diamond with Tc=10K was estimated to be 15-20T. The boron concentrations of the diamond with Tc=10K was estimated to be 8×1021 cm-3 by secondary ion mass spectroscopy (SIMS) therefore the doping efficiency was calculated to be about 440%. Generally the boron-doping efficiency decreases with increasing boron concentration in diamond and that of conventional methods were below 100%. Our high doping efficiency indicates that our improvement in MPCVD apparatus is effective for not only heavy boron doping but also high efficiency of doping. The lattice distortion of diamond with [B]=8×1021 cm-3 was measured by high resolution X-ray diffractometer and the lattice mismatch was 0.6%. According to the Vegard’ law, almost all boron in the sample exists in substitutional site.
We demonstrated one effective boron-doping method using custom-built MPCVD system. We will show the details of our system and the other results on that day.
This work was supported by a Grant-in-Aid for Fundamental Research S (26220903, JSPS).
References
[1] E. A. Ekimov et al., Nature. 428 (2004) 542.
[2] A.Kawano, H.Kawarada et al., Phys. Rev. B 82 (2010) 085318.
9:30 AM - EM06.14.05
Fano Effects in Boron Doped Diamond
V. Mortet 1 2 , Z. Zivcová 3 , O. Frank 3 , Andrew Taylor 1 , Pavel Hubik 1 , M. Davydova 1 , L. Kavan 3
1 , Institute of Physics of CAS, v.v.i., Prague Czechia, 2 Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno Czechia, 3 , J. Heyrovsky Institute of Physical Chemistry of CAS, v.v.i., Prague Czechia
Show AbstractRaman spectrum of heavily boron doped diamond is only partially understood. For instance, the assignment of the broad band located at c.a. 500 cm-1 to a local vibration mode of boron pairs [1] could not be unambiguously resolved by isotopic substitution studies [2]. Further, the assignment of the band located at c.a. 1200 cm-1 to the maximum of phonon density of state (PDOS) is not fully satisfactory due to the discrepancy between the position of the measured and the theoretical PDOS-associated peaks.
In this work, we analyse Raman spectra of heavily boron doped epitaxial diamond layers. The interaction of electronic Raman scattering with diamond’s zone-centre Raman line, i.e. the Fano effect, is analysed as a function of boron concentration. This analysis indicates that the phonon confinement effect is due to the high density of boron. Based on this result and the expected appearance of PDOS maxima with the electronic Raman scattering as previously suggested in ref. [4].
Acknowledgements: This work was supported by the Grant Agency of the Czech Republic (contract No. 13-31783S) and the J.E. Purkyne fellowship awarded to V. Mortet by Academy of Sciences of the Czech Republic.
[1] M. Bernard et al., Diamond Relat. Mater. 13 (2004) 896
[2] V. A. Sidorov et al., Diamond Relat. Mater. 19 (2010) 351
[3] R. T. Harley et al. Phys. Rev. Lett. 23 (1969) 922
[4] E. Bustarret et al., phys. stat. sol. (a). 199 (2003) 9
EM06.15: Biosensing with Diamond Optical Centers
Session Chairs
Thursday PM, November 30, 2017
Hynes, Level 1, Room 108
10:15 AM - EM06.15.01
Protein Analysis by Label Free Evanescent Mid-IR Diamond Waveguide Spectroscopy
Mikael Karlsson 1 2 , Fredrik Nikolajeff 1 2 , Lars Österlund 1 2 , Per Ola Andersson 1 2 3 , Pierre Piron 1 , Ernesto Vargas Catalan 1 , Joakim Bergström 4
1 Engineering Sciences, Uppsala University, Uppsala Sweden, 2 , Molecular Fingerprint Sweden AB, Uppsala Sweden, 3 CBRN Defence and Security, FOI Swedish Defence Research Agency, Umeå Sweden, 4 Public Health and Caring Sciences, Uppsala University, Uppsala Sweden
Show AbstractWe have during the last years been working on the microfabrication of diamond waveguides. The diamond waveguides together with a broadly tunable laser quantum cascade laser (QCL), emitting from 5.5 µm up to 11 µm, are the two key elements in our newly developed label free biosensor based on vibrational spectroscopy. When coupling IR-light through the waveguide an evanescent wave will be created at the waveguide surface which will interact with the analyte. Because of the reduced thickness when using waveguides, in combination with using QCL lasers as a light source, an ultra sensitive sensor is expected (compared to ATR-IR spectroscopy). Moreover, our waveguide can be functionalized which can be used to bind antibodies to the sensor surface.
The waveguides are fabricated by standard lithographic techniques followed by inductively coupled plasma etching of diamond. We start with a 10x10 mm2 substrates consisting of 500 µm Si, 2 µm SiO2 (cladding layer) and a polished polycrystalline diamond film on top. Different dimensions of diamond waveguides have successfully been fabricated; thicknesses from 5-15 µm, widths of 10-500 µm, all with a length of 8 mm. When plasma etching diamond most often pure oxygen chemistry is used, but here we also try to add small amounts of SF6 which reduce re-deposition of the etch mask, and thus give smother sidewalls of the waveguides. Both free hanging diamond waveguides (Si is removed from the back side of the waveguides), strip- and rib waveguides are demonstrated. Focused ion beam etching is used to polish the in- and out coupling area of the waveguides, this to get as much light as possible through the waveguides. Simulations of the light propagation in the different types of waveguides are also presented.
The optical setup of the biosensor is presented, consisting of a broadly tunable QCL, IR-optics (lenses etc.) for coupling the light into the diamond waveguide, a so called Pyrocam to visualize the IR-beam profile when exiting the diamond waveguide, and a sensitive MCT-detector.
We will present our first measurements on different types of analytes (e.g. isopropanol) at low concentrations (ng) to demonstrate the sensitivity of the sensor.
We are working on analyzing different forms of the protein alpha-synuclein, which is relevant in understanding the mechanism behind Parkinson’s disease. Recently, we used ATR-IR spectroscopy to analyze the secondary structure of different alpha-synuclein aggregates. Interestingly, it seems to be possible to see the difference in the IR-spectra between the native state and the neurotoxic misfolded state of the protein. Our sensitive diamond waveguide biosensor will be used to analyze the secondary structure of alpha-synuclein at biologically relevant concentrations. Future work includes the functionalization of the diamond waveguide sensor surface to be able to fish out alpha-synuclein from cerebrospinal fluid, with the ultimate goal to detect Parkinson’s disease at an early stage.
10:30 AM - *EM06.15.02
Cooperatively-Enhanced Atomic Dipole Forces in Optically Trapped Nanodiamonds Containing NV Centres, in Liquid
C Bradac 1 , Mathieu Juan 2 , Benjamin Besga 2 , Mattias Johnsson 2 , Matthew van Breugel 2 , Rochelle Martin 2 , Ben Baragiola 2 , Gavin Brennen 2 , Gabriel Molina-Terriza 2 , Thomas Volz 2
1 , University of Technology Sydney, Sydney, New South Wales, Australia, 2 , Macquarie University, Sydney, New South Wales, Australia
Show AbstractNanodiamonds (NDs) containing colour centres are remarkable objects which find applications in a wide range of disciplines, from quantum information technology to quantum metrology and bio-sensing. In life sciences, fluorescent nanodiamonds are implemented as non-toxic biomarkers for biomedical imaging1 and drug delivery.2,3 In recent experiments they have been tracked within living cells,4 and optically manipulated in liquid,5 yet their manipulation in a 3D biological environment remains beyond reach. Classical optical tweezers cannot trap particles much smaller than ~100 nm. We propose a new approach that stems from cold-atom trapping experiments6 and addresses this limitation.
We exploit artificial atoms – colour NV centres within the nanodiamond host (~103 NVs/particle) – to enhance the trapping of the whole crystal via near-resonant forces acting on them. While holding the nanodiamond (~100 nm) at the focus of classical optical tweezers in liquid,7 we employ a second near-resonant laser beam, slightly detuned from the dipole transition of the target colour centres.
We measure a change in trap stiffness of ~10%, which is the signature of atomic dipole forces.8 Most interestingly, we show that our findings can only be ascribed to the existence of collective effects – ‘superradiance’ (SR) – between colour centres, which has never been reported before at room temperature for a solid-state system archetype of that originally proposed by Dicke in his seminal paper on superradiance.9
While the effect of the resonant trapping is limited for NV centers in NDs, we project an increase of at least an order of magnitude for other diamond colour centres, e.g. silicon-vacancy centres. We foresee the ability to trap nanoparticles with sizes (~tens of nm) and forces (~hundreds of pN) currently unattainable with conventional optical tweezers,10 towards dynamic, single-molecule experiments. Moreover and most importantly, our findings on superradiance offer the prospect of quantum engineering a tailored, room-temperature SR system for applications in quantum metrology11 and light harvesting.12
References
[1] Schrand, et al., Critical Rev. in Solid State and Mat. Sci., 34(1–2), 18–74, 2009; [2] Purtov, K.V., et al., Nanoscale Research Letters, 5(3), 631–636, 2010; [3] Alhaddad, A., et al., Small, 7(21), 3087¬–3095, 2011; [4] McGuinness, L.P., et al., Nature Nanotech, 6, 358–363, 2011; [5] Horowitz, V.R., et al., PNAS, 109(34), 13493–13497, 2012; [6] Grimm, R., M. Weidemuller, and Y.B. Ovchinnikov, arXiv:physics/9902072, 1999; [7] Ashkin, A., et al., Optics Letters, 11(5), 288–290, 1986; [8] Juan, M. L., et al. Nature Physics. 3940, 2016; [9] Dicke, R. H., Phys. Rev., 93, 99–110, 1954; [10] Jannasch, A., et al., Nat Photon, 6(7), 469–473, 2012; [11] Zhang, Z. & Duan, L. M., NJP 16, 103037 (2014); [12] Higgins, K. D. B., et al., Nature Comm 5 1–7, (2014).
11:00 AM - EM06.15.03
Charge Stability and Coherenece Property of Shallow Nitrogen Vacancy Center in Nitrogen Terminated Diamond for DNA Detection
Sora Kawai 1 , Hayate Yamano 1 , Kanami Kato 1 , Jorge Buendia 1 , Taisuke Kageura 1 , Masafumi Inaba 1 5 , Ryosuke Fukuda 1 , Takuma Okada 1 , Moriyoshi Haruyama 2 3 , Takashi Tanii 1 , Shinobu Onoda 2 , Wataru Kada 3 , Osamu Hanaizumi 3 , Tokuyuki Teraji 4 , Shozo Kono 1 6 , Hiroshi Kawarada 1 6
1 , Waseda University, Shinjuku, Tokyo, Japan, 5 , Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya, Aichi, Japan, 2 , National institute for Quantum and Radiological Science and Technology, Takasaki, Gunma, Japan, 3 , Gunma University, Kiryu, Gunma, Japan, 4 , National Institute for Materials Science, Tsukuba, Ibaraki, Japan, 6 , Kgami Memorial Research Institute for Materials Science and Technology, Waseda University, Shinjuku, Tokyo, Japan
Show AbstractNegatively charged Nitrogen Vacancy (NV) center in diamond shows excellent properties which are valuable for nanoscale NMR[1]. It is desirable that NV center is created as shallow as possible for detecting nuclear spins on diamond substrate. However, such shallow NV centers can be easily affected by surface and external environment and thus show instability of negatively charged state as compared to these in bulk. Therefore, it is necessary for detection of nuclear spin to improve the charge stability of shallow NV center. Shallow NV centers in oxygen terminated were well-studied [2]. It is reported that nitrogen terminated diamond shows positive electron affinity (PEA) [3] which is suitable for negatively charged state of shallow NV center as well as oxygen terminated diamond. Furthermore, it is possible to directly fix biomolecule to surface by using NH2 functional group with amide bond [4]. However, there are few reports to investigate properties of NV center in nitrogen terminated diamond. Here, we investigated the effect of nitrogen radical exposure which induces nitrogen termination on shallow NV centers.
Shallow NV centers were created in 12C enriched (001) diamond [5] by low energy (2.5 keV) nitrogen ion implantation and subsequent annealing. Nitrogen ion was implanted with resist mask which has arrayed nanoholes. We also made address with patterned signs. Then, the diamond substrate was cleaned by hot acid mixture treatment. In addition, nitrogen radical exposure using RF radical beam source with N2+H2 (4 %) was carried out as a nitridation process. We evaluated properties of shallow NV centers by Rabi oscillations and Hahn echo measurement before and after nitridation. Before nitridation, charge state of shallow NV centers was estimated to be unstable from average Rabi oscillation contrast. On the other hand, average contrast was improved by more than 1.5 times after nitridation. Our group reported that nitrogen coverage estimated by X-ray Photoelectron Spectroscopy was 0.9 ML [6]. Therefore, it is suggested that the diamond surface after our nitridation shows PEA and contributed to stabilize negatively charged state of shallow NV centers. Coherence time T2 measured by Hahn echo pulse sequence was ranged from 1 to 30 µs. Further investigation of coherence property and influence of DNA immobilization on T2 by dynamical decoupling is necessary.
[1] S. J. DeVience, R. L. Walsworth, et al., Nat. Nanotech. 10, 129 (2015).
[2] H. Yamano, H. Kawarada, et al., Jpn. J. Appl. Phys. 56, 04CK08 (2017).
[3] A. Stacy, S. Prawer, et al., Adv. Mater. Interfaces 2, 1500079 (2015).
[4] H. Kawarada and A. R. Ruslinda, Phys. Status Solidi A 208, 2005 (2011).
[5] T. Teraji, J. Appl. Phys. 118, 115304 (2015).
[6] T. Kageura, H. Kawarada, et al., Appl. Phys. Express 10, 055503 (2017).
Acknowledgements
We thank Dr. Liam P. McGuinness and Prof. Fedor Jelezko for their help with setting up the CFM.
11:15 AM - EM06.15.04
Improving the Sensitivity of a Biocompatible Nitrogen-Vacancy Center Ensemble Magnetometer
Claire McLellan 1 , Tim Eichhorn 1 , Gabriel Zihlmann 1 , David Awschalom 2 , Ania Bleszynski Jayich 1
1 , University of California, Santa Barbara, Santa Barbara, California, United States, 2 , The University of Chicago, Chicago, Illinois, United States
Show AbstractMagnetic sensing of biological samples provides a non-invasive method to study phenomena ranging from neuron action potentials to biogenic magnetite. In the Jayich lab, we have developed a biocompatible imaging magnetometer based on nitrogen-vacancy (NV) center ensembles in diamond. Using the wide-field imaging capabilities of our magnetometer, we can tune our spatial resolution and magnetic sensitivity to the needs of the magnetic system. A challenging biological signal to detect is the magnetic field produced by a neuron action potential because the field is small (~nanoTesla at a distance of 1 micron from the axon) and persists for only a few milliseconds. I will be discussing our work towards understanding and improving the sensitivity our magnetic imaging system with the ultimate goal of noninvasively imaging neuronal action potentials.
Because the NV center is a quantum sensor, its sensitivity improves with increased quantum coherence time. A limit to NV coherence in high-density ensembles is the presence of substitutional nitrogen atoms (P1 centers), paramagnetic spins in the diamond lattice. By combining optically detected magnetic resonance (ODMR) with double electron-electron resonance (DEER) techniques, we study the effect of paramagnetic spins on the coherence of NV center ensembles. This technique allows us to access small spin numbers usually inaccessible by standard electron paramagnetic resonance (EPR) techniques. Informed by these characterizations, we tune our growth parameters to optimize the nitrogen incorporation during diamond plasma enhanced chemical vapor deposition (PECVD) growth and hence improve our magnetometer’s sensitivity. Finally, I will present recent progress using our diamond magnetometer to probe biological samples.
11:30 AM - EM06.15.05
Towards Energy Transfer-Based Sensing and Imaging with Color Centers in Single-Crystal Diamond
Richard Nelz 1 , Alexander Meyer 1 , Michel Challier 1 , Selda Sonusen 1 , Ettore Bernardi 1 , Elke Neu 1
1 , Saarland University, Saarbruecken Germany
Show AbstractIndividual nitrogen vacancy (NV) color centers in diamond are bright, photo-stable dipole emitters. Consequently, they represent optimal candidates for novel scanning near field microscopy techniques [1]. Here, NV centers form one member of a Förster Resonance Energy Transfer (FRET) pair. Due to their broadband emission (> 100 nm), NVs are versatile donors for FRET to systems absorbing in the near infrared spectral range. Highly-promising applications include, e.g., nanoscale imaging of fluorescent molecules or nanomaterials like graphene [1].
For optimal stability and fluorescence collection, NV centers in single crystal nanostructures are highly-desirable. However, so far FRET has not been realized using such NV centers. Critical parameters are their quantum efficiency (QE) and the NV-to-sample distance. While the quantum efficiency is high in single-crystal diamond, strong variations are found in nanodiamonds [2] and no investigations of the QE in single-crystal nanostructures are reported. We here address this issue.
We fabricate cylindrical nanostructures (200 nm diameter, 150 nm height) with shallowly-implanted (< 10 nm) NV centers in single-crystalline diamond. We thus mimic the situation attainable with scanning probe devices sculpted out of single-crystal diamond [3]. Fluorescence lifetime imaging of individual shallow NVs in these nanostructures reveals lifetimes between 18 and 25 ns, indicating prolonged lifetimes compared to bulk (12 ns). We use a home-built combination of an atomic-force and a confocal fluorescence microscope, addressing single NV centers. Simultaneously, we change the local density of states by scanning a metallic tip above the NV; potentially enabling to determine the quantum efficiency.
In addition to these measurements, we investigate the charging and de-charging of our NV centers. Following recent work, we use excitation with yellow laser light (594 nm) to selectively excite the negative NV charge state. We discuss possible connections between charging and de-charging dynamics and quantum efficiency. We discuss the influence of surface treatments, annealing and nanofabrication on charge state stability and quantum efficiency. Determining the NV’s quantum efficiency allows to select optimal candidates for scanning near field imaging. Moreover, we aim to further exploit the NV charge state as a nanoscale sensing resource.
[1] Sekatsitkii et al., Faraday Discuss. 184 51-69 (2015); Tisler et al., Nano Lett. 13 3152-3156 (2013)
[2] Mohtashami and Koenderink, New J. Phys. 15 043017 (2013); Radko et al., Opt. Express 24 27715-27725 (2016)
[3] Appel et al., Review of Scientific Instruments 87 063703 (2016)
11:45 AM - EM06.15.06
Detection and Localization of Luminescent Nanodiamonds in Cellular Environment Using Raman Imaging
Michal Gulka 1 2 7 , Bela Varga 3 4 , Hamideh Salehi 5 , Elodie Middendorp 5 , Thierry Cloitre 3 , Frederic Cuisinier 5 , Petr Cigler 6 , Milos Nesladek 7 , Csilla Gergely 3
1 Faculty of Biomedical Engineering, Czech Technical University, Kladno Czechia, 2 , Institute of Physics, Prague Czechia, 7 , IMOMEC Division, imec, Institute for Materials Research, Hasselt Belgium, 3 , Laboratoire Charles Coulomb (L2C), Montpellier France, 4 , Institute of Biophysics, Szeged Hungary, 5 , Bio-engineering Nanoscience Laboratory, Montpellier France, 6 , Institute of Organic Chemistry and Biochemistry AS CR, Prague Czechia
Show AbstractLuminescent nanodiamonds (ND) are attractive tools for nanoscale biologic cellular imaging allowing both photoluminescence (PL) and magnetic resonance imaging [1]. Recent technological developments enable to fabricate bright NDs with high content of nitrogen-vacancy (NV) centres [2] that are anticipated to serve as a cell probes. In this work we present novel method of NDs detection in cellular environment. We demonstrate simultaneous visualization of NDs and of the non-labeled nucleus of living cells based on Raman and PL detection as a new tool for the localization of internalized nanoparticles.
To this end, NDs of size ranging from ultra-small particles ~ 5 nm to 60 nm were used, prepared from Ib synthetic diamond. Particles were electron irradiated, annealed and plasma oxidized to create NV centers [3]. Cells used for this experiment were breast cancer (MCF7). Successful internalization of NDs and their localization in cells is determined using a TEM. Whilst standard Raman imaging methods of NDs make use of the sp3 diamond Raman signal, which limits their use to 100 nm size particles or bigger [4], here we employ Raman imaging in a novel way to detect small near-IR cellular probe. Specifically, the Raman signal from the cellular environment is spectrally processed using K-mean cluster analysis of 2D map. By mapping the intensity of the lipid contribution to the C-H Raman peak, we are able to visualize the cell nucleus clearly on non-fixed cells. This information is combined with PL detection of small (~ 5 nm) particles to visualize the position of NDs and distinguish between the internalized and non-internalized particles. Merging of these two images obtained simultaneously allows to obtain a spatially precise ND position and to determine its closer environment.
[1] L. Moore, M. Nesladek et al., Nanoscale (2014)
[2] J. Havlik, M. Gulka, M. Nesladek et al., Nanoscale (2013)
[3] J. Stursa, M. Gulka, M. Nesladek et al., Carbon (2016)
[4] C.-Y. Cheng et al., Applied Physics Letter (2007)
ACKNOWLEDGMENTS:
Czech Science Foundation project GA16-16336S
EM06.16: N-Type Doping
Session Chairs
Thursday PM, November 30, 2017
Hynes, Level 1, Room 108
1:45 PM - *EM06.16.01
Improving the Crystalline and Electronic Quality of n-Type Diamond
Shannon Nicley 1 , Paulius Pobedinskas 1 , Rozita Rouzbahani 1 , Oluwasayo Loto 2 , Patrik Scajev 3 , Kestutis Jarasiunas 3 , Julien Pernot 2 , Ken Haenen 1
1 , Hasselt University & IMOMEC, IMEC vzw, Diepenbeek Belgium, 2 Institut Néel, Université Grenoble Alpes, Grenoble France, 3 Institute of Applied Research, Vilnius University, Vilnius Lithuania
Show AbstractThe improvement of the crystalline quality for the reliable deposition of electronic grade n-type diamond is necessary for the commercial realisation of this exceptional semiconductor material. Achieving controllable levels of the n-type dopant phosphorus (P) has been a challenge, and is an area of significant current interest1-3. The substrate temperature during doped diamond growth is important, and has been shown to affect the surface morphology and dopant concentrations for boron doped single crystal diamond (SCD)4.
In this work, recent studies on the optimisation of P-doped SCD film growth will be presented. Diamond was deposited homoepitaxially by microwave plasma enhanced chemical vapour deposition with varying ratios of phosphine and methane in hydrogen (H), on (111) and (100) oriented substrates. The nucleation of unepitaxial crystallites on P-doped diamond surfaces was shown to be supressed at higher growth temperatures. H-plasma etching at substrate temperatures from 800–950 °C showed that smoother surfaces are obtained at higher etching temperatures. P-doped films grown on (100) substrates after H-plasma pre-treatment showed fewer surface defects than on untreated substrates.
Thick samples with varying P/C in the plasma feedgas were grown in a series of 24 h deposition experiments at 1000 °C for characterisation by photocurrent, carrier lifetime, Hall effect, cathodoluminescence (CL), and Fourier transformed infrared (FTIR) spectroscopy. FTIR and Hall effect results confirm the P-incorporation at the high growth temperature studied (1000 °C). FTIR spectra further show that the absorption related to the 1S → 2P+/- electronic transition of the bound electron at 562 meV varies with the P/C ratio. P is detected even in an unintentionally doped sample, confirming a reactor memory effect for P-doping. CL mapping on a P-doped diamond grown on a multisectorial plate with varying nitrogen substrate concentration was compared to carrier lifetime measurements, showing a strong correlation between the electronic and crystalline quality of the films. The conclusions drawn from these results will be summarized to give strategies for achieving the growth of high quality n-type single crystal diamond.
This work was performed within the H2020 Research and Innovation Action Project "GreenDiamond" (www.greendiamond-project.eu) under grant agreement N°640947.
References
1. R. Ohtani, T. Yamamoto, S.D. Janssens, S. Yamasaki, S. Koizumi. Appl. Phys. Lett. 105, (2014) 232106
2. H. Kato; M. Ogura; T. Makino, D. Takeuchi, S. Yamasaki. Appl. Phys. Lett. 109, (2016) 142102
3. T. A. Grotjohn, D.T. Tran, M.K. Yaran, S. Nicley Demlow, T. Schuelke, Diamond Relat. Mater. 44, (2014) 129
4. S. Nicley Demlow, R. Rechenberg, T.A. Grotjohn. Diamond Relat. Mater. 49, (2014) 19
2:15 PM - EM06.16.02
Field Electron Emission Enhancement of Nanocrystalline Diamond Films by Lithium-Ion Implantation and Annealing
Sankaran K. J. 1 2 , K. Srinivasu 3 , C. J. Yeh 3 , Paulius Pobedinskas 1 2 , Matthias Schreck 4 , I-Nan Lin 5 , Ken Haenen 1 2
1 , Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 2 , IMOMEC, imec vzw, Diepenbeek Belgium, 3 Department of Engineering and System Science, National Tsing Hua University, Hsinchu Taiwan, 4 Institute of Physics, University of Augsburg, Augsburg Germany, 5 Department of Physics, Tamkang University, Tamsui Taiwan
Show AbstractNanocrystalline diamond (NCD) films are investigated systematically for their application as field electron emitters owing to their negative electron affinity and low effective work function. While the physical properties of these films depend on the intrinsic structure of the materials, their electrical and optical properties are more closely related to the microstructure of the films. Therefore, the ability to control the microstructure and surface morphology of NCD film could tailor this material for variety of applications such as hard coatings, optical windows, micro-electro-mechanical systems and electron emitters. The decrease in diamond grain size increases the proportion of grain boundaries, which contain non-diamond carbon phases such as amorphous carbon (a-C) or trans-polyacetylene phases. These non-diamond carbon phases act as conducting channels, facilitating easy tunneling of electrons through a ‘grain boundary conduction emission’ mechanism and thus improve the field electron emission (FEE) characteristics of NCD films.
Ion implantation is a possible way to alter the electrical properties of materials via controlled doping with a wide variety of dopant species. By proper selection of the implantation energy and dose, the sp2/sp3 ratio of diamond and related carbon materials can be tailored. The sp2-bonded carbon induced during ion implantation and post-annealing treatments of NCD films is the conductivity promoter, which enables the electrons to move freely inside the films. In the present study, the effect of lithium ion implantation and post-annealing processes on the electrical conductivity and FEE properties of undoped and nitrogen doped NCD films was investigated. A high dose Li ion implantation (1014 ions/cm2) induced the formation of electron trap centers inside the diamond grains as well as a-C in grain boundaries for both NCD films. Post-annealing at 1000°C healed the defects, eliminated the electron trap centers and converted the a-C into nanographitic phases. Micro-Raman spectroscopic, X-ray photoelectron spectroscopic and transmission electron microscopic examinations indicated that there presence of abundant nanographitic phases in the grain boundaries of nitrogen doped NCD films as compared with those in undoped NCD films. The nanographitic phases formed an interconnected path for efficient electron transport and thus improved the electrical conductivity and FEE properties of nitrogen doped NCD films more profoundly, compared with those of undoped NCD films. Such a phenomenon can be attributed to the different granular structures of these two films. The nitrogen doped NCD films contain nano-sized diamond granular structure with abundant grain boundaries, which are of considerable thickness, whereas undoped NCD films contain large-grain microstructure with fewer grain boundaries, which are of negligible thickness.
K. J. Sankaran and P. Pobedinskas are Postdoctoral Fellows of the Research Foundation-Flanders (FWO).
2:30 PM - EM06.16.03
Surface States on Doped Single Crystal Diamond
Franz Koeck 1 , Robert Nemanich 1
1 , Arizona State University, Tempe, Arizona, United States
Show AbstractSolid-state and vacuum diamond electronics can exploit unique properties of diamond surfaces utilized in electrodes for electron emission and energy conversion applications as well as solid-state vertical and lateral devices. Devices requiring n-type diamond can be realized by doping with phosphorus (P) and nitrogen (N) which establishes donor levels at 0.6eV and 1.7eV, respectively. For a hydrogen passivated doped diamond surface its work function can be defined through contributions from the donor level, the electron affinity and the amount of band bending. This research focuses on the correlation between band bending, donor concentration ([N], [P]) and surface state density. We present detailed results from hydrogenated N-doped (100) and (111) oriented diamond surfaces and hydrogenated homoepitaxial P-doped diamond prepared on (100) and (111) oriented substrates. Hydrogen passivated, P-doped diamond films were epitaxially grown on (100) and (111) oriented HPHT Ib substrates by plasma-enhanced CVD. Characterization included thermionic electron emission in UHV ambient to determine the work function of the doped NEA surface and secondary ion mass spectroscopy (SIMS) to establish the doping concentration.
For P-doped films grown on the (100) surface SIMS measurements communicated a phosphorus incorporation of [P] ~1017 cm-3 and a low work function of 0.67 eV that was deduced from a data fit to the Richardson-Dushman formalism. An increase in the phosphorus concentration shifted the work function to 0.84 eV which was attributed to increased upward band bending. P-doped films with [P] ~4x1018 cm-3 and [P] ~3x1019 cm-3 were grown on (111) substrates and displayed a work function of 1.45eV and 2.43 eV, respectively, indicating more prominent upward band bending. Similarly, N-doped (111) diamond with [N] ~1.7x1019 cm-3 and N-doped (100) diamond with [N] ~3.3x1019 cm-3 established work functions of 2.39eV and 2.88eV, respectively, attributed to increased upward band bending. Elsewhere, work function measurements by photo-emission spectroscopy of P-doped (111) and N-doped (100) diamond communicated 1.45eV and 3.3eV for [P] 2~5x1019 cm-3 and [N] ~1x1020 cm-3 , respectively. [1, 2]
From the observed change in the work function for P and N-doped diamond a relation emerges that indicates a correlation between doping concentration and occupied surface state density which increased from ~1011 cm-2 to ~1013 cm-2 for low and higher doped films, respectively. We will elaborate on the role of the donor impurity and its relation to the surface states for single crystal diamond.
This research is supported by the Office of Naval Research through grant # N00014-10-1-0540.
[1] L. Diederich et al., Surface Science 418 (1998) 219–239
[2] T. Yamada et al., J. Phys. D: Appl. Phys. 49 (2016) 045102
2:45 PM - EM06.16.04
Space-Charge Outside an Intensely Donor-Doped Diamond
Johan Prins 1 2
1 , Academy for Physics Reality, Johannesburg South Africa, 2 Innovation, Zero Resistance (Pty) Ltd., Johannesburg, Gauteng, South Africa
Show AbstractOxygen-ions have been injected to extremely high doses into insulating diamond-surfaces, using a low acceleration-voltage, so that a high-density of donors forms below and near to each of these surfaces. It is found that electrons accumulate as a space-charge outside such a diamond-surface. A thin layer of ionised donors and this space-charge constitute a dipole across the surface.
Metal probes have been used as electric-contacts to inject currents through these space-charge layers. These currents manifest even when the probes are substantially (up to distances of 80 μm) above the diamond's surface.
Using an electrometer with high accuracy, the resistance for different distances between the metal-probes is found to be zero. Such a space-charge could thus be a superconductor at room temperature.
It is argued in the mainstream literature that on both sides of a dipole layer, which forms across an interface between an n-type semiconductor and a p-type semiconductor, the Fermi-levels must always have the same electronic-energy. When the Fermi-levels are at the same electronic-energy, there cannot be an electric-field within the dipole which causes diode action.
In the mainstream literature it is illogically claimed that diode action does occur when the Fermi-levels have the same energy. Diode action is, however, only obtained when the Fermi-levels are not at the same energy, so that a residual electric-field remains within the dipole.
During the time that such an n-p dipole is forming, two insulating layers form on opposite sides of the interface: One positively-charged and the other negatively-charged. The layers keep on increasing in width for as long as charge-carriers can tunnel within them.
When the insulating layers become too large for tunneling to occur, the dipole layer cannot grow further by means of tunneling; so that the electric-field within the dipole is not cancelled by the dipole's polarisation field. If tunnelling, during its formation, proceeds until the Fermi-levels have the same energy, subsequent, injected charge-carriers, from a battery, will be able to tunnel within these layers without being accelerated through them: The dipole is now able to adjust in order to cancel the battery's applied electric-field by a polarisation-field.
The dipole which is generated across a diamond surface to the vacuum, acts in a similar manner when the Fermi-level in the diamond has the same energy as the vacuum-level outside. Charge-carriers can then tunnel through the insulating layer below the diamond's surface into the external space-charge. In this case the dipole still cancels the applied electric-field within the space-charge. Thus, an injected electric-current will flow through the space-charge without an electric-field driving this current: When this happens, the space-charge must be a superconductor at room temperature.
3:00 PM - EM06.16
Concluding Remarks and EM06 Student Prize
Show Abstract