Symposium Organizers
Oliver A. Williams Cardiff University
Richard B. Jackman University College London
Philippe Bergonzo CEA-LIST
Greg N. Swain Michigan State University
Kian Ping Loh National University Singapore
N1: Plenary
Session Chairs
Monday PM, November 28, 2011
Room 306 (Hynes)
9:30 AM - **N1.1
Recent Progress in Diamond Raman Lasers.
Richard Mildren 1
1 , MQ Photonics Research Centre, Macquarie University, New South Wales, Australia
Show AbstractDiamond’s relatively low mass elemental mass, strong bonding and highly symmetric lattice provide a host of attractive and outstanding properties including large Raman scattering cross-section, high thermal conductivity, wide transparency range and lattice stability to name a few. Interest in exploiting these properties for optical devices has increased recently in parallel with improvements in the quality of synthetic material grown by chemical vapor deposition. Diamond lasers, which use the phenomenon of stimulated Raman scattering to provide optical gain, is one area in the emergent fields of diamond photonics and optical engineering that has excellent prospects for addressing important challenges in laser source development. In this paper, the recent progress in diamond Raman lasers others will be reviewed. The talk will highlight areas in which diamond holds promise for enhancing laser performance beyond that easily achieved by other means and for addressing important applications.
10:00 AM - **N1.2
Surface Engineering of Graphene.
Andrew Wee 1 , Wei Chen 2 1
1 Physics, National University of Singapore, Singapore, 0, Singapore, 2 Chemistry, National University of Singapore, Singapore Singapore
Show AbstractA major challenge in graphene-based devices is opening the energy band gap and doping. Molecular functionalization of graphene is one approach to modifying its electronic properties. Surface transfer doping by surface modification with appropriate molecular donors or acceptors represents a simple and effective method to non-destructively dope graphene. Surface transfer doping relies on charge separation at interfaces, and represents a valuable tool for the controlled and non-destructive doping of 2D materials, since traditional dopant implantation methods are not suitable. Molecular self-assembly of bimolecular systems on graphene is demonstrated, and represents a controlled method of surface engineering the properties of graphene. The doping of epitaxial graphene using oxide thin films is also presented. The hole doping effect of graphene modified by MoO3 thin film is confirmed by electrical transport measurements on prototype graphene devices.
10:30 AM - **N1.3
Charge State Manipulation of Single Qubits in Diamond.
Moritz Hauf 1 , Bernhard Grotz 2 , Boris Naydenov 2 , Markus Dankerl 1 , Sebastien Pezzagna 3 , Jan Meijer 3 , Fedor Jelezko 4 , Jörg Wrachtrup 2 , Martin Stutzmann 1 , Friedemann Reinhard 2 , Jose Garrido 1
1 Walter Schottky Institut, Technische Universität München, Garching Germany, 2 Third Institute of Physics, Stuttgart University, Stuttgart Germany, 3 RUBION, Ruhr-Universität Bochum, Bochum Germany, 4 Institute of Quantum Optics, Ulm University, Ulm Germany
Show AbstractNitrogen-vacancy defects (NV) in the diamond lattice have been extensively studied in the past for several reasons. NV centers can act as single photon emitters in the visible range with absolute photo-stability. They have found applications in novel fields like quantum computation [1] and single spin magnetometry. In this context, it is of great interest to understand the effect of diamond surface termination and gain control over the charge state of NV centers in diamond.In ensemble experiments with shallow implanted defects we have shown that by changing the diamond surface termination from oxygen to hydrogen, the fluorescence of the negatively charged NV (NV-) can be suppressed. This effect depends on the implantation energy and dose used for the creation of NV-centers in diamond by low-energy nitrogen implantation [2]. We attribute this behavior to the band bending which occurs at hydrogen-terminated diamond surfaces according to the transfer-doping model. A two-dimensional hole gas is formed at the diamond surface, converting the NV- to either neutral (NV0) or even positively charged NV-centers (NV+). Recently, we have shown that electrostatic control of the charge state of single NV centers can be achieved by using H-terminated surface-conductive diamond devices and an electrolyte gate electrode. Similar to diamond solution-gated field effect transistors [3], the electrolytic gate electrode provides a precise control over the Fermi level position at the diamond surface. In areas of high nitrogen implantation density, this allows a reversible switching of NV centers from NV- to NV0, whereas in areas of low implantation density single centers could be switched from NV0 into a state which shows now fluorescence, most likely NV+. We have performed self-consistent numerical simulations which can reproduce the surface band bending and the concurrent disappearance of the NV--fluorescence for hydrogen-terminated diamond surfaces in contact with an electrolyte. Furthermore, we can simulate the control of the charge state with an external electrolytic gate for the charge transfer levels NV0/- as well as NV+/0.[1]P. Neumann et al., Nat. Phys. 6, 249 (2010)[2]M.V. Hauf et al., Phys. Rev. B 83, 081304 (2011)[3]M. Dankerl et al., Phys. Rev. Lett. 106, 196103 (2011)
N2: Nitrogen Vacancy Centres in Diamond
Session Chairs
Monday PM, November 28, 2011
Room 306 (Hynes)
11:30 AM - **N2.1
Diamond Nanophotonics and Quantum Optics.
Marko Loncar 1 , Tom Babinec 1 , Birgit Hausmann 1 , Jennifer Choy 1 , Irfan Bulu 1 , Yinan Zhang 1 , Qimin Quan 1
1 School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts, United States
Show AbstractIndividual color centers in diamond have recently emerged as a promising solid-state platform for quantum communication and quantum information processing systems, as well as sensitive nanoscale magnetometry with optical read-out. Performance of these systems can be significantly improved by engineering optical properties of color centers using nanophotonic approaches. In this work we describe a high-flux, room temperature, source of single photons based on an individual Nitrogen-Vacancy (NV) center embedded in a top-down nanofabricated, single crystal diamond nanowires1, 2, plasmonic nano-apertures3, and diamond-based optical cavities4 and waveguides. Using the nanowire geometry, for example, an order of magnitude brighter single photon source is realized, with an order of magnitude lower pump power, compared to an NV center in a bulk diamond1. By embedding diamond nanowires in metals3, it is possible to further increase photon flux by increasing photon production rate via Purcell effect. To that end, we demonstrated Purcell factors of ~6 in geometry that consists of diamond nanoposts embedded in silver. Finally, recently we demonstrated optical nanocavities and waveguides fabricated directly in thin diamond films5. Single-photon emission of NV centers embedded in diamond ring resonators, featuring quality factors on the order of 10,000, has been demonstrated. These devices could enable strong coupling between photons and NV centers. 1.T.M. Babinec, B.M. Hausmann, M. Khan, Y. Zhang, J. Maze, P.R. Hemmer, M. Lončar, Nature Nanotechnology, 5, 195 (2010) 2.B.J.M. Hausmann*, T.M. Babinec*, J.T. Choy*, J.S. Hodges, S. Hong, I. Bulu, A. Yacoby, M.D. Lukin, M. Lončar, New Journal of Physics, 13, 045004 (2011)3.I. Bulu, T.M. Babinec, B.M. Hausmann, J.T. Choy, M. Lončar, Optics Express, 19, 5268-5276 (2011)4.B. J. Hausmann, J. Choy, T. Babinec, Q. Quan, M. McCutcheon, P. Maletinsky, A. Yacoby, M. Loncar, CLEO/QuELS 2011, Baltimore, MD May 5, 2011
12:00 PM - N2.2
Electrical Tuning of Single Nitrogen Vacancy Center States Enhanced by Photoinduced Fields.
F. Joseph Heremans 1 , Lee Bassett 1 , Christopher Yale 1 , Bob Buckley 1 , David Awschalom 1
1 Center for Spintronics and Quantum Computation, University of California, Santa Barbara, Santa Barbara, California, United States
Show AbstractThe nitrogen-vacancy (NV) center in diamond is an excellent qubit candidate due to its long spin coherence, optical addressability, and fast manipulation rates, along with the engineering flexibility of solid-state devices. Furthermore, the coherent coupling of the electronic spin of a single NV center to light [1] provides a pathway towards integrating NV centers into photonic networks as well as for on-demand generation of spin-photon entanglement. Such applications require the ability to tune the NV-center optical transitions to compensate for the natural variations in local strain caused by sample inhomogeneities that perturbs the electronic orbital states. Here we demonstrate a method to electrically tune individual NV-center orbital Hamiltonians into specific regimes via the DC Stark effect by applying voltages to lithographic gates [2]. The DC Stark shifts reveal a significantly enhanced electric field due to the photoionization of deep charge traps within the diamond. These reproducible fields are predominantly directed perpendicular to the diamond surface allowing for three-dimensional control of the local electric field vector with surface gates only. By harnessing this effect, we are able to tune the excited-state orbitals of individual NV centers to degeneracy, a requirement for several spin-photon entanglement schemes. We also demonstrate the ability to tune multiple NV centers to the same degenerate transition energy. This method should enable the coherent coupling of multiple NV-center spins to indistinguishable photons within a photonic network.[1] B. B. Buckley, G. D. Fuchs, L. C. Bassett, and D. D. Awschalom, Science 330, 1212 (2010).[2] L. C. Bassett, F. J. Heremans, C. G. Yale, B. B. Buckley, and D. D. Awschalom, submitted (2011), arXiv:1104.3878v1 [cond-mat.mes-hall].
12:15 PM - N2.3
In Situ Optimization of NV-Center Creation.
Julian Schwartz 1 , Christoph Weis 1 , Thomas Schenkel 1
1 , LBNL, Berkeley, California, United States
Show AbstractThe NV-defect in diamond has been discussed as an excellent candidate for quantum-information processing at room-temperature. While creating these defect-centers by ion implantation with sufficient spatial resolution to enable entanglement is within reach, the challenge of deterministic creation (conversion efficiency >50%) remains. Increasing the conversion efficiency through co-implantation was studied using different co-implant species and fluences at room temperature and 780 C[1]. Despite the significantly different damage profiles of H, He and C, which were used for the co-implantation, the conversion efficiency did not show a species dependence and displayed similar trends across all combinations of parameters. This strongly indicates the additional effects of charging and possibly defect clustering, by which NV centers are prevented from forming or are trapped into an optically inactive state. We present first experimental results and discuss a strategic approach for investigating this phenomenon.This work was supported by the Laboratory Directed Research and Development Programof the Lawrence Berkeley National Laboratory under US Department of Energy contract no.DE-AC02-05CH11231 and through the DARPA Quest program.References[1] J Schwartz, P Michaelides, C D Weis and T Schenkel, New J. Phys.13, 035022 (2011)
12:30 PM - N2.4
The NV Color Center Qubit in Diamond as Readout for Molecular Qubits.
Wolfgang Harneit 1 2 , Rolf-Simon Schoenfeld 2 , Markus Nimmrich 1 , Angelika Kuehnle 1
1 Institut fuer Physikalische Chemie, Johannes Gutenberg-Univeritaet Mainz, Mainz Germany, 2 Institut fuer Experimentalphysik, Freie Universitaet Berlin, Berlin Germany
Show AbstractThe nitrogen-vacancy (NV) color center is a promising candidate for quantum information processing. Individual NV spins are very robust objects that can be coherently manipulated at room temperature, and used for fast and precise magnetometry. The only drawback of this solid-state qubit is that it cannot be created deliberately with atomic precision due to the inherent limitations of ion implantation. Molecular spin qubits, like the fullerene-encapsulated nitrogen atom N@C60, can be purified chemically and then placed on a Si surface with atomic resolution. The challenge of this project is to use the difficult diamond surface instead and engineer a coherent coupling between N@C60 and a shallow NV center. This would enable truly scalable quantum information processing.We have already achieved the first atomic resolution-imaging of single-crystalline diamond using non-contact AFM [1]. Using nanodiamonds (<50 nm diameter) as a model source for shallow NV centers, we demonstrated that even these slightly less advantageous qubits can be used at room-temperature in a quantum algorithm [2] and for magnetometry [3]. First steps to engineering the desired coupling will also be reported.References:[1] M. Nimmrich et al., Phys. Rev.B 106 (2010) 040504. [2] F. Shi, W. Harneit et al., Phys. Rev. Lett. 105 (2010) 040504.[3] R.S. Schoenfeld and W. Harneit, Phys. Rev. Lett. 106 (2011) 030802.
12:45 PM - N2.5
A Diamond Quantum Router of Single Photons at Room Temperature.
Birgit Hausmann 1 , Brendan Shields 2 , Qimin Quan 1 , Jennifer Choy 1 , Murray McCutcheon 1 , Patrick Maletinsky 2 , Tom Babinec 1 , Yiwen Chu 2 , Alexander Kubanek 2 , Amir Yacoby 2 , Mikhail Lukin 2 , Marko Loncar 1
1 SEAS, Harvard University, Cambridge, Massachusetts, United States, 2 Physics Department, Harvard University, Cambridge, Massachusetts, United States
Show AbstractWe present an all-diamond photonic platform on chip for single photon routing as well as broadband optical characterization. An all-diamond photonic network on chip requires coupling of a quantum emitter to a low-loss optical cavity that is efficiently coupled to a routing element such as a waveguide while offering scalability to obtain multi-coupling between resonators and routing elements preferably at room temperature for practical applications. Here, we combine room temperature operation with efficient routing of single photons from a Nitrogen-Vacancy (NV) defect center [1] that are emitted into the tightly confined mode of a high-finesse ring resonator and evanescently coupled to a waveguide [2]. The single photon flux is extracted efficiently via gratings. Our approach offers versatile scalability of elements. Room temperature routing of single photon flux opens up scenarios for photon entanglement created on chip and extracted in free space which opens up a new route towards quantum key distribution and perfectly secure quantum cryptography.We also present measurements demonstrating broadband operation of single diamond ring resonators on quartz substrate in a transmission tapered fiber set-up in the telecom regime as well as in a scanning confocal microscope in the VIS. Quality factors as high as 12000 were measured [3].
N3: Doping and Devices
Session Chairs
Monday PM, November 28, 2011
Room 306 (Hynes)
3:00 PM - **N3.1
Delta-Doped Diamond Transistor Design.
Etienne Gheeraert 1
1 Institut Néel, CNRS and University Joseph Fourier, Grenoble France
Show AbstractDiamond is a very attractive material for high power and high frequency electronic applications because of its exceptional physical properties. But diamond devices face one specific difficulty: at room temperature, because of the high ionisation energy of dopants, 0.38 eV for boron and 0.6 eV for phosphorus, free carrier density is very low at room temperature, and resistivity is consequently very high. Ionization energy can be reduced with an increase in the doping concentration, down to zero at the metal-insulator transition, but it also induces a detrimental decrease in the carrier mobility. The solution, proposed initially for silicon in the 80’s and then for diamond, is to fabricate a very thin heavily delta-doped layer in sandwich between two high purity diamond epilayers. The quantum confinement in this thin layer induces a delocalization of the free carriers out of the doped region, allowing holes to move into a high mobility diamond. If the doping level is high enough to reach the metal-insulator transition, ie 4e20 cm-3, then a high hole concentration is expected, even at room temperature. The first critical point is to get a quantum confinement strong enough to delocalize a significant part of the free carriers out of the delta layer. The second point is the ability to modulate the hole concentration with a top gate to build a field effect transistor.In order to get quantitative values regarding these two critical points, we simulated the delta structure solving the Schrödinger and Poisson equations consistently. From the quantum confinement of the hole wavefunctions and their occupancy ratio, the part of holes moving out of the delta layer was deduced, depending on the doping level and delta layer thickness. Then, the field effect control of the hole concentration was addressed. In particular, results show that the diamond breakdown field, even very high, limits the sheet carrier density in the structure, otherwise the field is not strong enough to deplete the channel and close the transistor. Detailed behaviour of the delta structure will be presented, and the transistor properties depending on device structure will be discussed.
3:30 PM - N3.2
Dopant Uniformity in Boron Doped Single Crystal Diamond Films.
Shannon Demlow 1 , Dzung Tran 1 , Nutthamon Suwanmonkha 1 , Isil Berkun 1 , Michael Becker 2 , Timothy Hogan 1 , Timothy Grotjohn 1 2
1 Department of Electrical and Computer Engineering , Michigan State University, East Lansing, Michigan, United States, 2 , Fraunhofer USA Center for Coatings and Laser Applications, East Lansing, Michigan, United States
Show AbstractDue to its superlative properties, such as a wide bandgap, high breakdown voltage, and high electron and hole mobilities, diamond is a potentially exceptional semiconductor for electronic applications, especially high-temperature and high-power devices. Doping issues continue to be a limitation in this field, and the realization of useful electronic devices requires high quality films with controlled and uniform dopant levels. Precision doping is of increasing concern, as delta, or nm scale, doping, has become an increasingly active area of research for enabling active diamond devices. In our previous work on characterization of boron-doped single crystal diamond (SCD), we have used temperature-dependent conductivity measurements to fit the activation energy, and investigated feedgas chemistries containing carbon dioxide for the control of doping for boron incorporation levels less than 1017 cm-3 [1,2]. We have also compared infrared absorption techniques and SIMS measurements for the determination of incorporated boron, and have shown that infrared absorption spectroscopy is sensitive to surface defects on grown samples [1].This work expands upon our previous effort to grow and characterize high-quality diamond for electrical applications. Films are deposited on high pressure high temperature SCD substrates in a microwave plasma-assisted CVD reactor with feedgas mixtures including hydrogen, methane, diborane, and carbon dioxide. The effect of carbon dioxide in the feedgas mixture on the incorporated boron is further investigated, and results showing the resulting decrease in electrically active boron are presented. We investigated the dopant spatial variation and the role of defect formation on boron incorporation, using infrared and Raman spectroscopy, conductivity and Hall effect measurements, secondary ion mass spectroscopy (SIMS) and scanning electron microscopy (SEM). We present the results of our investigation of the spatial uniformity of the dopant profile in boron doped diamond both across the growth surface and versus depth into the film, as well the properties of the boron doped layers as a function of temperature. Results for boron concentration levels ranging from below 1017 cm-3 to approximately 1020 cm-3 are reported. References[1] S.N. Demlow, M. Becker, and T. Grotjohn, Electrical Conduction Properties of Single Crystal, Boron-Doped Diamond Films, New Diamond and Nano Carbon Confernce (2011). [2] S.N. Demlow, T.A. Grotjohn, T. Hogan, M. Becker and J. Asmussen, Determination of Boron Concentration in Doped Diamond Films, MRS Proceedings (2011) 1282, mrsf10-1282-a05-15 doi:10.1557/opl.2011.444
3:45 PM - N3.3
Sharp Doped Delta Interfaces by Tuning the Species Residence Time.
Pierre-Nicolas Volpe 1 , Nicolas Tranchant 1 , Jean - Charles Arnault 1 , Christine Mer 1 , Samuel Saada 1 , François Jomard 2 , Philippe Bergonzo 1
1 , CEA - LIST, Gif sur Yvette France, 2 , GeMaC - CNRS, Meudon France
Show AbstractDelta doping of diamond is seen as a very promising route to fabricate novel generation power and electronic devices [1,2]. Nevertheless, the achievement of abrupt interfaces requires low residence time for involved species.We report on the growth optimisation of diamond boron doped single crystals in a MPCVD reactor where the gas injection has been especially designed to reduce the residence time of species in the substrate vicinity. This technique was applied to rising and descending boron profiles. Reflectometry and SIMS results will be shown with very promising profiles from 2*10^21 to 2*10^16 at/cm3 displaying doping gradients close to 3 nm/decade. [1] PN.Volpe, P.Muret, J.Pernot, F.Omnès, T.Teraji, F.Jomard, D. Planson, P.Brosselard, N.Dheilly, B.Vergne, S.Scharnholtz. Applied Physic Letters, 97, 22, 223501 (2010).[2] P. Muret, P.N. Volpe, T.-N. Tran-Thi, J. Pernot, C. Hoarau, F. Omnès, T. TerajiDiamond and Related Materials, 20, Issue 3, 285-289 (2011).
N4: Diamond Nanoparticles: Properties and Applications
Session Chairs
Monday PM, November 28, 2011
Room 306 (Hynes)
4:30 PM - **N4.1
Odour Monitoring Using Nanodiamond Based Gravimetric Sensor Arrays and Multiparametric Learning for Security Applications.
Emmanuel Scorsone 1 , Benoit Tard 1 , Philippe Bergonzo 1
1 , CEA-LIST, Gif-sur-Yvette France
Show AbstractGenerally speaking gravimetric gas sensors are made of a mass sensitive transducer, such as a micro-cantilever, quartz crystal microbalance or surface acoustic wave (SAW) device coated with a sensitive layer designed to have a high affinity with target molecules. The transducers are resonant devices which exhibit a shift in the resonant frequency upon mass loading when the gas molecules interact with the coating. High sensitivity is achieved both by the transducer and the coating whereas selectivity is mostly achieved by the coating. The design of highly specific sensors is only possible using coatings made of highly specific receptors. Unfortunately 100 % specific receptors or close only exist in biology and include antibodies, enzymes, DNA, etc. These receptors are generally not optimum for operation in the gas phase and their fairly short lifetime limits their use for field applications. Hence non biological receptors would be preferred, but unfortunately no such material has been shown to be 100 % specific to any volatile compound to date. Also the use of highly specific single sensors is not adequate for odor measurement which generally requires the detection of complex gas mixtures. An alternative approach consists of using a multisensor array. In this array, each sensor is coated with a different selective layer having each a broad selectivity to chemical compounds or families of compounds. The relative response signal of the sensors recorded simultaneously gives a fingerprint of a single gas or gas mixture. Combining this approach with data training and pattern recognition tools enables the discrimination of odors even though each individual sensor is not selective. The sensors used in this approach often take advantage of the availability of a wide range of polymers coatings but those feature a number of critical issues such as premature aging, poisoning, lack of reproducibility, etc. In the recent year we have developed alternative coatings made of functionalized nanodiamond. These are coated in particular onto highly sensitive 433 MHz SAW enabling the detection of hazardous volatile compounds in the low ppb range. The small size of the diamond nanoparticles enables high control of coating thickness hence a high level of reproducibility and high sensitivity due to high surface area. Moreover the sp3 nature of the grains offer a robust platform onto which can be immobilized a wide variety of receptors using the carbon chemistry via chemical or plasma routes that will be exposed. The diamond sensor arrays have allowed the selective detection of DMMP, a stimulant for sarin gas, as well as explosive vapors (EGDN, dynamite, etc.) for instance when hidden in a luggage. An insight toward the next generation diamond sensor arrays functionalized with highly stable odorant binding proteins will also be discussed.
5:00 PM - N4.2
Electrostatic Self-Assembly of Diamond Nanoparticles.
Oliver Williams 1 2 , Jakob Hees 2 , Armin Kriele 2
1 School of Physics & Astronomy, Cardiff University, Cardiff United Kingdom, 2 Micro and Nano Sensors, Fraunhofer IAF, Freiburg, BW, Germany
Show AbstractDiamond nanoparticles are exciting candidates for a diverse array of applications from single photon sources, through drug delivery and bio-labelling to the nucleation sites for growth of nanocrystalline diamond films. The apparent lack of toxicity, facile functionalisation strategies and stability makes them ideal bio-markers and drug delivery agents. The high quantum yield, photostability and fluorescence in the visible range are highly desirable optical properties for both bio-labelling and solid-state single photon sources.For both biological solution based colloids and solid-state substrate supported nanoparticle systems, the diamond nanoparticles must be individually accessible and treatable en masse. In both cases the nanoparticles are initially manipulated in colloidal dispersions and thus the nature of diamond nanoparticles in solution is critical. Unfortunately, diamond nanoparticles produced by the detonation process are tightly bound in aggregates that are difficult to separate into mono-disperse particle colloids. The aggregate size can be up to 100 nm in solution, far in excess of the 5 nm core particle sizes, rendering the dispersions inadequate for the majority of the aforementioned applications.Recently it has been shown that prior treatment of the particles by high temperature annealing in hydrogen gas or air can yield mono-disperse colloids of diamond nanoparticles. Although these approaches solve the colloidal dispersion issue, there is little information on the assembly of these nanoparticles at solid–liquid interfaces. This is a critical step for the production of high nucleation densities of diamond nanoparticles for the nucleation of nanocrystalline diamond films and reducing the nucleation density for discrete single photon emitters supported on quartz or other substrates. In this work we explain the mechanism behind the self-assembly of diamond nanoparticles onto silicon dioxide surfaces. Silicon dioxide is chosen due to it being the natural oxide of all silicon wafers and thus omnipresent in silicon supported diamond nanoparticle systems. It is also the most used transparent substrate for supported diamond nanoparticle single photon emitters. Characterisation of the zeta potential of both the diamond and silicon dioxide shows a clear pH window of electrostatic attraction, outside of which the system is unstable. By controlling the surface groups of the diamond nanoparticles and the pH of the solution, it is possible to yield either very high nucleation densities ideal for diamond growth (~1012cm-2) or low nucleation densities (<109cm-2) ideal for discrete single photon sources.
5:15 PM - N4.3
Detonation Nanodiamons: Properties and Selected Applications.
Robert Edgington 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractNanodiamonds (NDs), synthesized by a detonation process [1] are typically formed of 5nm core crystals tightly aggregated to sub-micron particles. Recent advances in the methods for treating these particles have enabled solutions of disaggregated NDs to be prepared [2], from which is it possible to coat 3D objects with NDs using simple room temperature sonication methods. In contrast, the deposition of thin film diamond using plasma-enhanced chemical vapour deposition (CVD) requires elevated temperatures (~8500C) ruling out many substrate materials, and complex plasma engineering for 3D coating. Hence, there is considerable interest in exploring the properties of NDs, and contrasting them to thin film diamond, and in applications for ND coatings on a wide range of substrates. In this paper, methods for producing and processing NDs will be reviewed, and the electrical properties of both aggregated [3] and monodispersed [4] forms of NDs considered. Interestingly, both forms of ND show properties remarkable similar to thin film diamond, in terms of their dielectric properties. Different forms of surface functionilisation of NDs, and the methods for producing them will be discussed. Diamond-based ISFETs have previously been demonstrated to be effective sensors, when the p-type conductive channel if formed by so-called ‘surface-transfer doping’ involved hydrogenation of the diamond surface. However, this form of device suffers from instability due to the need for an adsorbate layer to activate the doping process. We have recently shown that an ND coating on the gate region of such an ISFET obviates the need for such an adsorbate layer, leading to more stable ISFET operation [5]. We have recently reported upon the suitability of nanodiamond monolayers to act as a platform for neuronal cell growth [6]. Neurons cultured on various ND-coated substrates perform remarkably well, without the need for the standard protein-coated materials normally required for their initial cell attachment. Moreover, sustained neurite outgrowth, cell-autonomous neuronal excitability and excellent functionality of the resulting electrical networks result. Hence, it would appear ND layering provides an excellent growth substrate on various materials for functional neuronal networks and bypasses the necessity of protein coating, which promises great potential for chronic medical implants.[1] Shenderova et al Crit. Rev. Solid State Mater. Sci., 27, 227 (2002)[2] Williams et al Chem. Phys. Letts., 445, 255 (2007) [3] Bevilacqua et al Appl. Phys. Letts., 93, 132115 (2008) [4] Chaudhary et al., Appl. Phys. Letts., 96, 242903 (2010) [5] Ahmad et al Appl. Phys. Letts., 97, 203503 (2010) [6] Thalhammer et al, Biomaterials 31, 2097 (2010)
5:30 PM - N4.4
Surface Reconstruction and Selective Reoxidation on Annealed Detonation Nanodiamond.
Tristan Petit 1 , Jean-Charles Arnault 1 , Hugues Girard 1 , Mohamed Sennour 2 , Tsai-Yang Kang 3 , Chia-Liang Cheng 3 , Philippe Bergonzo 1
1 Diamond Sensors Laboratory, CEA-LIST, Gif-sur-Yvette France, 2 Paristech CNRS UMR 7633, Mines Paris, Evry Taiwan, 3 Department of Physics, National Dong Hwa University, Hua-Lien Taiwan
Show AbstractThe use of nanodiamond is very attractive for biomedical applications due to their unique surface chemistry and their fluorescent emitting centers like NV centers. The chemical reactivity of the sp3 carbon on the nanodiamond surface terminated with different groups such as carboxyls[1], hydroxyls[2] or hydrogen[3] is now well controlled and enables various functionalization routes. However it was shown recently that sp2 hybridized carbon on the nanodiamond surface could also lead to outstanding chemical[4] or catalytic[5] reactivities. If it is well-known that nanodiamonds are progressively transformed into Onion-Like Carbon (OLC) by annealing under vacuum at temperature above 1100°C[6], surface modifications of nanodiamonds occurring at temperatures below 1000°C remain unclear. This temperature range is though particularly interesting because it corresponds to the early stages of surface graphitization without alteration of the diamond core.In this study we investigate the surface modifications on detonation nanodiamonds induced by annealing under vacuum at temperature lower than 1000°C. We demonstrate by XPS, AES and HRTEM analysis that the nanodiamond surface reconstructs into graphitic nanostructures that can be controlled down to a single fullerene-like shell. Furthermore, we observed that after air exposure, the surface was spontaneously and selectively reoxidized. Consequently, the annealed nanodiamond could easily be suspended in water and have a highly positive zeta potential. The role of surface chemistry on the zeta potential change will also be discussed based on XPS, FTIR and DLS characterizations.1. Huang, L.-C.L. and H.-C. Chang. Langmuir, 2004. 20(14): p. 5879--5884.2. Krueger, A., et al. Langmuir, 2008. 24(8): p. 4200--4204.3. Girard, H.A., et al. Physical Chemistry Chemical Physics, 2011. 13(24): p. 11517-11523.4. Meinhardt, T., et al., 2011. 21(3): p. 494-500.5. Zhang, J., et al., Angewandte Chemie, 2010. 49(46): p. 8640-8644.6. Kuznetsov, V.L., et al., Journal of Applied Physics, 1999. 86(2): p. 863-870.
5:45 PM - N4.5
Fluorescent Nanodiamonds as Vector for siRNA Delivery to Ewing Sarcoma Cells.
Anna AlHaddad 2 , Marie-Pierre Adam 1 , Catherine Durieu 3 , Jacques Botsoa 1 , Géraldine Dantelle 4 , Sandrine Perruchas 4 , Thierry Gacoin 4 , Christelle Mansuy 5 , Solange Lavielle 5 , Claude Malvy 2 , Eric Le Cam 3 , Francois Treussart 1 , Jean-Rémi Bertrand 2
2 Laboratoire de Vectorologie et Théapeutiques Anticancéreuses, CNRS UMR8203, Université Paris Sud 11, Institut de Cancérologie Gustave Roussy, Villejuif France, 1 Laboratoire de Photonique Quantique et Moléculaire, CNRS UMR 8537, Ecole Normale Supérieure de Cachan, Cachan France, 3 Laboratoire de Signalisation, Noyaux et Innovations en cancérologie, CNRS UMR8126, Université Paris Sud 11, Institut de Cancérologie Gustave Roussy, Villejuif France, 4 Laboratoire de Physique de la Matière Condensée, CNRS UMR7643, , Ecole Polytechnique, Palaiseau France, 5 Laboratoire des Biomolécules, CNRS UMR7203, Université Pierre et Marie Curie,, Ecole Normale Supérieure, Paris France
Show AbstractNanotechnologies are opening new routes to the anti-cancer drug-delivery domain, providing a good tissue distribution and a low toxicity. Drug delivery vehicles relying on nanoparticles have been proposed, among which the one made of diamond (size<20 nm) is a promising candidate [1].We have investigated the delivery of small interfering RNA (siRNA) by nanodiamonds (ND) into cells in culture, in the context of the treatment of a rare child bone cancer (Ewing sarcoma) by such a gene therapy. siRNA is adsorbed onto the NDs after their coating with cationic polymers, so that the interaction is strong enough for the complex to pass the cell membrane without losing the drug, while not preventing its subsequent release.The cellular studies showed a specific inhibition of the gene expression by the ND-vectorized siRNA, at the mRNA and protein levels. The fluorescence of color center created in the nanodiamonds was used to monitor the release in the intracellular medium of fluorescently-labeled siRNA. This technique brings a quantitative insight in the efficiency of siRNA to stop cell proliferation [2].We also investigated in details the internalization process and the intracellular release of siRNA by the cationic NDs, using a combination of Transmission Electron Microscopy analysis, fluorescence microscopy and chromatography techniques. Different behaviors were observed depending on the type of cationic polymer, offering a tool for a better control of the delivery process.References[1] E.K. Chow et al., Sci Transl Med 3, 73ra21 (2011)[2] A. AlHaddad et al., submitted, arXiv:1106.2252v1 [q-bio.BM]
Symposium Organizers
Oliver A. Williams Cardiff University
Richard B. Jackman University College London
Philippe Bergonzo CEA-LIST
Greg N. Swain Michigan State University
Kian Ping Loh National University Singapore
N5: Electron Emission
Session Chairs
Tuesday AM, November 29, 2011
Room 306 (Hynes)
9:30 AM - N5.1
Secondary Electron Emission from Hydrogenated Nanocrystalline Surfaces: A Temporal Study.
Joseph Welch 1 , Aysha Chaudhary 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractSecondary electron emission from diamond surfaces which display negative electron affinity (NEA) can be used for the purposes of electron amplification. There are two approaches currently under investigation for the formation of stable NEA diamond surfaces. The first involves the addition of a monolayer of an alkali metal, such as Cs or Li, to the diamond surface. A simpler method involves hydrogenating the diamond surface. When sample surface is hydrogenated, the electron affinity drops so the diamond surface becomes NEA, which assists in the emission of the secondary electrons. Before any NEA is revealed any wetting layer, must be removed, since water adds on an extra layer of OH2 molecules, which constitutes a second capacitor. This capacitor is in series with the first capacitor of C-H, thereby increasing the surface electron affinity to positive (PEA). However, When primary electrons impinge onto the hydrogenated sample surface, the hydrogen desorbs over time, which in turn reduces NEA as the vacuum-barrier height becomes too high for the secondary electrons to escape.In this paper the temporal evolution of the secondary emission yield (SEY), or electron gain, is explored at different temperatues. Gains greater than 10 can be readily recorded, and it can be shown that the surface can be made sufficiently stable for some types of electron amplification applications, where low currents are used.
9:45 AM - N5.2
Diamond: Photocathode and Electron Amplifier.
John Smedley 1 , Ilan Ben-Zvi 1 , Xiangyun Chang 1 , Jonahan Rameau 1 , Triveni Rao 1 , Erdong Wang 1 , Qiong Wu 1 , Erik Muller 2 , Tianmu Xin 2
1 , Brookhaven National Laboratory, Upton, New York, United States, 2 Physics and Astronomy, Stony Brook University, Upton, New York, United States
Show AbstractDue to its ability to form a stable negative electron affinity (NEA) surface, diamond can operate as both an electron amplifier and as a photocathode. It has the potential to dramatically increase the average current available from photoinjectors, perhaps to the ampere-class performance necessary for flux-competitive fourth-generation light sources. We report on electron emission from hydrogen-terminated diamond, with both photon and electron generated carriers. An emission gain of over 200 has been achieved using a thermionic cathode; electron emission has also been observed with photon-generated carriers. The emission mechanism from H-terminated diamond has been investigated using Angle-Resolved Photoemission Spectroscopy, with both laser (6 eV) and synchrotron (12-20 eV) illumination. A novel emission mechanism relying on optical phonons to connect the conduction band minimum to the gamma point, allowing normal emission of electrons, has been identified. The implications of this mechanism on the function of the amplifier as an electron source will be discussed.
10:00 AM - N5.3
Ultraviolet Photodetector Driven by Diamond Cold Cathode.
Tomoaki Masuzawa 1 , Richika Kato 1 , Masanori Onishi 1 , Yuki Kudo 2 , Ichitaro Saito 3 , Takatoshi Yamada 4 , Ken Okano 1
1 Dept. of Physics, ICU, Tokyo Japan, 2 Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba Japan, 3 Dept. of Engineering, University of Cambridge, Cambridge United Kingdom, 4 Nanotube research center, National Institute of Advanced Industrial Science and Technology, Tsukuba Japan
Show AbstractRecent advances in optical engineering opened up various applications using ultraviolet (UV) light. These applications include a new generation optical storage device, UV photolithography, and medical diagnosis such as positron emission tomography (PET). For integrated devices, a common choice for a low-cost UV detector is a silicon (Si) avalanche photodiode (APD), though the relatively narrow band gap of Si tends to result in a high dark current. For such applications, solid-state APDs are intensively studied using wide-gap semiconductors, such as silicon carbide and various nitride materials [1][2]. In medical diagnosis, however, detection of weak UV light is becoming more important, and a demand in high sensitive photodetectors is much greater than that in fabrication cost or device size. In such field, photo multiplier tubes are still commonly used for their high gain (~1,000,000) and low dark current, even though they require high operation voltage of ~1kV and have slow response due to signal multiplication process. In order to develop a high-gain UV detector with low operation voltage and short response time, we propose a photodetector that consists of a diamond cold cathode and selenium-based photoconductive film.In our previous studies, we were focusing on fabrication of a photodetector, which is one of the practical applications of cold cathode, by combining a diamond cold cathode and an amorphous selenium (a-Se) photoconductor. The prototype photodetector showed a low operation voltage, and could detect visible lights of ~0.5 lx [3].In this study, an attempt was made to detect UV light using the prototype photodetector. Field emission characteristics of the detector are compared between under UV illumination versus no illumination. The result suggested an increase in the emission current with a fixed operating voltage, by the UV light illumination. This indicated that the fabricated prototype photodetector could detect UV light. Although the detection efficiency is not high compared to solid-state avalanche photodiodes in previous studies, drastic improvement in the detection gain is expected when the device is operated in the avalanche multiplication mode.[1] X. Xin et al., IEEE Electronics Letters 41 (2005) 212.[2] J. B. Limb et al., Appl. Phys. Lett 89 (2006) 011112.[3] N. Kato et al., J. Vac. Sci. Technol. B 24 (2006) 1035.
10:15 AM - **N5.4
Nanostructure TEM Analysis of Diamond Cold Cathode Field Emitters.
Travis Wade 3 , Nikkon Ghosh 1 , James Wittig 1 3 , Weng Kang 1 , Larry Allard 4 , Kinga Unocic 4 , Jim Davidson 1 3 , Norman Tolk 2 3
3 Material Science & Eng, Vanderbilt University, Nashville, Tennessee, United States, 1 Electrical Engineering, Vanderbilt University, Nashville, Tennessee, United States, 4 , Oak Ridge National Labs, Oak Ridge, Tennessee, United States, 2 Physics, Vanderbilt University, Nashville, Tennessee, United States
Show AbstractChemical vapor deposited (CVD) diamond is an attractive material for electron field emitters, in part because of its low or negative electron affinity, mechanical strength, and chemical inertness. CVD nanodiamond possesses unique properties including controlled sp2-carbon content and p-type electrical conductivity when doped with boron. Arrays of ultra-sharp diamond tips with a radius of curvature less than 5 nm have been fabricated and show significant improvement in emission brightness and turn-on field compared to other field emitters. Variation in field-dependent emission thresholds is considered to arise from variation in the geometric field enhancement factor of individual tips, followed by the additional emission of more tips as the field increases. However, above 5V/µm, all participating tips are observed to be active and electron emission behavior is consistent with the Fowler-Nordheim electron tunneling description. Irregularities in emission behavior between tips were historically attributed to anomalies in the fabrication process: “sharp” vs. “less sharp” tips. However, differences have been observed in electron emission thresholds between tips that appear to be equally well formed. This study examines the emitter to provide insight into how surface and subsurface structure may affect emission.Sub-surface parameters including dopant concentrations, oriented graphite present at grain boundaries on the diamond surfaces, and structural features such as voids, influence the transport of electrons to the emitter surface. As a principal mode of electron conduction in nanodiamond, the presence and orientation of graphite at the grain boundaries may substantially influence a tip’s electron emission behavior. Transmission electron microscopy performed in this study provides new insight into tip structure and composition with implications for field emission and diamond growth.
N6: Biosensors and Bioelectronics
Session Chairs
Tuesday PM, November 29, 2011
Room 306 (Hynes)
11:15 AM - **N6.1
Diamond and Graphene: Advanced Carbon Materials for Bioelectronics.
Jose Garrido 1
1 Walter Schottky Institut, TU München, Garching Germany
Show AbstractBiosensing and bioelectronic applications have enormously profited from employing field effect transistors as transducing devices, mainly due to their intrinsic amplification capability and the high integration offered by semiconductor technology. Due to the maturity of Si technology, most of the work with the so-called solution-gated field effect transistors (SGFETs) has been done based on Si-MOSFETs. However, several disadvantages of the Si technology, such as high electronic noise and poor stability, have motivated the search for more suitable materials. The sensitivity of SGFETs devices largely depends on the distance between the conductive channel and the surface. Therefore, the use of FETs structures with surface channels offer clear advantages. In this respect, the surface conductive channel of hydrogenated diamond appears as an ideal candidate for the development of highly sensitive SGFETs. Similarly, the surface conduction offered by graphene offers similar, if not better, potential. Furthermore, the facile integration of graphene electronics with flexible substrates might open the way for a true breakthrough in the field of electrically functional neural prosthesesIn this contribution, I will report on our work towards the development of graphene- and diamond-based platforms for applications in biosensing and bioelectronics. The electronic properties of graphene and diamond in contact with aqueous electrolytes will be discussed. It will be shown that the graphene/electrolyte and the diamond/electrolyte interfaces can be exploited for capacitive charging using a gate electrode to control the electrolyte potential, thus enabling the preparation of SGFETs. Graphene and diamond SGFETs will be compared to Si-SGFETs based on the gate sensitivity and low-frequency noise performance of these devices. Both diamond and graphene SGFETs will be shown to exhibit a high transconductance and correspondingly high sensitivity, together with an effective gate noise as low as tens of µV. Different cell types have been cultured onto graphene and diamond surfaces in order to assess the biocompatibility of these materials for those particular cell cultures. It was found that cells show a healthy growth comparable to standard glass substrates. Furthermore, we have investigated the ability of diamond and graphene SGFETs to transduce the electrical activity of electrogenic cells. To this end, cardiomyocyte-like HL-1 cells have been cultured on SGFET arrays. Employing the transistors beneath, we were able to detect and resolve the action potentials generated by the HL-1 cells. The propagation of the cell signals across the transistor array can be successfully tracked. These results demonstrate the potential of diamond and graphene to outperform state-of-the-art Si-based devices for biosensor and bioelectronic applications.
11:45 AM - N6.2
A Fully Ion Beam Micromachined Diamond Biosensor Designed for the Detection of Quantal Catecholamine Secretion from Chromaffin Cellschromaffin Cells.
Ettore Vittone 1 , Valentina Carabelli 2 , Emilio Carbone 2 , Sara Gosso 2 , Leonardo La Torre 3 , Paolo Olivero 1 , Federico Picollo 1 , Valentino Rigato 3
1 Expeirmental Physics Dept. and NIS excellence center, University of Torino, Torino Italy, 2 Department of Neuroscience, NIS Centre of Excellence , University of Torino, Torino Italy, 3 INFN- National Laboratories of Legnaro, University of Torino, Legnaro (Pd) Italy
Show AbstractIt is shown that ion beam direct writing of graphitic channels in monocrystalline diamond is an effective tool to fabricate sensors for biochemical analysis.A Ib monocrystalline diamond sample (3x3x0,5 mm3) was irradiated with a focused 1.6 MeV He ion beam scanned over a segmented path in order to define highly damaged regions with a resolution of the order of micrometer. A suitable variable thickness mask was used onto the diamond surface to modulate the penetration depth of ions and to shrink the damage profile toward the surface. After the irradiation, the sample was annealed at high temperature (> 800°C) to promote the conversion to the graphitic phase of the end-of range (about 3 micrometer in depth) regions which experienced an ion induced damage exceeding a damage threshold of the order of 1E23 vacancies/cm3 and to recover the sub-threshold damaged regions to the highly resistive diamond phase. This process provided buried highly conductive graphitic channels embedded in a highly electrically insulating and chemically inert diamond matrix, with end points (with dimension below 10 micrometer) emerging to the surface and available to be used as electrodes.The channels show a graphitic-like conductivity (around mOhmxcm); from amperometric characterization, the dark current recorded when one of the terminals was immersed in distilled water or in tyrode saline solution, was below 10 pA for a bias voltage of 800 mV with respect to a reference Ag/ClAg electrode.The microelectrodes show a high electrochemical responsiveness to oxidizable molecules as evaluated by recording the drift redox currents following the addition of consecutive micro-drops of adrenaline in proximity to the emerging channels.Finally, the functionality of these channels for the detection of bio-signals will be also tested by positioning adrenal chromaffin cells in the proximity of the emerging channels and recording the amperometric signals corresponding to the quantal release of catecholamines contained in a single secretory vesicle.
12:00 PM - N6.3
Electron Transfer between Diamond Electrodes and Biomolecules Immobilized via Conductive Polymer Brushes.
Andreas Reitinger 1 , Naima Hutter 2 , Franz Fuchs 1 , Andreas Donner 1 , Roberta Caterino 1 , Oliver Williams 3 , Martin Stutzmann 1 , Rainer Jordan 4 , Jose Garrido 1
1 Walter Schottky Institut, Technische Universität München, Garching Germany, 2 Wacker Chair of Macromolecular Chemistry, Technische Universität München, München Germany, 3 , Fraunhofer-Institut für Angewandte Festkörperphysik IAF Freibur, Freiburg Germany, 4 Chair of Macromolecular Chemistry, Technische Universität Dresden, Dresden Germany
Show AbstractThe development of diamond-based amperometric biosensors requires a precise control over the biofunctionalization of diamond surfaces [1]. In this work, we report on two routes to immobilize redox-active bio-molecules on or close to the surface of nanocrystalline diamond electrodes.
The first, more conventional, approach is based on a variety of relatively simple and small linker molecules, which in principle allows for a direct electron transfer between the coupled bio-molecules (including cytochrome c, horseradish peroxidise, and glucose oxidase) and the diamond electrode.
In the second approach we use polymer brushes to immobilize bio-molecules. In contrast to the immobilization based on small linker molecules, polymer brushes enable a much higher loading of biomolecules. Using self-initiated photografting and photopolymerization (SIPGP), brushes of polymers with lengths ranging from several nanometers to a few micrometers can be created on the diamond surface [2]. The SIPGP results in a strong covalent bond between polymer and diamond. We further demonstrate that biomolecules can be effectively incorporated into the polymer brushes [3]. However, when bio-molecules are immobilized along these polymers, an efficient electron transfer path between molecules further away from the surface and the diamond electrode has to be established. Here, we use ferrocene groups to mediate electrons along the polymers and compare different ways to integrate the ferrocene molecules into the polymer brushes. Having demonstrated the feasibility of this approach in principle, we will discuss the details of the electron transfer mechanism in these systems.
[1] A.Härtl et al., Nature Materials 3, 736 (2004)
[2] N.A. Hutter et al., Phys. Chem. Chem. Phys. 12, 4360 (2010)
[3] N.A. Hutter et al., Soft Matter 7, 4861 (2011)
12:15 PM - **N6.4
Covalently Functionalizing Graphene FETs for Real-Time Biosensing.
Paul Sheehan 1
1 U.S. Naval Research Laboratory, U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractThe sensitive and specific detection of biomolecules without using a label is a long-standing goal of the biosensors community. Several promising advances of the past several years formed biological field effect transistors (bioFETs) that have as the gate nanoscale materials such as nanowires and carbon nanotubes. The nanoscale dimensions of these materials allow the small charges associated with biomolecules to significantly change conduction through the gate. These conduction changes can be correlated with solution concentration to give precise readouts. While bioFETs are a promising way forward, there are many processing difficulties associated with these 1-D materials that inhibit large scale, reproducible fabrication of devices. Here, we will discuss our efforts to develop biosensors based on 2-D chemically modified graphene. These devices impart the sensitivity gains seen from other nanoscale materials, but offer a configuration that is amenable to processing techniques that are common in the semiconductor industry. We will focus primarily on chemically modifying graphene for attachment of biomolecular probes. Devices utilizing both graphene and graphene oxide will be covered, and surface spectroscopic studies of the material modification will be discussed. Successful results for the detection of specific DNA hybridization will also be presented, with detection limits that compare favorably with the best results reported from nanowire bioFETs.
N7: Diamond Growth
Session Chairs
Tuesday PM, November 29, 2011
Room 306 (Hynes)
2:45 PM - **N7.1
Novel Graphene and Nanodiamond Growth Strategies Using Large Area Linear-Antenna Microwave Plasma Enhanced CVD System.
Milos Nesladek 3 , Andy Taylor 1 , Frantisek Fendrych 1 , Otakar Frank 2 , Martin Kalbac 2 , Ladislav Kavan 2
3 IMO, Hasselt University, IMOMEC division IMEC, Diepenbeek Belgium, 1 Institute of Physics, Academy of Sciences of the Czech Republic, Prague Czechia, 2 Department of Electrochemical Materials, Academy of Sciences of the Czech Republic, Prague Czechia
Show AbstractGraphene growth for large-area electronic and optical applications has recently attracted much interest. Several growth strategies including chemical exfoliation, thermal CVD, plasma CVD and others have been used. Recently it has been suggested that graphene layers can be prepared by low pressure MW systems, such as slit-antenna delivery [1], at lower temperatures. However, the first results suggested also the presence of amorphous carbon in the atomic monolayers. In this work we study the use of a low pressure linear antenna MW plasma delivery system working in pulsed mode with CH4:H2 and CH4:Ar:H2 gas mixtures for the growth of graphene on Cu foils at Ts 400 - 700°C, subsequently transferring them to glass substrates. We have recently used this system for nanodiamond (ND) thin films growth. Firstly, we discuss the conditions leading to transition from ND to graphene growth. Secondly, we used Raman spectroscopy [3] to study transition from amorphous layers to graphene by optimising the growth conditions such as plasma parameters, gas composition and substrate temperature. For comparison we use thermal CVD to prepared graphene monolayers. Raman spectroscopy using various laser excitations shows very sharp graphene signatures at 1600 cm-1 and 2660 cm-1, pointing to high quality graphene layers. Additionally we use Photothermal Deflection Spectroscopy (PDS) to monitor optical absorption to follow the transition from amorphous graphene layers, showing the band-gap opening for low temperature layers (400 - 600 °C), to highly crystalline monolayers by changing the substrate temperature and plasma parameters in MW – LA PE CVD system.[1] Kim J, Ishihara M, Koga Y, et al. App. Phys. Lett. 98, 091502, 2011 [2] Taylor A, Fendrych F, Fekete L, et al., Diam. Related Materials 20, p 613-615, 2011. [3] Kalbac M, Farhat H, Kong J, et al., NanoLetters, 11 , p 1957-1963, 2011
3:15 PM - N7.2
Heteroepitaxial Growth of High Quality Diamond Films on Silicon Carbide.
Gary Harris 1 2 , Robert Westervelt 3 , Halvar Trodahl 3 , James Griffin 1 , Crawford Taylor 1
1 HNF, Howard University, Washington, District of Columbia, United States, 2 Electrical & Computer Engineering, Howard University, Washington, District of Columbia, United States, 3 Physics, Harvard University, Cambridge, Massachusetts, United States
Show AbstractDiamond films have a number of understanding mechanical, electrical and photonic properties. If these properties are to be realized a stable and controlled method of providing epitaxial films of diamond is required. In this paper, we report on the growth of diamond films grown on various polytypes of silicon carbide. The growth is carrier out in a microwave plasma chemical vapor deposition system. The effects of growth parameters on the grown film morphologies have been investigated. The substrate types include 6H, 4H and 3C, with doping ranging from semi-insulating to p and n type. The films have been fully characterized. Hall measurements, optical and electrical devices have been performed. The Raman spectrum and near band edge CL measurements have also been performed. The growth was carried out with methane and hydrogen as the carrier gas under pressures varying from 30-80 torr.
3:30 PM - N7.3
Characterization of Heteroepitaxial Diamond by Etch Pit Method.
Kimiyoshi Ichikawa 1 , Hideyuki Kodama 1 , Kazuhiro Suzuki 2 , Atsuhito Sawabe 1
1 Electrical Engineering and Electronics, Aoyama Gakuin University, Sagamihara Japan, 2 , Toplas Engineering Co. Ltd., Chofu Japan
Show AbstractLattice defect such as dislocation in heteropitaxial diamond plays a critical role in the degradation of electrical properties. Transmission electron microscopy (TEM) is the most effective on characterization of dislocation but requires skillful sample preparation. In general, etch pit method by defect-selective etching has been used to evaluate defect density and type in semiconductor materials. However, there have been a few reports on defect-selective etching of CVD diamond [1] [2]. We have already reported that etch pit can be formed on heteroepitaxial diamond surface by hydrogen plasma and etch pit density depended on the etching temperature [3]. In this study, we characterized lattice defects of nucleation side by hydrogen plasma and compared with of growth side. Heteroepitaxial diamond was grown on Ir(100)/MgO(100) substrate by d.c. plasma-assisted CVD at optimized condition with the thickness of 50µm. After the removal of substrate materials, free-standing diamond film has been divided in two samples and hydrogen d.c. plasma etching was carried out on the growth and nucleation side. Etching conditions are as follows; discharge current: 2100mA, gas pressure: 16kPa, substrate temperature: 1170K and etching duration: 2hrs. Observation of surface morphology and measurement of etch pit density on both side were done by AFM at arbitrary six different areas with 1µm in square. Inverted pyramidal shaped etch pits with the edge parallel to <110> were formed on the growth and nucleation side. Etch pit density on growth side was 8×108 cm-2 and on nucleation side was 8×1010 cm-2. The shape of etch pit were different on growth and nucleation side. Etch pits on nucleation side were rectangle while most of etch pits on growth side were square. We found out that etch pit density of growth side was smaller than that of nucleation side in two orders of magnitude. It might be originated from the facility of dislocation reduction in heteroepitaxial diamond because threading dislocations do not propagate mainly to growth direction. As the additional results, characterization of the etch pit by TEM will be presented on the day. References: [1] X. Jiang and C. Rickers, Appl. Phys. Lett. 75(1999)3935. [2] A. Tallaire, M. Kasu et al., Diam. Relat. Mater. 17(2008)60. [3] K. Ichikawa, A. Sawabe et al., Extended Abstract of 2010 Dia. Symp., 226 ( in Japanese)
3:45 PM - N7.4
Microplasma Arrays from CVD Diamond.
Paul May 1 , Mark Bowden 2 , Neil Fox 1 , Monika Zeleznik 1 , Robert Stevens 3 , Sebastien Mitea 2 , Judy Hart 1 , Chantal Fowler 3
1 School of Chemistry, University of Bristol, Bristol United Kingdom, 2 Department of Physics, The Open University, Milton keynes United Kingdom, 3 Micro and Nanotechnology Centre, Rutherford-Appleton Laboratory, Harwell United Kingdom
Show AbstractMicroplasmas are electrical discharges where the critical dimensions are less than 1 mm. Microplasmas based around a hollow-cathode design are extremely efficient, and as their size decreases, their operational pressure increases. For discharge cavities with dimensions of order 100 µm, operation has been demonstrated at atmospheric pressure. Fabricating thousands of these microplasmas on a large area substrate produces microplasma arrays. Such arrays may have a variety of potential applications, including removing contaminants from air supplies in enclosed environments (submarines, spacecraft), as flat panel light sources especially of near monochromatic light, as large area UV sources, and as small scale flow reactors for chemical processing. Until now microplasma arrays have been fabricated using Si or metals. We shall now present the results from the world’s first diamond microplasma discharge. Making the entire device electrodes and dielectric – out of doped and undoped diamond, respectively, allows easy fabrication and removes interface problems. The negative electron affinity of the H-terminated diamond surface also allows the device to strike at lower voltages than with other materials, whilst the robustness of diamond should increase device lifetime. This presentation shall discuss the issues surrounding this potentially new and exciting technology.
N8: Theory Meets Experiment
Session Chairs
Tuesday PM, November 29, 2011
Room 306 (Hynes)
4:30 PM - **N8.1
Diamonds Are Not Forever: An Atomistic View on Wear of Diamond.
Lars Pastewka 1 2 , Stefan Moser 2 , Peter Gumbsch 2 , Michael Moseler 2
1 Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland, United States, 2 , Fraunhofer IWM, Freiburg Germany
Show AbstractDiamond is the hardest material on Earth. Nevertheless, polishing diamond is possible with a process that has remained unaltered for centuries and is still used for jewellery and coatings: the diamond is pressed against a rotating disc with embedded diamond grit. Wear-rates, however, depend on the crystallographic orientation of the polished surface. This anisotropy is not fully understood and impedes diamond’s widespread use in applications that require planar polycrystalline films, ranging from cutting tools to confinement fusion. Molecular dynamics simulations reveal that polished diamond undergoes an sp3–sp2 order–disorder transition resulting in an amorphous adlayer with a growth rate that strongly depends on surface orientation and sliding direction, in excellent correlation with experimental wear rates. This anisotropy originates in mechanically steered dissociation of individual crystal bonds. Similarly to other planarization processes, the diamond surface is chemically activated by mechanical means. Final removal of the amorphous interlayer is proposed to proceed either mechanically or through etching by ambient oxygen.
5:00 PM - N8.2
Formation Conditions for Epitaxial Graphene on Diamond Substrates.
Karin Larsson 1 , Elizabeth Key 2 , Christoph Nebel 2 , Yang Song 1
1 , Materials Chemistry, Uppsala Sweden, 2 , Fraunhofer-Institute for Applied Solid State Physics , Freiburg Germany
Show AbstractGraphene has rather recently emerged as a new discovery and has attracted an avalanche attention because of the unique structural, physical and mechanical properties. The availability of samples of graphene has led to extensive exploration of electronic properties and novel transport phenomena in this material. Although several ways of producing graphene have been reported, none of them can be qualified as a high yield method. In this paper we present the possibilities for growth of epitaxial graphene on a non-terminated diamond (111) surface under the assumption of a high-temperature sublimation process. We apply annealing experiments at temperatures between 1200 and 1800 oC of diamond substrates in vaccum and in H2 atmosphere to investigate the formation of grapheme on diamond. The formation of grapheme is characterized using local etching in combination with AFM and white light interferrometry to measuere the layer thickness. The electronic properties are characterized by contact mode Atomic Force Microscopy (AFM) and the structural properties by confocal Micro-Raman scattering. These data are compared with results from theoretical modeling, where we have applied ab initio molecular dynamic simulations, including corrections for van der Waals interactions. They show that a temperature dependent graphitization will take place with start from the first C layer on the diamond surface. Graphene-like “bubbles” were initiated at ~500oC, which were fully developed at ~2000oC. Interstitial H within the diamond surface, positioned in the proximity to the surface-“grapheme” bonds did not result in major bond breakage. A higher H concentration led to H-termination of the bare parts of the diamond surface, and the saturation of the sp2 carbons in the graphene-like net. On the other hand, a high concentration of substitutional N resulted in a fast conversion to graphene.
5:15 PM - N8.3
Single Substitutional Nitrogen Defects Revealed as Electron Acceptor States in Diamond Using Ultrafast Spectroscopy.
Ronald Ulbricht 1 , Sietse van der Post 1 , Jon Goss 2 , P. Briddon 2 , Robert Jones 3 , Rizwan Khan 4 , Mischa Bonn 1
1 , FOM Institute AMOLF, Amsterdam Netherlands, 2 , Newcastle University, Newcastle United Kingdom, 3 , University of Exeter, Exeter United Kingdom, 4 , DTC Research Center, Berkshire United Kingdom
Show AbstractSingle substitutional nitrogen (Ns) constitutes the main impurity in diamond. It is known to form electron-donating states 1.7eV below the conduction band. We experimentally show that Ns can act as an electron acceptor, too.This feature can have implications for device applications. For example, negatively-charged nitrogen vacancy (NV-) centers in diamond are intensively studied for spintronics. NV- centers often show luminescence blinking which limits their use as stable emitters. This effect is believed to be due to the instability of their charge state. Since Ns defects are always present in diamond with NV- centers, their electron-accepting nature could potentially provide a pathway for the NV- centers to convert back to their neutral state.The electron dynamics in type Ib HPHT synthetic diamond (containing high Ns concentrations) were studied using ultrafast spectroscopy. We use techniques that excite electrons from Ns defects into the conduction band using femtosecond pulses of 3.1eV energy and probe the material response with picosecond time-resolution in the infrared and far-infrared part of the spectrum. The latter method is termed time-resolved terahertz spectroscopy which relies on measuring the conductivity of optically excited carriers using far-infrared probe pulses. We use it to record the picosecond dynamics of the electron back-relaxation from the conduction band.The results are combined with pump-probe studies that monitor the occupation of vibrational states of differently charged nitrogen states on comparable timescales. That allows us to track the electron relaxation pathways.Excited electrons are observed to recombine within tens of picoseconds. The recombination time is inversely proportional to the neutral nitrogen (Ns0) defect concentration and only weakly dependent on the density of excited electrons (which per definition equals the concentration of photogenerated positively charged nitrogen (Ns+) defect states). This suggests that most carriers recombine into Ns0 states rather than Ns+ states, thereby creating negatively charged nitrogen (Ns-) defects.After all electrons have relaxed, uncompensated Ns+ and newly created Ns- defects are present. The existence of these charged defects was confirmed by transient IR measurements employing infrared probe pulses. In this spectral region the localized vibrational modes (LVM) of charged nitrogen states show distinct signatures. It is known that Ns0 exhibits a peak at 1344 cm-1 and Ns+ at 1332 cm-1. When all electrons have recombined, the transient IR measurements showed an absorption peak at 1332 cm-1 originating from the LVM of Ns+ and a hitherto unknown absorption peak at 1349 cm-1 that is assigned to the LVM of Ns-. DFT calculations on the peak position of the LVM of Ns- are in good agreement with the found value. The Ns- defects are neutralized within 10 ns. This short lifetime may explain why Ns- defects have not been observed before in steady-state measurements.
5:30 PM - N8.4
Ab Initio Study on Silicon-Vacancy Defect in Bulk and Nano Diamonds.
Adam Gali 1 2 , Marton Voros 2
1 , Hungarian Academy of Science, Budapest Hungary, 2 , Budapest University of Technology and Economics, Budapest Hungary
Show AbstractSilicon-vacancy (Si-V) defect is an effective luminescence center indiamond known from decades, however, relatively little is known about theirground and excited state properties. Unlike the case of nitrogen-vacancy(N-V) center in diamond, there is still a debate in the literature whichcharge state of the Si-V defect contributes to the detected zero-phonon lineat 1.68 eV, for instance, and other important physical properties, like thehyperfine tensors of the proximate 13C isotopes around the defect are notknown in detail. Si-V defect may be an important alternative of N-V centerin quantum bit or, particularly, in biomarker applications. Recently,luminescent Si-V centers in ultrasmall nanodiamonds of diameter of 1.8nmhave been found that can be potentially a photostable substitution of recentunstable dye molecules applied for in vivo biological studies. However, itis not yet clear how the quantum confinement or the position of the Si-Vdefect within the nanodiamond affect the luminescence of this defect. Wecarried out accurate density functional theory (DFT) and time-dependent DFTstudies in order to determine the ground state properties and excitation ofSi-V defect in diamond. Our calculation provides the spin density distribution andhyperfine tensors for different charge states in bulk diamond. In addition, we calculated the formation energies and electronicstructure of Si-V defect in hydrogenated nanodiamonds of different sizes. Wefound that the quantum confinement effect is small and the nature of defectstates is atomic-like, thus the position of the defect within thenanodiamond may not change the spectrum significantly.
Symposium Organizers
Oliver A. Williams Cardiff University
Richard B. Jackman University College London
Philippe Bergonzo CEA-LIST
Greg N. Swain Michigan State University
Kian Ping Loh National University Singapore
N12: Poster Session - Diamond
Session Chairs
Wednesday PM, November 30, 2011
Exhibition Hall C (Hynes)
N9: Single Photon Centres in Diamond
Session Chairs
Wednesday PM, November 30, 2011
Room 306 (Hynes)
9:30 AM - N9.1
Formation of Single Crystal Diamond Micro-Disk Coupled to SiV Centers.
Jonathan Lee 1 , Andrew Magyar 1 , Igor Aharonovich 1 , Evelyn Hu 1
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
Show AbstractAccommodating a variety of color centers, single crystal diamond offers excellent potential for nano-photonic devices that will enhance our understanding of light-matter interactions in the solid state at room temperature. Examples of such color centers are the negatively charged Nitrogen-Vacancy (NV) complex with zero phonon line (ZPL) at 638 nm and the Silicon-Vacancy (SiV) complex with ZPL at 738 nm. Fabrication of diamond photonic devices offers exceptional challenges: it is desirable that the vertical dimension of the device be several hundred nanometers (on the order of a wavelength of the light modulated by the device), and these structures must be formed through processes that do not degrade the very sensitive color centers in the material. We describe a process that produces single crystal diamond micro-disks with quality factors (Q) ~ 2000, coupled to SiV centers. The starting material is a type II-a single-crystal diamond purchased from Element Six. Photoluminescence (PL) measurements of this material revealed the presence of NV centers, but no luminescence characteristics of SiV centers were observed. Single crystal diamond membranes, 1.7 microns thick, were generated by forming a sacrificial layer using ion implantation, followed by thermal annealing. The cap layer was lifted off through selective removal of the sacrificial layer using electrochemical etching. The membrane were then transferred onto a material with low index of refraction (SiO2) for optical isolation. These membranes served as templates for the epitaxial overgrowth of ~240 nm of diamond deposited by plasma-enhanced chemical vapor deposition. After the regrowth, the membranes were flipped, and thinned to a final thickness of 500 nm; thus the material comprised the regrown layer and about ~250 nm of the original diamond membrane material. PL measurement of the final membrane material displayed the characteristics of both NV and SiV centers. We believe that the SiV centers were introduced into the regrown diamond because of the presence of the underlying SiO2 layer during growth. Microdisk cavities with diameters ranging from 1.5 microns to 3.5 microns were subsequently formed from the thin, single crystal diamond membranes. Whispering gallery modes (WGMs) with Q ~ 2000 were experimentally measured from the diamond cavities using micro-PL spectroscopy. Spectral overlap of WGMs with the ZPL of SiV centers was observed. The demonstration of coupling between color centers in diamond and a single crystal diamond cavity is a crucial step towards scalable “all-diamond” integrated nano-photonic devices.
9:45 AM - N9.2
Ion-Implanted Xe Centers in Diamond: Dose Dependence and Conversion Efficiency.
Yury Deshko 1 2 , Alexander Zaitsev 1 2 , Mengbing Huang 3 , Anshel Gorokhovsky 1 2
1 , College of Staten Island, CUNY, Staten Island, New York, United States, 2 , The Graduate Center, CUNY, New York, New York, United States, 3 , University at Albany, SUNY, Albany, New York, United States
Show AbstractThe ion implantation and thermal annealing techniques allows one to introduce into diamond different color centers having emission lines in a broad spectral range, including near-infrared region. Focused ion implantation enables nanoscale patterning and may be used to fabricate single center optical emitters [1] and optical carbon nanostructures for quantum information processing [2]. On the other hand, ion implantation creates a number of radiation defects, which may affect optical and electrical properties of diamond. In this presentation we will report on photo-luminescence studies of Xe-ion implanted diamond crystals. The luminescence spectra and intensity dependences on implantation dose within the wide dose range of 1010 – 5x1014 ion/cm2 were investigated. The Xe color center is one of a few (Ni, Si, Cr) in diamond having sharp emission lines in the infrared spectral region. Moreover, a diamond LED activated with Xe color centers was demonstrated [3].At low temperatures, the photoluminescence spectra featured the extremely sharp single zero phonon lines at 811.7 nm and a weak phonon sideband. The room temperature luminescence consists of a zero phonon line at 813 nm and a weaker line at 794 nm. Our studies concluded that vacancies are involved in the formation of this defect, it contains a single Xe ion [4], and is a <111> oriented defect [5]. Likely, the stable configuration is the semi-divacancy site V-Xe-V [6].Probability of the implanted ions to convert into emitting color centers is difficult to measure. This quantity is particularly important for fabrication of devices based on emitting single centers and nano-optical structures by ion implantation. We used the method of micro-luminescence confocal mapping and statistical analysis based on the compound Poisson distribution to determine the conversion efficiency of implanted Xe ions into emitting Xe color centers, it was found to be about 0.3 [7]. This relatively low number may reflect the dynamic equilibrium between the creation and the decay of the emitting Xe centers at the annealing temperature of 1400 C, or a bottleneck due to the lack of vacancies. Additional experiments with the controllable vacancies concentration and different annealing temperatures are needed to understand the actual mechanism. This approach can be applied to any kind of color centers.[1] C. Wang, C. Kurtsiefer, H. Weinfurter, B. Burchard, J.Phys. B: At. Mol. Opt. Phys. 39, 37 (2006)[2] A. D. Greentree, B.A. Fairchild, F.M. Hossain, S. Prawer, Materials Today 11, 22 (2008)[3] A.M. Zaitsev, A.A. Bergman, A.A. Gorokhovsky, Mengbing Huang, Phys. Stat. Sol. (a) 203, 638 (2006)[4]A.A. Bergman, A.M. Zaitsev, A.A. Gorokhovsky, J. Lumin. 125, 92 (2007)[5]A.A. Bergman, A.M. Zaitsev, Mengbing Huang, A.A. Gorokhovsky, J. Lumin. 129, 1524 (2009)[6] A.B. Anderson, E. J. Grantscharova, Phys.Rev. B 54, 14341 (1996)[7] Y. Deshko, Mengbing Huang, A.A. Gorokhovsky, J. Lumin. 131, 489 (2011)
10:00 AM - N9.3
Fabrication of Thin Diamond Membranes for Quantum Information Processing.
Andrew Magyar 1 , Jonathan Lee 1 , Igor Aharonovich 1 , Evelyn Hu 1
1 , Harvard University, Cambridge, Massachusetts, United States
Show AbstractColor centers in diamond are leading candidates for the realization of quantum information processing. The formation of nanometer scale single crystal diamond membranes containing such centers is an important prerequisite for the fabrication of diamond based devices. However, sculpting diamond membranes from single crystal diamond is challenging, as diamond cannot be readily engineered to have sacrificial layers. Previous attempts to fabricate thin diamond membranes via ion implantation resulted in damaged diamond layers which typically did not show strong photoluminescence (PL). In this work we report a successful demonstration of engineering bright, nanometer scale diamond membranes. In our approach, firstly ion implantation is performed to critically damage a thin layer 1.7 μm below the diamond surface. The damage allows the selective etch and liftoff of the top diamond layer. The next crucial step involves positioning the membrane damaged side up and thinning via reactive ion etching to remove the most heavily damaged material. The Raman signal from the thinned membrane is close to that of a virgin crystal, indicative of high quality material. PL recorded from the membrane indicates the presence of the negatively charged nitrogen vacancy (NV) centers. The final thickness of the membranes approaches ~ 200 nm making them suitable for engineering optical cavities and waveguides. To further control the defect formation in the diamond membranes, the membranes are subjected to a short regrowth process in a conventional chemical vapor deposition reactor. The single crystal diamond membranes appear to serve as an excellent epitaxial template for the regrowth of single-crystal diamond films 150 nm to 1 μm in thickness. Examination of the regrown films alone indicates the presence of other optically active defects, such as Si-vacancy centers, as well as NV centers that demonstrate good electron spin resonance signatures. Further experiments will correlate regrowth conditions with the defects and optical properties of the membranes. This powerful method can be fully utilized to incorporate other defects into thin diamond membranes and proceed with fabrication of diamond photonics devices.
10:15 AM - N9.4
Towards a Better Understanding of the Vacancy Defects Formed in Diamond by 2.4 MeV Proton Irradiation, Using PAS and PL Investigation.
Jacques Botsoa 1 2 , Thierry Sauvage 1 , Mohamed-Ramzi Ammar 1 , Blandine Courtois 1 , Pierre Desgardin 1 , François Treussart 2 , Marie-France Barthe 1
1 Conditions Extrêmes et Matériaux : Haute Température et Irradiation, CNRS UPR 3079, Université d'Orléans, Orléans France, 2 Laboratoire de Photonique Quantique et Moléculaire, UMR 8537 CNRS/ENS Cachan, Cachan France
Show AbstractThe production of a high density of the negatively charged nitrogen vacancy color center (NV-) in diamond is very attractive for applications as diverse as the realization of hybrid quantum circuits [1], ultra-sensitive magnetometry at the micrometer scale [2] and bio-imaging [3]. In this context, a minimum understanding and control of the production of these centers in diamond is necessary.Doppler Broadening Positron Annihilation Spectroscopy (PAS) and confocal photoluminescence (PL) spectroscopy have been used to study different type 1b diamond samples that have been irradiated with a 2.4 MeV proton beam at fluences ranging from 1×1012 cm-2 to 1×1017 cm-2, annealed under vacuum at temperatures ranging from 600°C to 1000°C during times varying from 1 to 20 hours.These studies allowed us to highlight the formation of divacancies for high proton fluences (≥ 5×1014 cm-2), which limits the concentration of NV- produced upon annealing to a maximum of 14 ppm. Along the way, we deduced the positron annihilation characteristics of the NV- center, in particular the positron trapping coefficient [4].Using these data, we were also able to infer a measurement of the concentration of the monovacancies formed upon irradiation at low proton fluences, which appears to be three times lower than the one predicted by the Stopping and Range of Ions in Matter (SRIM) Monte Carlo simulations. The depth profiles of the PL intensity of NV- centers, measured in samples prepared under different conditions, also show discrepancies with the SRIM predictions.Moreover we inferred the positron annihilations characteristics of the divacancy in diamond from which we estimated the divacancy concentration. Finally we studied the stability of the divacancies, upon annealing at temperatures higher than 1000°C.References[1] Y. Kubo et al., Phys. Rev. Lett.105, 140502 (2010)[2] V. M. Acosta et al., Appl. Phys. Lett. 97, 174104 (2010) [3] Y. –R. Chang et al., Nature Nanotech. 3, 284 (2008)[4] J. Botsoa et al, submitted, arXiv:1105.0092 [cond-mat.mtrl-sci]
10:30 AM - N9.5
Substitutional Nickel Impurities in Diamond: Decoherence-Free Subspaces for Quantum Information Processing.
Thomas Chanier 1 , Craig Pryor 1 , Michael Flatte' 1
1 Physics, University of Iowa, Iowa City, Iowa, United States
Show AbstractSpin centers based on single impurities or impurity complexes in diamond have been extensively explored as qubit candidates due to effective optical access and extremely long room-temperature spin coherence times. In other material systems the coherence times and fidelity for quantum operations of qubits has been improved dramatically through the use of decoherence-free subspaces of exchange-coupled spins to form a qubit; one example is the use of the spin singlet state and the Sz = 0 state of a spin triplet to form a decoherence-free subspace for two electrons confined to two neighboring quantum dots[1,2].These approaches rely on the ability to control the exchange interaction between two spins, such as by using an electrical gate to modulate the electronic hopping from one quantum dot to another. Such an approach is challenging for a spin center in diamond, for the typical size of the electronic wave functions is very small, and gating technology is not well advanced. Strain provides an alternate mechanism for controlling a spin center, as was recently shown via electrically-detected magnetic resonance induced by strain control of the hyperfine constant of a 31P+ donor in strained Si[3].Here we show, using density functional theory calculations, that the substitutional nickel impurity in diamond can be understood as an exchange-coupled system of two electron spins: one localized on the nickel ion and one delocalized on the four nearest-neighbor carbon atoms. The electronic configuration of Ni is unambiguously determined as a p−d hybridization between the Ni 3d and nearest-neighbor carbon 2p levels. Although the ground state at ambient pressure for the neutral nickel impu- rity has been predicted to be a spin-one center[4], the spin-zero state is nearly degenerate, and can be made degenerate through the application of reasonable compressive hydrostatic strain. To reduce to an effective two- state decoherence free subspace, similar to that implemented for quantum dots[2], the m = ±1 triplet states can be split off by a magnetic field. For the nickel ion, strain can be used to control the energy splitting between the singlet and the remaining m = 0 triplet, instead of the electrostatic gating used for double quantum dots[2]. The spin-one state consists of two electrons with parallel spins, one on the nickel ion in the 3d9 configuration and the other distributed among the nearest-neighbor carbons; the slightly different g factors we found for these two spins provides an orthogonal axisof control in the effective two-state decoherence-free sub- space of the nickel ion.[1] J. Levy, PRL 89, 147902 (2002). [2] J. R. Petta et al., Science 309, 2180 (2005). [3] L. Dreher et al., PRL 106, 037601 (2011). [4] R. Larico et al., PRB 79, 115202 (2009).
10:45 AM - N9.6
Electrical Tunability and Correlation Spectroscopy of Single-Photon Emission from Chromium-Based Colour Centres in Diamond.
Tina Muller 1 , Clemens Matthiesen 1 , Yury Alaverdyan 1 , Nick Vamivakas 1 , Mete Atature 1 , Igor Aharonovich 2 , Stefania Castelletto 2 , Steven Prawer 2
1 Cavendish Laboratory, University of Cambridge, Cambridge United Kingdom, 2 School of Physics, University of Melbourne, VIC 3010, Victoria, Australia
Show AbstractChromium based single photon emitters have recently attracted attention as alternatives to the well-investigated NV centre with potentially superior photonic properties. We show that using the electrical Stark shift these centres can be tuned over a spectral range typically three orders of magnitude larger than the radiative linewidth and at least one order of magnitude larger than the observed linewidth. Interdigitated gold gates fabricated on the single crystal diamond are used to apply electrical fields up to 8.5 x 10E6 V/m, and the polarity can be reversed by applying a reverse bias. The linewidth of the centre remains unchanged under an electric field, and the asymmetric nature of the linear dipole response allows us to infer an atomic configuration lacking inversion symmetry. Based on this and the fabrication protocol we propose a Cr-X or X-Cr-Y type atomic structure for these Cr-based centres, where X and Y are likely to be oxygen, nitrogen or sulphur. We further characterise the emission properties of chromium centres using a Michelson interferometer for first order correlation (g(1)) measurements of single-photons from chromium centres in diamond microcrystals. The extracted visibility predominantly follows a Gaussian statistics with coherence times on the order of 100 ps. This translates to a spectral linewidth of about 16 GHz which is considerably broader than the 80 MHz expected for a lifetime-broadened line, indicating that the predominant line broadening mechanism in this case is likely to be slow wandering of the resonance caused by fluctuations of the charge environment.
N10: Boron Doped Diamond Electrodes for Biological Applications
Session Chairs
Wednesday PM, November 30, 2011
Room 306 (Hynes)
11:30 AM - **N10.1
New Diamond Surface Derivatization for Biosensor Fabrication.
Charles Agnes 1 2 4 , Sébastien Ruffinatto 1 2 , Alexandre Bongrain 3 , Jean-Charles Arnault 3 , Franck Omnes 1 , Pascal Mailley 2 , Serge Cosnier 4 , Philippe Bergonzo 3
1 , Neel Institute - CNRS, Grenoble France, 2 INAC, CEA, Grenoble France, 4 DCM, CNRS - UJF, Grenoble France, 3 LIST, CEA, Paris France
Show AbstractDiamond is a promising material exhibiting superior electrochemical properties such as low background current, wide potential window and low sensitivity to oxygen evolution. Associated to its carbon nature enabling covalent surface functionalization, boron doped diamond (BDD) is a material of choice for electroanalysis and for interfacing with (bio-) molecular entities.Usual approach for diamond functionalization are based on alkenes photochemistry [1] and diazonium salts [2,3]. However, these methodologies follow long and complex multistep strategies. We have recently developed a novel one-step derivatization strategy that is fast (less than 2 minutes), selective, leading to a monolayer covalently linked to the surface, and compatible with patterning approaches. Different (bio-) molecules were immobilized on diamond surfaces and characterized using fluorescence spectroscopy, electrochemistry, FTIR and XPS. Their stability and bioactivity was demonstrated using the avidin-biotin couple. This opens up the route for the fabrication of biosensors, where the transduction can be based on cantilever approaches. For example, single strained DNA and antibodies can be immobilized using our approach on sensors and applied to demonstrate the selectivity and the ability of this new method for DNA and cell recognition. In parallel, redox enzymes were also immobilized enabling the fabrication of second- and third-generation amperometric enzymatic biosensors.[1] Yang et al, Nature Mat., 1 (2002) 253 [2] Rezek et al, J. Am. Chem. Soc., 128 (2006) 3884 [3] Lud et al, J. Am. Chem. Soc., 128 (2006) 16884
12:00 PM - N10.2
Electrochemical Oxidation of Organic Compounds in Water Using Boron-Doped Diamond Electrodes.
Jorge Lara 1 , Manoj Ram 1 , Pedro Villalba 1 , Mikhail Ladanov 1 , Kumar Ashok 1 2
1 Engineering, USF, Tampa, Florida, United States, 2 Nanotechnology Research and Education Center, University of South Florida, Tampa, Florida, United States
Show AbstractThe electrochemical process for wastewater-cleaning comprehends a wide diversity of pollutant organic compounds, where their destruction may vary in different ways i.e. chemical and physical conditions, transformation mechanics, and the uses of any specific type electrode material, e.g. active or non-active type electrodes. Boron-doped diamond (BDD) synthesized by CVD technique is of interest in this work due the significant features claimed for this material i.e., chemical inertness, the higher overvoltage withheld before the O2 production potential region and vital oxygen loss. The high resistance to deactivation via fouling comparatively with other carbon allotropes, metallic and metal-oxide electrodes, yet is subject of study and efforts are made in the way of the optimization for the application in the electrochemical field. In this particular case, the oxidation of organic matter or at least the conversion of toxic organics to biocompatible and less toxic compounds is possible with the use of BDD films electrode.We have used BDD films in order to electrochemically oxidize the common chemicals, i.e., xylene and acetic acid. A conventional set up of three-electrode electrochemical cell was used consisting of microcrystalline boron-doped diamond film as anode, platinum as cathode and Ag/AgCl as reference electrode in electrolytic acid medium. The as prepared test solutions and diamond thin films were subjected to repeated voltammetric cycles at predefined scan rate from 1 V to a maximum of 2.5 V vs. Ag/AgCl, aimed to identify the characteristic redox signals coming from the organic solutes tested and/or the intermediate species. The characteristic signals of organics in water seem to happen within the anodic potential region just below the electrolyte stability potential. Attempts are made to characterize the water using GC-MS to understand the presence of the chemicals. The diamond films used in electro-oxidation potential were characterized using Raman spectroscopy, glancing-angle x-ray diffraction (GIXRD) and scanning electron microscopy (SEM) to explore the electrode’s stability after water remediation process.
12:15 PM - N10.3
Simultaneous Determination of Uric Acid and Ascorbic Acid in Urine with In Situ Cleaning Using BDD Electrode.
Raphael Kiran 1 , Emmanuel Scorsone 1 , Jacques DeSanoit 1 , Pascal Mailley 2 , Philippe Bergonzo 1
1 , CEA, LIST, Diamond Sensors Laboratory, Gif-sur-Yvette France, 2 , CEA, INAC, SPrAM UMR 5819 (UJF,CNRS, CEA) , Grenoble France
Show AbstractUric acid (UA) and Ascorbic acid (AA) are the common antioxidants found in human urine. High levels of UA (hyperuricemia) can cause Gout, cardiovascular disease, stone formation etc. whereas hypouricemia can cause xanthinuria, kidney disorder etc. Similarly deficiency of AA causes scurvy. Hence it is important to monitor their level in bodily fluids such as urine. Electrochemical detection technique is more suitable due to their good sensitivity, fast measuring time, portability, low power consumption and cost effectiveness when compared to spectroscopic, colorimetric, enzyme based sensors. Boron doped diamond (BDD) with its electro-analytically superior properties such as low background current, low adsorption of species and long term stability, makes it the ideal electrode for this sensor. However there are some difficulties associated with electrochemical measurement technique such as interference of UA and AA oxidation peak and fouling of the electrode surface. Cyclic voltammograms of both UA and AA (in PBS solution pH = 7.4) indicated an oxidation peak (P1) at ~0.6 V versus Ag/AgCl. However at higher scan rate (>0.5 V/s) a reduction peak (P2) was observed at ~0.1 V versus Ag/AgCl only for UA. The amplitude of P1 was proportional to concentration of UA and AA whereas P2 was proportional to concentration of UA and inversely proportional to concentration of AA. Two calibration surface plots with x axis being concentration of UA, y axis being concentration of AA and z axis being P1 and P2 respectively were plotted. UA and AA concentration can be estimated from the equations governing the graph. BDD electrode is prone to fouling due to deposition of organic molecule which causes lose of electrode reactivity and produce inaccurate results. However with an electrochemical (EC) activation process the electrode can be reactivated. This technique does not need any particular solvent and hence it can be done within the analyte (urine). The time taken for measurement and cleaning is less than 0.5 seconds and this technique can be automated for real time quantification. The measurement and in-situ EC activation technique will be discussed in detail. This technique highlights the potential of BDD electrodes as a biosensor owing to its low double layer capacitance (3µF/sq.cm), robustness at high current density and corrosion resistance.
12:30 PM - N10.4
Fast Detection of Single Nucleotide Polymorphisms by Electronic Monitoring of Denaturation.
Bart van Grinsven 1 , Natalie Vanden Bon 2 , Lars Grieten 1 , Mohamed Murib 1 , Stoffel Janssens 1 , Ken Haenen 1 3 , Eric Schneider 4 , Sven Ingebrandt 4 , Michael Schoning 5 , Veronique Vermeeren 2 , Marcel Ameloot 2 , Luc Michiels 2 , Ronald Thoelen 1 , Ward De Ceuninck 1 3 , Patrick Wagner 1 3
1 Institute for Materials Research, Hasselt University, Diepenbeek Belgium, 2 Biomed, Hasselt University, Diepenbeek Belgium, 3 IMOMEC, IMEC, Leuven Belgium, 4 Informatics and Microsystems Technology, University of Applied Sciences Kaiserslautern, Zweibrucken Germany, 5 Nano- and Biotechnologies, Aachen University of Applied Sciences, Julich Germany
Show AbstractWithin this presentation we would like to report on the electronic monitoring of DNA denaturation by NaOH using electrochemical impedance spectroscopy in combination with fluorescence imaging as a reference technique [1]. The probe DNA consisting of a 36-mer fragment was covalently immobilized on nanocrystalline-diamond electrodes and hybridized with different types of 29-mer target DNA (complementary, single-nucleotide defects at two different positions, and a non-complementary random sequence). The mathematical separation of the impedimetric signals into the time constant for NaOH exposure and the intrinsic denaturation-time constants gives clear evidence that the denaturation times reflect the intrinsic stability of the DNA duplexes. The intrinsic time constants correlate with calculated DNA-melting temperatures. The impedimetric method requires minimal instrumentation, is label-free and fast with a typical time scale of minutes and is highly reproducible. The sensor electrodes can be used repetitively. These elements suggest that the monitoring of chemically induced denaturation at room temperature is an interesting approach to measure DNA duplex stability as an alternative to thermal denaturation at elevated temperatures, used in DNA-melting experiments and single nucleotide polymorphism (SNP) analysis.[1] B. van Grinsven et al., Lab Chip, 2011, 11, 1656
12:45 PM - N10.5
Soft Diamond Microelectrode Arrays for Neural Stimulation: Application to Retinal Implants.
Philippe Bergonzo 1 , Raphael Kiran 1 , Alexandre Bongrain 1 2 , Emmanuel Scorsone 1 , Amel Bendali 3 4 , Lionel Rousseau 2 , Gaelle Lissorgues 2 , Blaise Yvert 5 6 , Serge Picaud 3 4 7
1 , CEA-LIST, Gif-sur-Yvette France, 2 , ESIEE-ESYCOM, Noisy le Grand France, 3 , INSERM U968, Paris France, 4 , UPMC, Paris France, 5 Institut des Neurosciences, Université de Bordeaux, Bordeaux France, 6 , CNRS - INCIA, Bordeaux France, 7 , Fondation Rothschild, Paris France
Show AbstractWe report on the fabrication of Micro-Electrode Arrays (MEA) that takes advantage of synthetic conducting diamond when used as bio-interfacing material. Diamond enables the fabrication of electrodes with high biocompatibility, high electrochemical interfacing performances and long-term stability. We developed diamond based MEAs for recording and stimulating of neuron networks for both in vitro applications (rigid substrate) as well as for in vivo retinal prostheses (flexible biocompatible substrate).
N11: Nanodiamond Applications
Session Chairs
Wednesday PM, November 30, 2011
Room 306 (Hynes)
3:00 PM - N11.1
Nanodiamond for Advanced Polymer-Matrix Composites.
Vadym Mochalin 1 , Ioannis Neitzel 1 , Qingwei Zhang 2 3 , Jack Zhou 2 , Peter Lelkes 3 , Yury Gogotsi 1
1 Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania, United States, 2 Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania, United States, 3 School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractDiamond particles smaller than 10 nm (ND) have remarkable optical and mechanical properties in combination with biocompatibility, high specific surface area, and tunable surface structure. They are the least toxic of all carbon nanoparticles and their properties make them a favorable platform for composites, drug delivery and cellular labeling/imaging. However, to harness the potential of ND in advanced composite and biomedical applications it needs to be purified, characterized, and functionalized.Purified and octadecylamine (ODA) functionalized ND (ND-ODA) was used to produce stable colloidal solutions and uniform dispersions in hydrophobic solvents and biodegradable hydrophobic polymer poly (L-lactic acid) to create a material for screws, pins, and other bioresorbable surgical devices. In this application ND-ODA functions as i) mechanical reinforcement, bringing the Young’s modulus and hardness of the composite close to that of human bone; ii) a means of monitoring performance of the device due to intrinsic fluorescence of ND-ODA. In addition to improvements in ND dispersion due to non-specific interactions with the polymer, a different strategy can be employed whereupon ND is functionalized to specifically interact with certain functional groups of the polymer, forming covalent bonds between the ND and polymer molecules. For the latter purpose aminated ND was produced and incorporated into a 3-D network of epoxy, acting as a nanoparticulate curing and reinforcing agent. Due to the presence of reactive amino groups on its surface, aminated ND interferes with epoxy curing chemistry, making it necessary to adjust epoxy resin : curing agent ratio to achieve optimal properties of the composite. With the adjustment been made, the resulting composite shows clear improvements in Young’s modulus, hardness, and creep rate, revealing the advantages of covalent ND-polymer interface.
3:15 PM - N11.2
A Novel Method for Selective Seeding of Nano-Diamond Particles.
Thijs Vandenryt 1 2 , Lars Grieten 1 , Stoffel Janssens 1 , Ken Haenen 1 3 , Patrick Wagner 1 3 , Ward De Ceuninck 1 3 , Ronald Thoelen 2
1 IMO - Institute for Materials research, Hasselt University, Hasselt Belgium, 2 EMAP, XIOS Hogeschool Limburg, Diepenbeek Belgium, 3 IMOMEC, IMEC, Diepenbeek Belgium
Show Abstract In this contribution a novel method for selective seeding of nano-diamond particles is presented. Williams et al. [1] improved the nucleation density of the NCD films by seeding with a colloidal suspension of diamond nanoparticles. In order to produce patterned diamond structures, a lithographical procedure is indispensable. Bongrain et al. [2] have shown two alternatives to conventional etching techniques: selective seeding. Unfortunately both techniques require extensive sample preparation and complex pre/post-nucleation treatment steps.The method proposed in this abstract takes a novel route to create patterned nano-diamond surfaces with possibilities for a broad range of applications. The combination of microfluidics with the seeding of diamond nanoparticles yields a cheap, high resolution and high throughput application without any complicated pre- or post-treatment of the seeded surface. After chemical vapor deposition with a 3 % methane/hydrogen concentration the diamond film structures have a thickness of about 100 nm. These structures have a remarkable high resolution with well-defined edges and form a completely closed structure without pinholes. Additionally, there is little or no reseeding or spontaneous nucleation of the diamond substrate. To conclude, in the proposed technique there is no need for optical lithography, ablation/etching techniques or surface modification before or after growth. The elimination of these steps speeds up the production of functional diamond devices considerably. This technique can be integrated in industrial processes to facilitate the production of diamond to be used in MEMS and electronic applications.[1] Oliver A. Williams et al 2007 Chem. Phys. Lett. 445 (4-6)[2] Alexandre Bongrain et al 2009 J. Micromech. Microeng. 19 074015
3:30 PM - N11.3
Focused Ion Beam (FIB)-Assisted Fabrication of Combined Boron-Doped Diamond AFM-SECM Probes: Characterization and Application.
Alexander Eifert 1 , Waldemar Smirnow 2 , Boris Mizaikoff 1 , Christoph Nebel 2 , Christine Kranz 1
1 Institute of Analytical and Bioanalytical Chemistry, University of Ulm, Ulm Germany, 2 , Fraunhofer Institute for Applied Solid State Physics, Freiburg Germany
Show AbstractRecent research in atomic force – scanning electrochemical microscopy (AFM-SECM) is mainly focused on improving the lateral resolution of AFM and SECM imaging, and strategies for improving mass production of bifunctional AFM-SECM probes. Still, optimized physical and chemical properties are a prerequisite for reliable simultaneous data acquisition in AFM-SECM measurements. Recently, fabrication schemes for integrating boron-doped diamond electrodes in AFM probes have been demonstrated [1,2]. Hereby, the electrode was either merged with the AFM tip apex [1] or recessed from a non-conductive diamond tip [2]. So far, a thorough characterization and imaging with BDD-AFM-SECM probes have not been fully presented. Hydrogen-terminated highly doped microcrystalline boron-doped diamond is generated via plasma enhanced chemical vapor deposition (PECVD). BDD-electrodes open a wide range of applications for combined AFM-SECM measurements due to the durability, chemical inertness and electrochemical properties of the material. In this contribution, first results on FIB-based fabricated BDD-AFM-SECM probes using different insulation schemes will be presented. As surface termination plays a significant role in the electrochemical behavior of BDD-electrodes, surface treatments after FIB-milling in order to recover surface properties will be discussed. Furthermore, a thorough electrochemical characterization, theoretical diffusion and current simulations and also imaging applications will be presented.[1]A Avdic, A Lugstein, M Wu, B Gollas, I Pobelov, T Wandlowski, K Leonhardt, G Denuault, E Bertagnolli "Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM–SECM", Nanotechnology 22 (2011) 145306.[2]W. Smirnov, A. Kriele, R. Hoffmann, E. Sillero, J. Hees, O. A. Williams, N. Yang, C. Kranz, C. E. Nebel, Diamond-Modified AFM Probes: From Diamond Nanowires to Atomic Force Microscopy-Integrated Boron-Doped Diamond Electrodes”, Anal. Chem., 2011 in press, DOI: 10.1021/ac200659e.
3:45 PM - N11.4
Combined Photo- and Thermionic Electron Emission from Nitrogen Doped Diamond Films on Doped Silicon Substrates.
Tianyin Sun 1 , Franz Koeck 1 , Robert Nemanich 1
1 Department of Physics, Arizona State University, Tempe, Arizona, United States
Show AbstractEnergy conversion through electron emission from low work function diamond surfaces has been proposed by our group. It has been demonstrated that a low effective work function can be achieved on nanocrystalline diamond films through nitrogen doping and hydrogen termination. Nanocrystalline diamond films on metal substrates have shown low temperature thermionic emission and visible light photo-emission. Recently Schwede et al. reported photon-enhanced thermionic emission (PETE) on GaN [1], and suggested that a bi-layer structure can further increase the PETE efficiency. The proposed structure has a narrow band gap “absorber” and a wide band gap “emitter” with surface negative electron affinity. In this work we present the results of electron emission from a bi-layer structure composed of a phosphorus-doped Si substrate (absorber) and a nitrogen-doped diamond film (emitter). The results are compared with similar diamond films grown on metal substrate. The films have been illuminated with light from 340nm to 600nm by employing a Xe arc lamp and band pass filters, and both the spectra of the emitted electrons and the photocurrent have been recorded as a function of temperature from ambient to ~360°C. On the bi-layer structure, photon illumination can significantly increase the electron emission in a modest temperature regime (between ~220°C and 270°C), yet the photocurrent decreases when sample temperature is further increased and thermionic emission becomes dominant. These results appear to be consistent with the PETE process which combines thermal and photo excitation [1], and indicate application in combined solar/thermal energy conversion devices.Supported by the Office of Naval Research.[1] J.W. Schwede et al. Photon-enhanced thermionic emission for solar concentrator systems. Nat. Mater. 9, 762-767 (2010)
4:00 PM - N11.5
Effect of Transfer Doping on the Structure Formation of C60 Self-Assembly on Hydrogenated Diamond C(100)-(2x1):H.
Markus Nimmrich 1 , Markus Kittelmann 1 , Philipp Rahe 1 , Wolfgang Harneit 1 , Angelika Kuehnle 1
1 Department of Physical Chemistry, University of Mainz, Mainz Germany
Show AbstractThe well-controlled adsorption of fullerenes on (modified) diamond surfaces is of great importance with respect to a variety of tasks in surface science. The future possibilities range from the implementation of a fullerene-based electron spin quantum computer [1,2] to the realisation of semiconductor devices based on diamond [3], utilising the transfer doping capability of fullerenes [4]. All these applications require a thorough understanding of the process of fullerene adsorption on the respective surface. This includes detailed knowledge of structures formed by self-assembly, underlying diffusion processes and the nature of the binding forces present. An ideal tool to gain this essential insight is non-contact atomic force microscopy (NC-AFM) in UHV, since it allows for real-space imaging of the adsorption behaviour of C
60 fullerenes on both, conducting as well as insulating diamond surfaces [5]. Moreover, NC-AFM can be utilised for the specific manipulation of single molecules, enabling well-controlled surface modelling on the atomic scale.
In this contribution, we present an adsorption study characteristics of C60 fullerenes on both, the hydrogenated diamond C(100)-(2x1):H surface and the bare diamond C(100)-(2x1) surface under UHV-conditions using NC-AFM.
On the hydrogenated diamond surface, the C60 molecules self-assemble to irregular shaped islands with the internal structure being hexagonal. The rectangular structure of the underlying terraces is reflected in the islands by the formation of two domains. Both, island size and height can be increased significantly by moderate annealing. The rather weak binding to the substrate can also be exploited by manipulating island height and shape in a well-controlled manner utilising tip-sample interactions. Since the possibility of transfer doping is what fundamentally distinguishes C(100)-(2x1):H from structurally similar surfaces like Si(100)(2x1):H, these results are evaluated with particular attention paid to the contribution of transfer doping to structure formation.
The bare diamond surface is chemically entirely different to the hydrogenated surface since it consists of π-bonded carbon dimers, which are expected to strongly interact with the large conjugated systems of C60 molecules. This is confirmed in our NC-AFM images, which display no signs of molecular diffusion but illustrate a strong covalent bonding between C60 and C(100)-(2x1).
[1] W. Harneit, Phys.Rev. A 65, (2002)032322
[2] J.J.L. Morton et al., Nature Phys. 2, (2006)40
[3] M. Itoh and H. Kawarada, Jpn. J. Appl. Phys. 34, (1995)4677
[4] P. Strobel et al., Nature 430, (2004)439
[5] M. Nimmrich et al., Phys.Rev. B 81, (2010) 201403
N12: Poster Session - Diamond
Session Chairs
Thursday AM, December 01, 2011
Exhibition Hall C (Hynes)
9:00 PM - N12.10
Field Emission Mechanism of H-Terminated N-Type Diamond NEA Surface.
Takatoshi Yamada 1 , Masataka Hasegawa 1 , Christoph Nebel 2 , Yuki Kudo 3 , Tomoaki Masuzawa 3 , Ken Okano 3
1 , National Institute of Advanced Industrial Science and Technology, Tsukuba Japan, 2 , Fraunhofer Institute for Applied Solid State Physics, Freiburg Germany, 3 , International Christian University, Mitaka Japan
Show AbstractDiamond is expected to be one of the promising materials for field emission devices, since diamond surface has negative or small positive electron affinity. H-terminated n-type diamond NEA surface is the best solution for low voltage driven field emitters. However, a higher electric field was necessary to emit electrons from n-type diamond NEA surface [1]. It was speculated that an internal barrier existed at n-type diamond NEA limit field emission properties [2]. Here, we estimated the effective electric field on n-type diamond NEA surface from results of field emission characteristics and evaluated the effective emission barrier height using ultra-violet photoelectron spectroscopy (UPS) characterizations. n-type diamond films were homoepitaxialy grown on (111) oriented high temperature high pressure Ib synthetic diamonds using micro-wave plasma chemical vapor deposition (CVD). In order to form NEA, H-plasma treatment was carried out.Diamonds were mounted as cathodes in high vacuum system and the emission current vs anode voltage (I-V) characteristics as a function of anode-cathode distances were measured. W needle was used for an anode electrode. UPS measurements was carried out to evaluate electron affinity and to determine the surface Fermi level. He I (21.2 eV) was used to excite.Threshold voltage vs distance (Vth-d) characteristics, obtained from the I-V characteristics, showed almost linear relationship between turn-on voltage and distance. Slope of this Vth-d characteristics indicates an average electric field in vacuum [3]. By taking field enhancement factor of 10 into account [4], the effective electric field (Eeff) at surface was calculated to be 5.4 x 106 V/cm. Schottkey barrier lowering model was applied to estimate the internal barrier height. Using the calculated effective electric field (Eeff), the internal barrier height was estimated to be 3.3 eV. This was almost same as the energy difference between bulk and surface conduction band minimum obtained from UPS. From the results, it was considered that the obtained higher filed is necessary to lower the internal barrier for the electron emission. In order to utilize NEA on n-type diamond surface for the low voltage driven field emitters, the reduction of the internal barrier height is the key technique.The present work is financially supported by the Support Program for Private Universities S0801012) and 10 Grants-in-Aid for Scientific Research (19205026), both from the Ministry of Education, Culture, Sports, Science & Technology, Japan. [1]T.Yamada et al., J. Vac. Sci. Technol. B 24 (2006) 967-970.[2]T. Yamada et al. Appl. Phys. Lett. 88 (2006) 212114.[3]T. Yamada et al., Appl. Phys. Lett. 76 (2000) 1297-1299.[4]T. Yamada et al., Appl. Phys. Lett. 87 (2005) 234107.
9:00 PM - N12.11
The Influence of Boron Doping in the Growth of Ultra/Nanocrystalline Diamond Films.
Fernando Souza 1 , Adriana Azevedo 1 , Maurício Baldan 1 , Neidenei Ferreira 1
1 LAS/CTE, IInstuto Nacional de Pesquisas Espaciais, São José dos Campos, São Paulo, Brazil
Show AbstractDiamond nanocrystal is a topic of considerable interest in the scientific community, as properties of these systems are expected to retain a large extent of singular characteristics concerning polycrystalline diamond films. Boron is the most successful and widely used acceptor in diamond; and the doping can be achieved by adding substances as diborane, trimethyl borane and boron trioxide. In this work boron-doped nanocrystalline diamond (BDND) films were grown on silicon substrates by hot filament chemical vapor deposition in Ar/H2/CH4 gas mixtures. In the current study, the transition from ultrananocrystalline to nanocrystalline diamond films is clearly showed by addition of boron dopant in the growth gas mixture. The films were grown in a hot filament chemical vapor deposition reactor. The doping process consisted of an additional H2 line passing through a bubbler containing B2O6 dissolved in methanol with different B/C ratios. Five sample sets were obtained with doping levels of 2,000, 5,000, 10,000, 20,000 and 30,000 ppm for growth time of 16 h. The morphology and structure of these films have markedly different properties. The films were characterized with scanning electron microscopy in both top view and cross section showing the transition from ultrananocrystalline growth (re-nucleation process) to a columnar structure of NCD films. The acceptor densities, evaluated from Raman spectra, varied from 1020 to 1021 B.cm−3 as the doping level increased. The grain size and the relative intensity for the (111)/(220) peaks were obtained from X-ray diffraction patterns of the films. The diamond average grain size increased from 10 to 35 nm for films with 2,000 and 30,000 ppm B/C, respectively. Also, the preferential orientation changed from (110) to (111) as the boron doping level increased. Finally, Fourier transform infrared spectroscopy (FTIR)) provided important information about the film surfaces that have predominantly C-Hx and C=O bonds. The results demonstrated the singular properties of these films for different applications.
9:00 PM - N12.12
Anodic and Cathodic Pre-Treatment Effects on BDD Surface to Deposit Copper Nanoparticulas Applied to Nitrate Detection.
Laura Santos 1 , Jorge Matsushima 1 , Maria Cristina Forti 2 , Maurício Baldan 1 , Neidenei Ferreira 1
1 LAS/CTE, IInstuto Nacional de Pesquisas Espaciais, São José dos Campos, São Paulo, Brazil, 2 Centro de Ciências do Sistema Terrestre, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, São Paulo, Brazil
Show AbstractNitrate (NO3-) occurs naturally in waters not only because it is found in a large range of natural processes but also as a component of the nitrogen cycle. Nowadays, nitrate represents a critical issue for fresh water contamination as well as coastal waters due to poor sanitation and limited waste water treatments. Moreover, the use of nitrogen-based compounds for a wide number of applications, such as in agriculture as an integral part of fertilizers and insecticides, in chemical synthesis as precursors of a large variety of chemicals, and in the food industry as preservers, savoring, and disinfectants corroborates to increase the contamination problem. So, the development of new materials to apply for quantitative analysis represents a topic of considerable interest. Boron doped diamond (BDD) electrode appears as an alternative solid material with singular electrochemical properties to nitrate reduction applications. BDD films were grown utilizing hot filament-assisted chemical vapor deposition (HFCVD) technique at 1050 K from 1.0% vol. CH4 in H2/CH4 mixture at a total pressure of 6.5 103 Pa. Boron was obtained from H2 forced to pass through a bubbler containing B2O3 dissolved in methanol. The B/C ratio used corresponds to the acceptor densities of around 1021 cm-3 estimated from Raman measurements. The influence of anodic and cathodic pre-treatment on BDD surface for copper (Cu) nanoparticles electrodeposition was studied to assess Cu nanoparticle consolidation on BDD electrode. These Cu modified BDD electrodes were applied to study the nitrate electrochemical reduction process. The obtained results showed that the BDD surface cathodically treated presented high Cu nanoparticle density as well as even distribution on the electrode surface after the electrodeposition process. For samples anodically treated the electrodeposited Cu was dispersed with lower particle density. This behavior was attributed to a high electrode conductivity imposed by the cathodic pre-treatment leading to an increase in the BDD surface hydrogenation that was confirmed by the contact angle measurements. Therefore, one can conclude that for electrochemical nitrate reduction the anodically treated BDD has a best reproducibility. This response is attributed to the Cu nanoparticle consolidation on BDD electrode due to the oxygen surface terminations induced by the anodic pretreatment.
9:00 PM - N12.13
Comparison of Electrochemical Biosensor Based on BDD Electrode and Au Electrode with Pt-Dispersed Polyaniline Composites.
Min-Jung Song 1 , Jong-Hoon Kim 1 , Seung-Koo Lee 1 , Dae-Soon Lim 1
1 , Korea University, Seoul Korea (the Republic of)
Show AbstractAn electrochemical biosensor with low detection limit was developed using a Pt-dispersed polyaniline (PANI) composites based on a boron-doped diamond thin film electrode. For identifying performances of this biosensor, glucose was used as a sample and the results were compared with those of a gold electrode. A highly conductive boron-doped diamond thin film (BDD) was prepared by chemical vapor deposition, and its morphology was characterized by scanning electron microscopy and transmission electron microscopy. PANI nanorods were synthesized directly on a gold electrode and a BDD electrode, and high-density Pt nanoparticles were dispersed on the PANI nanorods by electrochemical deposition. Although a sensitivity of the modified BDD electrode was a little lower than that of the Au electrode, the modified BDD electrode shows a significantly larger linear range and a much lower detection limit than the modified Au electrode. It strongly suggests that the BDD might be a superior choice for the analysis of low concentrations of analytes as compared to conventional electrodes.
9:00 PM - N12.14
The UNCD Film Synthesis on the Micro-Patterned SiO2/Si Substrate by DC-PACVD.
Hak-Joo Lee 1 2 , Jung-Min Cho 1 , Hyeongtag Jeon 2 , Wook-Seong Lee 1
1 Electronic Materials Center, Korea Institute of Science and Technology, Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Hanyang University, Seoul Korea (the Republic of)
Show AbstractIt is challenging to achieve a uniform ultra nanocrystalline diamond (UNCD) coating on the micro-patterned SiO2 layer on Si wafer where the Si is exposed in the trench, since the diamond nucleation greatly differs on SiO2 and Si; a uniform layer formation of UNCD on such patterned surface is important for MEMS/NEMS applications. In the present study, the nucleation and growth of UNCD film on such surfaces were investigated under the direct current plasma assisted chemical vapor deposition (DC-PACVD) environment. The 300 nm-thick SiO2 layer was formed on the Si wafer; subsequently 5 μm-wide trench was formed using lithographic technique to remove the SiO2 and consequently expose the underlying Si. Such micro-patterned wafer was used as the substrate; it was ultrasonically seeded using methanol suspension of the nano diamond powder with subsequent ultrasonic cleaning.The substrate was exposed to the UNCD deposition by DC-PACVD process for 15-150 min using methane-hydrogen precursor gas mixture. The chamber pressure, methane content, total gas flow rate, cathode and substrate temperature, discharge voltage and current were 100 Torr, 150 sccm, 850 °C, 750 °C, 480 V and 25 A. The microstructure and crystallinity of the coated sample were analyzed by HRSEM, XRD, Raman spectroscopy and NEXAFS. The diamond nucleation and growth on the patterned substrate was strongly dependent on the seed powder type as well as on the surface treatment using hydrogen plasma prior to seeding. Uniform UNCD layer coverage on the micro-patterned surface was enabled through an optimized process, of which the detail will be discussed.AcknowledgementsThis work was supported by a grant (code No.: 2011K000174) from the ‘Center for Nanostructured Materials and Technology’ under ‘21st Century Frontier R&D Programs’ of the Ministry of Education, Science and Technology, Republic of Korea. This work was also supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Korea.Corresponding Author: W.-S. Lee, Tel: +82-2-958-5497, Fax: +82-2-958-5509, E-mail:
[email protected]9:00 PM - N12.15
The Optimization of Nanocrystalline Diamond Film for the Waveguide Sensor with ATR Geometry.
Hak-Joo Lee 1 2 , Jung-Min Cho 1 , Kyeong-Seok Lee 1 , Hyeongtag Jeon 2 , Wook-Seong Lee 1
1 Electronic Materials Center, Korea Institute of Science and Technology, Seoul Korea (the Republic of), 2 Department of Materials Science and Engineering, Hanyang University, Seoul Korea (the Republic of)
Show AbstractATR (Attenuated Total Reflection)-type waveguide sensor is an important type of optical sensor which enables any molecular sensing, for a wide variety of applications. In this type of sensor, the multiple reflection element, i.e. the waveguide layer material, is critical for its performance.[1] Although the diamond is the most promising among such materials, the relevant study is in its infant stage. In the present study, we have investigated the optimization of the optical properties of nanocrystalline diamond (NCD) film waveguide layer, for application to the ATR-type sensor. The NCD film was synthesized on the sapphire substrate using Hot-filament CVD technique. The polished sapphire substrate was 1.76 in refractive index and 0.5 mm in thickness; it was pre-coated with 500 nm-thick SiO2 film as a low-index coupling layer, on the side where the NCD layer was to be coated. The substrate was ultrasonically seeded with nano diamond powder seeding suspension. The chamber pressure and precursor gas composition were 7.5 Torr and 0.5/5% CH4 in H2. Filament–substrate distance was varied from 10 mm to 40 mm with substrate and filament temperature maintained at 700/800 °C and 2100 °C, respectively. The structure of the synthesized NCD film was analyzed by SEM, XRD, and TEM; its optical properties were studied by UV–VIS spectrometer in the 250–1100 nm wavelength range; the absorption coefficient was determined from the measure reflectance and transmittance. The waveguiding properties of the NCD layer were studied by prism coupler technique; the guided modes for p- and s-wave were characterized with varying incident angle using 632.8 nm laser. The NCD waveguide exhibiting an excellent waveguiding performance was enabled via optimization of the microstructure, of which the detail will be discussed in the presentation.Reference[1] Lars Osterlund, Per Ola Andersson, Mikael Karlesson, F Nikolajeff (2011) US Patent US 2011/0090484 A1.AcknowledgementsThis work was supported by a grant (code No.: 2011K000174) from the ‘Center for Nanostructured Materials and Technology’ under ‘21st Century Frontier R&D Programs’ of the Ministry of Education, Science and Technology, Republic of Korea. This work was also supported by an institutional program grant (2E22123) from Korea Institute of Science and Technology.Corresponding Author: W.-S. Lee, Tel: +82-2-958-5497, Fax: +82-2-958-5509, E-mail:
[email protected].
9:00 PM - N12.16
Photovoltaic Characteristics of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Under Illumination of UV Light.
Shinya Ohmagari 1 , Yuki Katamune 1 , Tsuyoshi Yoshitake 1
1 Department of Applied Science for Electronics and Materials, Kyushu Univ., Kasuga, Fukuoka, Japan
Show AbstractUltrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films, wherein diamond crystallites with diameters of less than 10 nm are embedded in an a-C:H matrix, have great potential for the application to optoelectronics devices owing to the unique characteristics such as large absorption coefficients of 105 - 106 cm-1 in the photon energy range between 3 and 6 eV. However, there have been a few researches on it. Recently, we have fabricated heterojunction diodes consist of p-type UNCD/a-C:H films and n-type Si [1]. In this study, the photodetection characteristics of the diodes were evaluated.Experimentally, 3 at.% boron-doped p-type UNCD/a-C:H films were deposited on n-type Si substrates by pulsed laser ablation with a boron-blended graphite target. The detailed preparation procedures have been described in our previous paper [2]. Pd and Al Ohmic electrodes were deposited on the UNCD/a-C:H and Si substrate surfaces, respectively.The current-voltage characteristics of the diodes in the dark showed a typical rectification action with a rectification ratio greater than 102 [1]. A photoresponse were apparently observed for 254-nm monochromatic UV illumination at room temperature. The external quantum efficiency was estimated to be 71% at a reverse voltage of -5V. The photoresponse spectrum showed the contribution of UNCD crystallites to the photovoltaic effect. We experimentally proved that UNCD/a-C:H is a promising semiconducting material applicable to optoelectronic devices. Further discussions will be made in the conference.[1] S. Ohmagari et al., Jpn. J. Appl. Phys. (2011) in press.[2] S. Ohmagari et al., Jpn. J. Appl. Phys. 49 (2010) 031302.[3] S. Ohmagari et al., Diamond Relat. Mater. 19 (2010) pp. 911-913.
9:00 PM - N12.17
Enhanced Growth of Diamond Crystallites in Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films by Boron-Doping.
Shinya Ohmagari 1 , Yuki Katamune 1 , Aki Tominaga 1 , Tsuyoshi Yoshitake 1
1 Department of Applied Science for Electronics and Materials, Kyushu Univ., Kasuga, Fukuoka, Japan
Show AbstractUltrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) films, wherein diamond crystallites with diameters of less than 10 nm are embedded in a hydrogenated amorphous carbon matrix, are new candidate materials for applications to micro-electro mechanical systems (MEMS), hard coatings, and optoelectronics devices. Since the UNCD/a-C:H films are formed with successive diamond nucleation process during film growth, the diamond growth of UNCD crystallites appears to be sensitively influenced by the coexistence of foreign elements during the formation. Boron is an ideal p-type dopant for diamond. For the film growth, boron-doping improves the structural perfection of diamond crystallites [1]. In addition, whereas the crystallite size is slightly decreased with an increase in the boron content, the nucleation density is enhanced significantly. While, in contrast, the boron-doping effects on the formation of UNCD/a-C:H films have rarely been studied thus far. We have realized the formation of UNCD/a-C:H films, wherein a large number of UNCD crystallites with diameter of 5 nm are embedded in an a-C:H matrix, by pulsed laser deposition (PLD) [2]. In this study, UNCD/a-C:H films were prepared by PLD with boron-doped graphite targets and the effects of the boron-doping on the UNCD crystallite formation were structurally investigated.The crystallite size estimated from XRD was increased from 5 to 23 nm and the lattice constant approached to that of bulk diamond with an increase in the boron content up to 13 at.%. This might indicate that the boron-doping enhances the UNCD crystallite growth accompanied with relaxing of diamond lattice expansion. The sp3/(sp3 + sp2) ratio estimated from the X-ray photoemission spectra was enhanced by the boron-doping, which might be predominantly attributable to the enlarged crystallites. Near-edge x-ray absorption fine structure and Fourier transform infrared spectroscopy measurements revealed that boron atoms preferentially incorporated into grain boundaries. It was found that boron atoms enhance the UNCD crystallite growth posterior to the nucleation without their remaining in diamond lattices. The details will be reported at the conference.[1] X. H. Wang, G.-H. M. Ma, Wei Zhu, J. T. Glass, L. Bergman, K. F. Turner, and R. J. Nemanich, Diamond Relat. Mater. 1 (1992) 828.[2] T. Yoshitake, A. Nagano, M. Itakura, N. Kuwano, T. Hara, and K. Nagayama, Jpn. J. Appl. Phys. 46 (2007) L936.
9:00 PM - N12.18
Enhanced Wettability of Nanocrystalline Diamond Films for Biocoating Applications.
Jason Yang 1 , Kungen Teii 1
1 Applied Science for Electronics and Materials, Kyushu University, Kasuga Japan
Show Abstract Biocompatibility is a major issue in the research and development of advanced medical devices. In the current standard of metal biomaterials, medical grade stainless steel, cobalt and titanium alloy are used. Although these materials have high hardness and wear, they are lack of biocompatibility compared to carbon-based materials. Diamond and diamond-like carbon films have attracted enormous attention in the development of biocoating for medical devices not only for its high hardness and high chemical inertness, but also for its excellent biocompatibility. For a biocompatible surface, wettability is one of the important factors that governs the stability and reactivity of the system. Studies have shown that nanocrystalline diamond (NCD) films exhibit good biocompatibility and high thrombosis. Presented in this paper is the study of wettability enhancement of NCD films. The films were prepared on Si by microwave plasma-enhanced chemical vapor deposition using Ar-rich/N2/CH4 and Ar-rich/H2/CH4 mixtures, and further treated by microwave hydrogen and oxygen plasma exposure separately. The hydrogen plasma treatment had small effect on the surface roughness, while the oxygen plasma treatment formed fine protrusions on the film surface. Results have shown that the wettability of the hydrogen plasma treated NCD film was nearly constant or little improvement as the polar component of the apparent surface free energy was close to the as-deposit NCD film of 0.4 mJ/m2. In contrast, the wettability of the oxygen plasma treated NCD film was improved dramatically such that the contact angle was reduced from 92 and 4.7 degree to almost zero for water and 1-bromonaphthalene, respectively, and the polar component increased significantly to 34 mJ/m2. The low contact angle suggests that the film is considerably a cell adhesive friendly surface, which is essential in maintaining multicellular structure, and thus making it a favorable wetting surface for biological and biomedical applications.
9:00 PM - N12.19
Fabrication of Microplasma Arrays from CVD Diamond.
Monika Zeleznik 1 , Paul May 1 , Neil Fox 1 , Judy Hart 1 , Mark Bowden 2 , Sebastien Mitea 2 , Robert Stevens 3 , Chantal Fowler 3
1 School of Chemistry, University of Bristol, Bristol United Kingdom, 2 Department of Physics & Astronomy, Open University, Milton Keynes United Kingdom, 3 Micro and Nanotechnology Technology Centre, Rutherford-Appleton Laboratory, Harwell Oxford United Kingdom
Show AbstractMicroplasmas are small electrical discharges with dimensions of less than 1 mm. The most common and most efficient architecture used to create microplasmas is a hollow-cathode discharge device. For cavities < 100 µm operation in atmospheric pressure has been demonstrated. We present the results from the world's first diamond microplasma device, made entirely out of doped (electrodes) and undoped (dielectric) diamond. This allows for easy fabrication and carries several other benefits directly connected to the properties of diamond, such as increased lifetime due to robustness of diamond, or lower voltage needed to strike the microplasma than with other materials. This poster will concentrate on the procedures used to fabricate these interesting devices.
9:00 PM - N12.2
Fabrication of Diamond Nanopit Arrays by Room-Temperature Curing Nanoimprint Lithography Using Glass-like Carbon Molds.
Shuji Kiyohara 1 , Chigaya Itoh 1 , Ippei Ishikawa 1 , Yoshio Taguchi 2 , Yoshinari Sugiyama 2 , Yukiko Omata 2 , Yuichi Kurashima 3 , Hirofumi Takikawa 4
1 Electric and Control System Engineering Course, Maizuru National College of Technology, Maizuru, Kyoto Japan, 2 Application and Technical Section, ELIONIX INC., Hachioji, Tokyo Japan, 3 Department of Mechanical Systems Engineering, University of Yamanashi, Kofu, Yamanashi Japan, 4 Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi Japan
Show AbstractThe diamond exhibits unique properties such as high hardness, high thermal conductivity, wide band-gap and chemical stability, and so it is expected to have various applications. For example, it can be used emitter for flat panel display, micro-gear for micro-machine, semiconductor devices and biosensors. Therefore, the nanopatterning technique for a diamond is essential to the fabrication of functional micro/nano devices. We had already investigated the nanopatterning of chemical vapor deposited (CVD) diamond films in room-temperature curing nanoimprint lithography (RTC-NIL), using diamond molds. The diamond molds had been fabricated with electron cyclotron resonance (ECR) oxygen ion beam etching using polysiloxane [-R_2SiO-]n with the electron beam (EB) lithography technology that we developed. However, we could not fabricate diamond nanopit arrays in high accuracy because the maximum etching selectivity of polysiloxane film against diamond film was as low as 4.7. To overcome this problem, we have proposed the use of glass-like carbon (GC), as mold material, which has excellent properties similar to those of the diamond, and the maximum etching selectivity of polysiloxane film against GC was 27. We have investigated the fabrication of diamond nano-pit arrays by RTC-NIL using GC mold, as an application to the emitter.A polished GC (10 mm-square, 3.2 mm-thickness, 1.6 nm-arithmetic average roughness ) (Hitachi Chemical Co., Ltd., Japan, PXG-35) was used as a mold material. The polysiloxane (Hitachi Chemical Co., Ltd., Japan, HSG-R7-13) is in the state of sticky liquid at room temperature and stable in air exhibits a negative-exposure characteristics. Therefore, the polysiloxane was used EB resist and oxide mask material in EB lithography, and also used as RTC-imprint resist material. We have fabricated the GC mold of nano-dot with 500 nm diameter which have a height of 500 nm. We carried out the RTC-NIL process using the GC mold under the following optimum conditions: time from spin-coating to imprint of 1 min, imprinting pressure of 0.5 MPa and imprinting time of 5 min. Then we have processed the GC with an ECR oxygen ion shower apparatus (ELIONIX Co., Japan, EIS-200ER). We have observed the fabricated diamond nano pattern with a scanning electron microscope having four secondary electron detectors (ELIONIX Co., Japan, ERA-8900FE).We have fabricated diamond nanopit arrays which are 250 nm in depth, and 500 nm in diameter. The diameter of diamond nanopit pattern was in good agreement with that of the GC mold. Moreover, the depth of the diamond nanopit pattern fabricated by RTC-NIL using of GC mold was three times than that using the diamond mold.
9:00 PM - N12.20
Ink-Jet Deposition of Nanodiamond Seeds for Nanocrystalline Diamond Films Patterning.
Jan Vlcek 1 , Frantisek Fendrych 2 , Martin Vrnata 1 , Premysl Fitl 1 , Dusan Kopecky 1 , Jitka Skodova 1
1 , Institute of Chemical Technology, Department of Physics and Measurements, Prague Czechia, 2 , Institute of Physics AS CR, Prague Czechia
Show AbstractThe patterning of nanodiamond (ND) thin films is one of the key issues for fabrication of many electronic and mechanical devices. Several methods of patterning of ND films have been used, based mainly on Reactive Ion Etching (RIE) or lithographically patterned seeding. However most of techniques have no such trivial processing and require complex devices.This paper concerns a method how to fabricate micro-patterns by an Ink-jet deposition of ND seed onto the substrate surface for conventional nanocrystalline diamond (NCD) growth and optimization towards the highest possible lateral resolution. Ink-jet deposition is very simple processing, quick and inexpensive method of selective covering surfaces by ND seeds, but needs specific setup of conditions. The Ink-jet printing allows 1-D, 2-D as well as 3-D structure formation of ND. The aim of this work is study the seeding substrates for different parameters of the ND inks and conditions of the Ink-jet deposition. For 2-D Ink-jet deposition we used system consists of Microdrop dispenser head with inner nozzle diameter of 70 μm and micro-motion XYZ axis system GRAVOSTAR GV21 with enhanced step resolution of 250 nm. We studied different concentration of ND in the inks (0.2 - 2.0 % wt.), frequency of micro-drops producing (< 400 Hz). As a ND ink we have used OSAWA NDs with average size of 10 nm uniformly dispersed in water. Based on ink-jet deposition of simple ND structure and subsequent MW PECVD deposition of NCD film on silicon and fused silica substrates we optimized parameters to reach the highest resolution as possible. We present AFM and SEM characterization to investigation of lateral resolution and surface roughness. Raman diagnostics was carried out for diamond quality investigation.
9:00 PM - N12.21
Reactive Flow Simulation in Diamond Growth by Direct Simulation Monte Carlo.
Edson Fumachi 1 , João Amstalden 2 , Neidenei Ferreira 1 , Mauricio Baldan 1
1 , INPE, São José dos Campos, São Paulo, Brazil, 2 , Bosh Group, Campinas, São Paulo, Brazil
Show AbstractDiamond thin films are particularly suited for a wide range of industrial applications due to the superior properties of diamond. The chemical vapour deposition (CVD) is a widely employed manufacturing technique for coatings a wide range of functional thin films. However, the main drawback of current diamond CVD processes are the lack of fundamental understanding of CVD phenomena, which severely limits current efforts of optimizing growth conditions. The major difficulty is due to the large number of complex competing mechanisms which occur in a very narrow layer near the substrate, thus making very difficult the direct probing of the involved phenomena. On the other hand, macroscopic modeling has contributed to a significant improvement to the current knowledge. However, their strong limitation is that they cannot simulate in detail the microstructure development during film growth. Thus, more suitable feature-scale simulation models are more appropriate for this purpose. In this work a reactive flow model has been developed to simulate the gas phase for diamond thin film growth in a hot filament chemical vapour deposition reactor (HFCVD) by direct simulation Monte Carlo (DSMC). The overall model, which is based on the original DSMC, allows the simulation of the chemical reactions in the HFCVD reactor. A reaction system model has been developed for simulation gas-phase reaction for a typical H2-CH4 mixture. The reliability of the model has been tested by comparing, the molar fraction as a function of the time and as a function of the substrate distance, with theoretical models and experiments.
9:00 PM - N12.22
Influence of Nano- and Micro-Crystalline Semiconductor Diamond Electrodes on the Electrochemical Responses Evaluated by Electrochemical Impedance Spectroscopy.
Eduardo Saito 1 , Adriana Azevedo 1 , Fernando Souza 1 , Neidenei Ferreira 1 , Mauricio Baldan 1
1 , INPE, São José dos Campos, São Paulo, Brazil
Show AbstractThe technological development of preparing doped diamond thin films has stimulated the investigation of the surface and electrochemical properties of this material. Polycrystalline Boron doped diamond (BDD) grown by hot filament chemical vapor deposition (HFCVD) presents great advantages such as wide potential window, chemical inertness, mechanical resistance, among others advantages. The films were grown under different boron concentrations in the feeding gas. The boron solution concentrations selected were 30,000 ppm for micro-crystalline film and three different concentrations for nano-crystalline 2,000, 20,000 and 30,000 ppm. The morphological microstructure was evaluated by Scanning Electron Microscopy and Atomic Force Microscopy (AFM). The structural characterization was performed by Raman spectroscopy and X-ray diffraction. The electrochemical impedance spectroscopy (EIS) and differential capacitance measurements were performed with potentiostatic control in a three electrode cell with a platinum mesh as a counter electrode. The EIS measurements were made in the frequency range of 2.0x104Hz to10-1Hz with the redox pair (10-3 ml-1 Ferro/Ferricyanide in a 1ml-1 KCl) and the differential capacitance measurements were taken in 0.5Mol l-1 solution. All measurements were conducted at room temperature. The present work evaluated the kinetic performance of the BDD films micro- and nano-crystalline for electrochemical applications. The main technique was the electrochemical impedance spectroscopy (EIS) to obtain the heterogeneous charge transfer constant (K0) from the charge transfer resistance obtained by fitting the equivalent electric circuit. The results showed a considerable reduction of grain size for the nano-crystalline diamond when compared with the micro-crystalline as a function of the doping level. The micro-crystalline diamond film doped with 30,000 ppm solution presented approximately the same donor concentration of the nano-crystalline doped with 2.000 ppm. The nano-crystalline BDD doped with 30,000 ppm showed a strong decrease in the charge transfer resistance when compared with the nano-crystalline BDD doped with 2,000 ppm. However, the donor concentration was about the same for both BDD films. The EIS technique identified an increase in the (K0) for the nano-crystalline BDD film with the highest doping level.
9:00 PM - N12.23
Systematic Studies of Ultrananocrystalline Diamond Films Grown by Bias-Enhanced Nucleation and Growth in Hydrogen-Rich Plasmas.
Jung-hyun Park 1 2 , Yueh-chieh Chu 1 3 , Chia-hao Tu 1 4 , Pablo Gurman 1 , Charudatta Phatak 1 , Yonhua Tzeng 3 , Ali Erdemir 5 , Junho Choi 5 6 , Orlando Auciello 1 2
1 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 2 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 3 Department of Electrical Engineering, National Cheng Kung University, Tainan Taiwan, 4 Department of Materials Science and Engineering, National Cheng Kung University, Tainan Taiwan, 5 Energy Systems, Argonne National Laboratory, Argonne, Illinois, United States, 6 Department of Mechanical Engineering, The University of Tokyo, Tokyo Japan
Show AbstractUltrananocrystalline diamond (UNCD) films were directly grown on Si substrates, using H2-rich/CH4 gas chemistry in a microwave plasma-enhanced chemical vapor (MPCVD) deposition system at low pressures. Four sets of UNCD films were grown at different total pressures in the range 21-25 mb, on Si substrates, using heat-assisted bias-enhanced nucleation and growth (BEN-BEG), where the nucleation layer is produced by exposing a clean Si surface to the H2-rich/CH4 plasma while applying a negative bias voltage to accelerate H+ and C+ ions from the plasma towards the substrate surface. The energetic C+ atom sub-plantation assisted by H+ ion bombardment leads to the formation of the UNCD nucleation layer, followed by film growth upon continuous substrate surface exposure to the H2-rich/CH4 plasma, while applying bias. The BEN-BEG grown UNCD films were examined by cross-sectional SEM and HRTEM to determine film thickness and morphology, and nanostructure of the film and the diamond-silicon interface, respectively. SEM and HRTEM imaging revealed that the BEN-BEG process results in a columnar growth at the interface with the Si surface followed by a smooth/dense film nanostructure in the remaining ~700 nm thick UNCD layer. The systematic study of the bias-enhanced grown UNCD films provided critical information to start understanding critical parameters of BEN-BEG UNCD films: a) grain nanostructure (3-5 nm) and film thickness (~ 700 nm /1 hr, ~ 4 times higher than the growth rate without bias); b) friction coefficient and hardness similar to UNCD films grown without bias. In conclusion, BEN-BEG provides a promising new processing route for growing UNCD films with properties relevant to the broad range of applications already identified for UNCD films grown without bias. The substantial technological advantage of the BEN-BEG process is that the cumbersome wet-chemical seeding process is eliminated, thus resulting in a more cost efficient all dry integrated nucleation-growth process.
9:00 PM - N12.24
Field Emission from Nanocrystalline Diamond/Carbon Nanowall Composite Films Deposited on Scratched Substrates.
Cheyueh Cheng 1 , Kungen Teii 1
1 , kyushu university, Kasuga Japan
Show AbstractCarbon nanowalls (CNWs) have two-dimensional networks of almost vertically aligned graphitic walls, and are expected for large-area field emitters due to the high aspect ratio and the high in-plane continuity of the wall structures. The emission turn-on field of CNWs is shown as below ~3 V/μm, which is as low as that of carbon nanotubes. However, the local field onto sharp edges of CNWs is not well enhanced due to electric field screening between the densely grown walls. Recently, we have shown the formation of nanocrystalline diamond/CNW composite films with a substrate scratching pretreatment using diamond powder, and the screening effect was suppressed by the widening of the wall spacing [1]. In this study, the condition of the scratching pretreatment is explored further to enhance the emission performance of CNWs. Two methods of substrate scratching treatment were used: 1-dimensional undulation and 2-dimensional ultrasonic vibration.Films were prepared from Ar/N2/CH4 mixtures by moderate-pressure (13.3 kPa) microwave plasma-enhanced chemical vapor deposition. The high concentration of Ar produced a high flux of C2 radicals, which enabled to deposit CNWs and amorphous carbon films containing diamond nanocrystals on scratched Si simultaneously.Both undulation and ultrasonic vibration methods resulted in the composite films. The overall spacing between the walls was widened by interception of the lateral wall continuity. The wall spacing depended upon the undulation times and the ultrasonic vibration period. The emission turn-on field could be reduced from around 3 V/μm for simple CNWs to around 1 V/μm for the composite films due to large field enhancement factors of 3000-4000, which is an indicative of suppression of the screening effect by increasing the wall spacing.[1] K. Teii and M. Nakashima, Appl. Phys. Lett. 96, 023112 (2010).
9:00 PM - N12.25
Synthesis and Characterization of Boron-Doped Diamond Coated 3D Copper Dendritic Architecture.
Seung-Koo Lee 1 , Huijun Sim 3 , Jong-Hoon Kim 1 , Min-Jung Song 2 , Min-Gun Jeong 1 , Eun-Ji Hwang 1 , Suk-In Hong 3 , Dae-Soon Lim 1
1 Materials Science and Engineering, Korea university, Seoul Korea (the Republic of), 3 Chemical and Biological Engineering, Korea University, Seoul Korea (the Republic of), 2 Center for Advanced Device Materials, Korea University, Seoul Korea (the Republic of)
Show AbstractBoron-doped diamond coated 3D copper dendritic architecture was fabricated on copper foil using morphosynthesis and electrostatic self-assembly of ultra-dispersed nanodiamond particles. First, the copper architecture was synthesized on copper foil which was immersed in 9 M formamide auqeous solution (40 wt% formamide in D.I. water) for 10 days. Electrostatic self-assembly of nanodiamond (ESAND) seeding method was performed as pre-treatment for diamond growth on copper architecture. To disperse nanodiamond particles, the solution which is mixed with initial agglomerated nanodiamond particles, anionic PSS (poly sodium 4-styrene sulfonate, Mw: 70,000) and D.I. water was attritionally milled with zirconium oxide beads of 0.3 mm at 1000 rpm for 6 hrs. During this process, the size of agglomerated nanodiamond particles is diminished to a size of about 20 nm. Also, dispersed nanodiamond particles were coated by anionic PSS. On the other hand, 3D copper architecture grown substrate was immersed in the cationic PDDA (poly diallyldimethyl ammonium chloride, Mw: 400,000 ~ 500,000) aqueous solution for 20 minutes. After rinsing and drying process, the copper architecture grown substrate was coated by cationic PDDA monolayer. Finally, nanodiamond coated copper architecture was successfully fabricated by dipping the PDDA coated substrate in the PSS coated nanodiamond suspension. Boron doped diamond was deposited by hot-filament chemical vapor deposition. The morphology of synthesized structure was examined by high resolution scanning electron microscopy (Hitach S-4800) and the bonding status of the diamond was analyzed by RAMAN spectroscopy with Ar-ion laser of 514 nm (Horiba Jobin Yvon T64000).
9:00 PM - N12.27
Shaping of Diamonds in 1D Nanostructures and Strategies for Fabrication of All-Diamond Microcomponents.
Maria Letizia Terranova 1 , Francesco Toschi 1 , Valeria Guglielmotti 1 , Ilaria Cianchetta 1 , Emanuela Tamburri 1 , Silvia Orlanducci 1 , Marco Rossi 2 , Vito Sessa 1
1 Dip. di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Roma Italy, 2 Dip. di Scienze di Base e Applicate per l’Ingegneria, Universita` degli Studi di Roma ‘‘Sapienza’’, Roma Italy
Show AbstractThe nanometric control of topography and fabrication of low-dimensional diamond materialsinto desired geometries are really challenging and complex tasks using currently available processes. The many new possibilities offered by recent advances in plasma source technologies are making it possible the setting of simplified and reliable methodologies able to modify at the nanoscale the features of diamond samples and to generate fascinating 1D diamond structures.We are currently developing procedures for the fabrication of elongated diamond 1D structures, such as nanorods, nanowhiskers and nanopillars by processes carried out in a specifically designed dual-mode plasma reactor, in which a radiofrequency can be applied to the substrate in the presence of the MW power. This technique connects the advantages of microwave discharge, such as homogeneity of plasma and high concentration of active species, with the ability to control ion energy and directionality by proper biasing of the substrate.The reaction pathways opened by the etching of hydrogen plasmas produced in the dual-mode MW-RF reactor are able to generate a variety of nanodiamond structures. Each of them differing from the others in the shape of the individual entities or in their mutual organization. Starting from different types of diamond samples, such as single-crystals, microcrystalline or nanocrystalline films and layers, the room temperature H-etching processes enable the reproducible fabrication of:- Arrays of vertically aligned diamond whiskers from close-packed flat layers formed by the self-assembling of detonation nanodiamond grains-- nanocolumns and nanopillars from single-crystal diamond plates- elongated cylindrical nanostructures from polycrystalline and nanocrystalline films- nanosized leaf-like structures protruding from individual well faceted diamond micrograins and by diamond grains aggregated in chainsThe functional (I/V, Field Emission) and structural (micro-Raman, RHEED) characterizations performed on a series of samples indicate that the etching process induced by H ions substantially lowers the resistivity of the material but does not modify the lattice parameters of the diamond phase. The proposed methodology represents a viable route for the realization of organised nanodiamond systems with shapes as close as possible to those required by applications in the field of micro-and nano-electronics.
9:00 PM - N12.29
Scalability for Liquid-Phase Synthesis to Deposit Low-k Carbon Nitride Films on Large-Scale Substrates.
Hideo Kiyota 1 , Mikiteru Higashi 2 , Masafumi Chiba 2
1 Department of Mechanical System Engineering, Tokai University, Kumamoto Japan, 2 Department of Materials Chemistry, Tokai University, Numazu Japan
Show AbstractReduction in device feature size for ultralarge-scale integration (ULSI) results in increased signal delay, power consumption, and cross-talk interference between device interconnections. Low-k materials with dielectric constant lower than 2 are required to replace silicon dioxide interlayer in multilevel interconnection of ULSI devices. Carbon nitride (CNx) has great potential for a low-k material used in modern ULSI technology because of its high resistivity and low dielectric constant. While the CNx films have been studied by using various deposition techniques, the liquid-phase synthesis to deposit the CNx film has been attempted as an alternative deposition technique by using organic liquid containing nitrogen. Previously, we have reported that continuous and uniform a-CNx films were deposited on Si substrates with dimensions of 20 x 40 mm2 when acrylonitrile (CH2CHCN) was used as the electrolyte. In this work, we have attempted the deposition of the CNx films on large-scale Si substrates to examine scalability for the liquid-phase synthesis to deposit the low-k interlayers. Deposition of the CNx film is carried out by application of a DC bias voltage to Si substrate immersed in liquid acrylonitrile. The Si substrates were mounted on both positive and negative electrodes to give a separation of 1 mm or less with parallel plate configuration. In this setup, typical deposition parameters are a bias voltage of 200 V, a current density of 1.0 mA/cm2, a liquid temperature of 70°C, and a deposition period of 60 min. Continuous and uniform films can be obtained on the Si substrates up to 100 mm in diameter by improving apparatus and deposition parameters. X-ray photoelectron spectra revealed that C, N, and O are major components of the deposited films. To evaluate the electrical properties of the deposited films, metal-insulator-semiconductor (MIS) structures are fabricated by evaporating Al electrodes onto the films. The deposited CNx films have a resistivity higher than 1011 Ωcm, which is measured using the electrodes in the MIS structures. The MIS capacitors exhibit three distinct regions of accumulation, depletion, and inversion in their capacitance - voltage (C-V) characteristics. The lowest dielectric constant k is determined to be lower than 3 through an analysis of the C-V results, indicating that the CNx film deposited in liquid acrylonitrile is a promising low-k material.The CNx films show uniform surface morphology, film thickness, composition, and electrical properties such as the dielectric constant across the deposited layers. In addition, a power consumption required to form the CNx films on Si wafer of 100 mm diameter was as low as 20 W; it is estimated to be ranging from 300 to 400 W for the deposition on 400 mm wafer. These results demonstrate the scalability for the liquid deposition process of the low-k insulating layer onto large-scale Si wafers used for ULSI production.
9:00 PM - N12.3
Spatially Controlling Neuronal Adhesion on CVD Diamond.
Paul May 1 , Ed Regan 2 , Alice Taylor 1 , James Uney 3 , Andrew Dick 3 , Joe McGeehan 2
1 School of Chemistry, University of Bristol, Bristol United Kingdom, 2 Department of Electrical and Electronic Engineering, University of Bristol, Bristol United Kingdom, 3 School of Clinical Sciences, University of Bristol, Bristol United Kingdom
Show AbstractThe mechanical and chemical properties of diamond coatings make them very suitable materials for improving the long-term performance of invasive electrode systems used in brain-computer interfaces (BCIs). We have performed in vitro testing to demonstrate methods for spatially directing neural cell growth and limiting the detrimental attachment of cells involved in the foreign-body response on boron-doped diamond. Laser micro-machining techniques were used to control neuronal adhesion and to modify inflammatory cell attachment. Laser micromachining was used to etch arrays of 10 connecting 100 µm × 1000 µm into the poly-L-lysine coated B-doped diamond. The patterns were visible under the optical microscope. Rat cortical neurons grew well across these substrates and neuritic outgrowth largely avoided crossing over the etched areas. This avoidance made the etched pattern visible upon staining of the cells and their processes. This work demonstrates that patterns etched into diamond to form a spatially defined substrate for organizing neural cell growth. Although preliminary, this work could have further applications in neural network research and nerve and brain repair scaffolds.
9:00 PM - N12.30
Preparation of Diamond Nanocrystallites in Powder by Using a Coaxial Arc Plasma Gun.
Aki Tominaga 1 , Yûtaro Ueda 1 , Kenji Hanada 1 , Tsuyoshi Yoshitake 1
1 , Kyushu University, Fukuoka Japan
Show AbstractPowdered diamond nanoparticles have been fabricated by detonation thus far. While carbon nanomaterials such as nanotubes and fullerenes have been fabricated by a variety of methods, it has been difficult for powdered nanocrystalline diamond to be prepared by methods except for the detonation method. We propose a novel method that enables us to fabricate diamond nanocrystallites in powder simply and compactly. We employ a coaxial arc plasma gun for the fabrication. As compared to conventional cathodic arc discharge, the coaxial arc plasma gun has a following distinctive feature. An anodic cylinder can bunch ions ejected from a cathodic graphite rod located inside the cylinder. Owing to this structure, a supersaturated condition with highly energetic ions can be realized [1], which results in the formation of diamond nanocrystallites. We report that powdered nanocrystalline diamond can briefly be fabricated by a coaxial arc plasma gun and the crystallite size is controllable from 1.6 to 15 nm by the discharge condition. A coaxial arc plasma gun (ULVAC APG-1000) equipped with a graphite target was operated at 5 Hz in vacuum and hydrogen atmospheres. The applied voltage and capacitance were changed in the ranges between 100-400 V and 360-1800 μF, respectively. The head of the gun was pointed at a quartz plate. Films that quickly and automatically exfoliated from the plate were gathered, and they were smashed into powder. The particles size was studied by powder X-ray diffraction (XRD) with 12 keV X-rays from synchrotron radiation at beamline 15 of the Kyushu Synchrotron Light Research Center/SAGA Light Source. The XRD pattern, which was transformed from the Debye-Scherrer rings recorded on an imaging plate, exhibited obvious peaks from diamond-111 and -220 while no peaks due to graphite. The crystallite size for the sample prepared at 100 V and 360 μF in vacuum was estimated to be 1.6 nm from the diffraction peaks, using Scherrer’s equation. The crystallite size was enhanced to be 15 nm for the sample prepared at 400 V and 1800 μF in a 53.3-Pa hydrogen atmosphere. The diamond crystallite is enlarged with an increase in the discharge power. In addition, the existence of hydrogen atmosphere during the discharge facilitates the growth of diamond crystallites. The details will be reported at the conference.[1] K. Hanada et al., Jpn. J. Appl. Phys. 49 (2010) 125503.
9:00 PM - N12.31
Cantilever Sensors for Threat Signatures: A Silicon-Nanodiamond Hybrid Device.
Joseph Welch 1 , Rezal Ahmad 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractCantilever sensors fall under the category of microelectromechanical systems (MEMS) that rely primarily on mechanical phenomena and involve the transduction of the mechanical energy for detection. The introduction of a chemically sensitive layer to a MEMS sensor can lead a measurable signal being generated in reaction to chemical stimuli. The extra loading on the cantilever caused by chemical adsorption causes deflection that can de detected by optical, piezoresistance, piezoelectric or capacitive methods. Cantilevers are typically made of single-crystal silicon. However, Si itself must be modified to offer suitable chemical properties for selective sensing applications.Diamond possesses properties favourable for chemical and biological sensing since as a material it can display exceptional chemical inertness and natural biocompatibility, whilst be readily chemically functionalized. However, the processing complexities of a diamond device currently limit the commercial prospects for such an approach. Here we propose a hybrid-solution, where inexpensive pre-fabricated Si cantilevers can be coated with nanodiamond particles offering the benefits of established Si technology with the properties of a diamond surface for sensing applications. It is shown that this hybrid device has a resonant frequency shifted down, compared to Si alone, by around 10% due to a higher spring constant. Exposure to 2,4-dinitrotoluene (as a safe analogue of the explosive TNT) leads to an easily observed decrease in resonant frequency. The mechanisms behind these observations are discussed and the promise for this form of hybrid cantilever structure for chemical sensors applications highlighted.
9:00 PM - N12.32
Neuronal Growth and Patterning on Diamond like Carbon Substrates.
Andrew Hopper 1 , Edward Regan 2 , Stephen Kelly 3 , Frederik Claeyssens 1
1 Materials Science and Engineering , University of Sheffield, Sheffield United Kingdom, 2 Henry Wellcome L.I.N.E., Clinical Sciences South Bristol, University of Bristol, Bristol United Kingdom, 3 New Jersey Neuroscience institute, JFK Medical Centre, Edison, New Jersey, United States
Show AbstractFor more than a decade diamond like carbon (DLC) has been explored as an attractive biocompatible material for coating implantable devices. These devices have been predominantly confined to vascular stents, cardiac valves and replacement joints. Work on these areas has led to significant advancement of the understanding of how DLC interacts with the mammalian immune and inflammatory systems. Modifying DLC by the addition of dopant materials, e.g. phosphorous or silicon, has been shown to modulate cell adhesion, cell activation and blood compatibility in vitro – making DLC a versatile substrate material. The aim of this study is to assess the suitability of modified DLC for the coating of neural implants. Neuronal adhesion and cytocompatibility of DLC substrates were assessed using primary central nervous system neurones and neuroblastoma cells. Additionally, methods of patterning other neural cells (both neurones and glia) are achieved by utilisation of the varying adhesion properties of the different DLC substrates, and by chemical surface modifications.We used DLC prepared by both by laser ablation [1] and electron beam writing on glass and silicon samples. These samples were further functionalised via oxidation [2] or photochemical attachment of surface functional groups. The neurocompatibility was tested via growth of both primary neurons (dissociated cortical neurons and dorsal root ganglion from E18 wistar rats) and neuroblastoma cell lines (NG108-15 cell line) on the substrates.MTT assays of cortical neural and neuroblastoma cell growth on DLC indicates that untreated DLC is a bioinert material, and that both doping with phosphorus, irradiating the material with UV light and chemical functionalisation with amino groups greatly improves neural adhesion on the DLC surfaces. These findings was exploited to produce neuronal patterns on the samples. Additionally we have studied patterned growth of dorsal root ganglion cells and human neural progenitor cells. Our data highlight that DLC is a modifiable substrate suitable for coating brain implants and we describe patterned growth of several neural cell types on this material. [1] E.M. Regan et al. (2008) Patterned growth of neuronal cells on modified diamond-like carbon substrates Biomaterials 29(17):2573-80. [2] E.M. Regan et al. (2010) Differential patterning of neuronal, glial and neural progenitor cells on phosphorus-doped and UV irradiated diamond-like carbon Biomaterials, 31 (2), 207-15
9:00 PM - N12.34
Effects of Crystallographic Planes on Focused Ion Beam Milled Patterns of Single Crystal Diamonds.
Rustin Golnabi 1 , Won Lee 1 , Deok-Yang Kim 1 , Glen Kowach 2
1 , Bergen County Academies, Hackensack, New Jersey, United States, 2 , The City College of New York, New York, New York, United States
Show AbstractFocused ion beam (FIB) milling of diamonds have been investigated in various ways to create desired structures on diamonds, but not much research has been reported on the effects of crystal orientation, i.e. (100), (110) and (111) of diamonds on FIB milling. In our previous work, it was noted that focused ion beam milling may develop preferred etched directions related to the crystal orientation of crystalline diamonds. In order to further investigate the phenomenon, a focused beam of 30 kV Ga+ ions was utilized to generate various pattern shapes (for example, square, triangle and circle, and etc) on different crystallographic planes of single crystalline diamonds. The morphology of milled patterns and the sputtering rates have been monitored with various ion currents to find any relationship between crystal orientations of a diamond and its impacts on FIB milled patterns. Our initial work showed that square beam patterns can generate hexagonal shaped trenches depending on the crystallographic planes of single crystalline diamonds.
9:00 PM - N12.35
Growth of Aluminum Doped Diamond for New p-Type Diamond.
Shinichiro Kurihara 1 , Ryo Nomura 1 , Ryusuke Kanomata 1 , Hidetoshi Tsuboi 1 , Daiki Ustunomiya 1 , Atsushi Hiraiwa 1 , Hiroshi Kawarada 1
1 nano science and nano engineering, Waseda university, Tokyo Japan
Show Abstract Diamond is promising materials for semiconductor industries and it is very important for realizing p-type and n-type diamond. A p-type diamond is obtained by boron doping and heavily doping is enabled. Our previous research shows superconductivity state was appeared where boron concentration was above 3×10
20cm
-3 [1]. Boron was considered the best acceptor for diamond. However, there is a serious problem that acceptor level is as deep as 0.37eV from the top of valence band [2]. In silicon carbide (SiC), the acceptor level of aluminum (Al) is located at 0.2eV which is shallower than that of boron (0.3eV) [3]. In diamond, the donor level of phosphorus (0.6eV) [4] is shallower than that of nitrogen (1.7eV). Considering these results, aluminum in diamond is expected to be shallower acceptor which realize room temperature carrier in the lightly doped p type layer which is inevitable for drift region in high power diode and FET. This lightly doped p-type layer at room temperature cannot realized by boron doping because of deep acceptor level, which is the most crucial problem for diamond electronic device. In this work, the properties of the aluminum doped diamond were evaluated. Introducing trimethyl aluminum, homoepitaxial diamond films were grown on HPHT Ib diamond(111) crystals by microwave plasma assisted chemical vapor deposition method (MPCVD). This MPCVD system has a spherical cavity which confines plasma in a limited area and was designed for decomposing dopant gas as low as possible to avoid clustering of aluminum atoms.Methane (CH4), hydrogen (H2) and trimethylaluminum (Al(CH3)3) was used as reactant gas. In case of phosphorus doping, low methane concentration and high temperature was essential for high quality P-doped diamond [4]. The condition was [CH4] is 0.25-1%, [Al]/[C] is 100ppm,a pressure during growth of 6kPa, a growth temperature of 950-1000°C, and a deposition time 1.5-6hour. Al concentration was measureded by secondary ion mass spectroscopy (SIMS).In CH4 concentration of 0.25%, the sample deposited under 950°C and 1000°C have 10
16and 3×10
16 cm
-3 of aluminum concentration and film thickness was 1.5um. In all samples, boron concentration is below the detectable limit. In CH4 concentration of 1.0% , Al concentration was 5×10
16cm
-3. Al concentration increase as the growth temperature and the CH4 concentration increase . These results exhibit the first intentional Al doping into diamond. The detail result of Hall effect measurement is going to be shown in the conference.
*This research was partially supported by the Advanced Low Carbon Technology Research and Development Program
[1] A.Kawano, H.Kawarada et al., Phys. Rev. B,47, 2010.
[2] A. W. S. Williams, E. C. Lightowlers, and A. T. Collins, J. Phys.C 3, 1727 (1970).
[3] G.Zanmarchi, J.Phys.Chem.Solids,29,1727-1736(1968).
[4] S.Koizumi et al., Diam. Relat. Mater,9,935-940,(2000).
9:00 PM - N12.36
Ultrananocrystalline Diamond Contacts and Schottky Barrier Height Measurements on Pt, Mo Contacts to Single Crystal Diamond.
Erik Muller 1 , John Smedley 2 , Mengjia Gaowei 1 , Anirudha Sumant 3 , Abdul Rumaiz 2
1 Physics and Astronomy, Stony Brook University, Upton, New York, United States, 2 , Brookhaven National Laboratory, Upton, New York, United States, 3 , Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractThe performance of many diamond based devices, such as high flux x-ray beam position monitors, depend strongly on the characteristics of the diamond metal contact interface. Charge trapping from impurities in the near surface region can cause unwanted charge injection into the device leading to photoconductive gain and non-uniformity. This can be mitigated by using diamond free from defects or by using a blocking contact; typically by oxygen terminating the diamond surface prior to metal deposition. However, maintaining the blocking nature of the contact is difficult in the harsh conditions these devices experience, for example, heating the diamond too high can modify the oxygen termination. The degree to which a contact resists charge injection is characterized by the Schottky barrier height. XPS measurements will be presented measuring the Schottky barrier of various contacts (Pt, Mo, etc.) with and without oxygen termination. In addition, results demonstrating full charge collection from x-ray detectors made with nitrogen-doped ultrananocrystalline diamond (UNCD) contacts will be presented as novel, low-absorption, and robust alternative to traditional metal contacts.
9:00 PM - N12.37
Deposition of Bronze Microwires on Ultrananocrystalline Diamond (UNCD) Electrodes.
Corina Grodek 1 , Lori Lepak 1 , Michael Zach 1
1 Department of Chemistry, University of Wisconsin -- Stevens Point, Stevens Point, Wisconsin, United States
Show AbstractAs technology advances, ever smaller wires are needed for devices, for applications in electronics, medicine, and clean energy. This requires the development of economical nanomanufacturing techniques for the mass production of metal and semiconductor nanowires of various chemical compositions, shapes and sizes. Most technologically important materials are alloys. For the first time, we report the synthesis of micro- and nanowires of controlled compositions of bronze (a model alloy, composed of copper and tin) via the Electroplate-and-Lift (E&L) Lithography process. E&L Lithography is a fast, simple technique for the electrochemical synthesis of wires, which has recently been developed by undergraduate students at UWSP in collaboration with scientists at Argonne National Laboratory. The electrode is a reusable template made of ultrananocrystalline diamond (UNCD)TM, which has been patterned by photolithography into the desired shape of the wires. A very thin (~ 80 nm), conductive layer of nitrogen-doped UNCD (NUNCD) is sandwiched between two insulating layers of UNCD, to use the exposed edges of the NUNCD layer as the working electrode. Using a longer deposition times results in wires that are large enough to see under an optical microscope, thus allowing rapid determination of the voltage conditions that lead to smooth wires. Once suitable conditions have been found, a shorter deposition time can be used to make wires with diameters so small they can only be seen by scanning electron microscopy (SEM) – potentially as small as the thickness of the NUNCD layer. The deposition time determines the final diameter of the wires, but not their smoothness or their alloy composition. The smoothness of bronze wires depends on the deposition voltage. The roles of the relative concentrations of tin and copper, and of solution pH, upon the elemental composition of wires are investigated, using energy-dispersive spectroscopy (EDS).
9:00 PM - N12.38
Control of Thermal and Electrical Conduction Properties of Nanocrystalline Diamond Films.
Kungen Teii 1 , Tomohiro Ikeda 1
1 , Kyushu University, Ksuga, Fukuoka Japan
Show Abstract Diamond has the highest thermal conductivity in all materials, which at room-temperature is more than 1000 W/mK depending on the quality. The electrical conductivity of diamond films can be varied by p- or n-type doping. However, at high temperatures, diamond films show low adhesion to aluminum substrates due to a large difference in thermal expansion coefficient between diamond and aluminum. Nanocrystalline diamond films are composed mainly of two different carbon phases: the diamond phase in form of nano-sized grains and amorphous carbon at the grain boundaries. They are typically formed under C2 dimer-rich conditions by CVD in Ar-rich/CH4 plasmas. The electrical conductivity of nanocrystalline diamond films can be varied by nitrogen addition. The remaining subject is how to control the thermal expansion coefficient while maintaining the thermal conductivity. The authors showed a way of increasing the diamond/amorphous carbon volume ratio in nanocrystalline diamond films by increasing the C2 density in microwave plasma-enhanced CVD [1]. This method is based on dissociation and recombination kinetics of hydrocarbons triggered by Ar. It is possible to control the thermal expansion coefficient by varying the diamond/amorphous ratio. In this study, we examine thermal and electrical conduction properties of nanocrystalline diamond films prepared by controlling the C2 density. The films were deposited on aluminum and silica substrates with scratching pretreatment using diamond powder. The diamond/amorphous ratio in the films increased with the C2 density. The room-temperature thermal conductivity in the films increased up to more than 20 W/mK when the diamond fraction evaluated by transmission electron microscopy was increased up to about 70%. Nitrogen incorporation in the films increased the room-temperature electrical conductivity considerably, however, the thermal conductivity decreased. This suggests that a decrease in the diamond/amorphous ratio by nitrogen addition increased the thermal resistance at the grain boundaries. Moreover, oxygen incorporation decreased both the electrical and thermal conductivities. The temperature dependence of the thermal conductivity was found to be described reasonably by the phonon-hopping model in disordered materials.[1] K. Teii and T. Ikeda, Appl. Phys. Lett. 90, 111504 (2007).
9:00 PM - N12.39
Compact and Efficient HFCVD for Electronic and Bio Compatible Diamond Films.
Ratnakar Vispute 1 , Rohan Agashe 1 , Andrew Seiser 1 , Lance Robinson 1
1 , Blue Wave Semiconductors, Baltimore, Maryland, United States
Show AbstractDiamond films are attractive for electronic, optical, biological and mechanical applications because of their excellent hardness, strength, chemical and thermal stability, bio-compatibity, thermal conductivity, breakdown voltage, hole and electron mobility, radiation hardness, and optical transmission. A compact and efficient hot filament chemical vapor deposition system has been designed for growing diamond films for electronic (photocathode detector) and biological filtration applications. Diamond films of various morphologies have been grown on silicon and GaN/sapphire substrates. Diamond seeding and masking techniques have been developed to address specific applications. Diamond films have been characterized using x-ray diffraction, Raman Spectroscopy, scanning electron microscopy and atomic force microscopy, and electrical resistivity measurements. Our results indicate that substrate rotation not only yields uniform films across the wafer, but crystallites grow larger than without sample rotation. Results are discussed in the context of lateral growth of diamond to improve in-plane crystallite size, film uniformity, deposition efficiency for wafer-based electronic applications. The optimized parameters were used to further develop diamond films for photocathode detector and bio filtration applications. One specific bio-application is the creation of a diamond filter by depositing masking technique where diamond growth was prohibited by catalytic action. Another application that we are developing includes visible blind detector technologies, especially the ultra-violet (UV) spectral range between 90 and 300 nm. Since this spectral range is accessible only from space, it is important to have a strong UV to visible rejection ratio in the optical detection process. A tunable UV detector with a strong UV to visible rejection ratio could benefit space exploration as this region (UV light from 90 to 300nm) contains the highest known density of spectral information for planets, stars, interstellar and intergalactic gas, and galaxies of any electromagnetic band. In this context we developed diamond films on GaN/sapphire windows for photocathode development. In order to exploit HFCVD diamond for wafer-based electronics applications such as cold cathode field emitters, high thermal conductivity substrate materials for white LEDs, bio-applications and high power Schottky diodes, diamond deposited substrate areas need to be scaled up without loss of uniformity or film quality. The main motivation of the present study is to identify the effects of various processing parameters on growth of diamond films on a rotating substrate or wafer to achieve uniform diamond films over large area substrate
9:00 PM - N12.4
Micro-Organic Light-Emitting Devices Fabricated by Room-Temperature Curing Nanoimprint Lithography Using Diamond Molds.
Ippei Ishikawa 1 , Taisuke Okuno 1 , Shuji Kiyohara 1 , Yoshio Taguchi 2 , Yoshinari Sugiyama 2 , Yukiko Omata 2 , Yuichi Kurashima 3
1 Electric and Control System Engineering Course, Maizuru National College of Technology, Maizuru,Kyoto Japan, 2 Application and Technical Section, ELIONIX INC., Hachioji,Tokyo Japan, 3 Department of Mechanical Systems Engineering, University of Yamanashi, Kofu,Yamanashi Japan
Show AbstractOrganic light-emitting devices (OLEDs) are self-luminous and do not require a backlight, which leads to many advantages, including low operating voltage, low power consumption, wide viewing angle, fast response time, light weight, high contrast ratio and thin structure compared with the liquid crystal panel, and are expected to be applicable in next-generation flat panel displays. We have investigated the fabrication of micro-OLEDs by thermal-cycle nanoimprint lithography (NIL) using a diamond mold. The diamond mold has been fabricated by electron cyclotron resonance (ECR) oxygen ion shower (ELIONIX Co., Japan, EIS-200ER) with polysiloxane [-R_2SiO-]n (Hitachi Chemical Co., Ltd., Japan, HSG-R7-13) oxide mask in the electron beam (EB) lithography technology, and has life time about 100 times longer than that of silicon (Si) and silicon dioxide (SiO_2) molds using a conventional NIL process because diamond has many unique properties such as high thermal conductivity and low thermal expansion. However, light emissions from 30 µm-square-dot OLEDs fabricated by thermal-cycle NIL using diamond molds have not been uniform. To overcome this problem, we have proposed the fabrication of micro-OLEDs by room-temperature curing (RTC)-NIL. Compared with the microfabrication process of OLEDs by thermal-cycle NIL, RTC-NIL has advantages including a short step, high throughput, low cost, high resolution and low damage of the emitting layer because of patterning used in physical change of imprint resist. The polysiloxane was used EB resist and oxide mask material in EB lithography and was also used as RTC-imprint resist material, and is in the state of sticky liquid at room temperature and stable in air exhibits a negative-exposure characteristics. A polished polycrystalline diamond film (A.L.M.T. Co., Ltd., Japan) (12 µm-thickness, 1.5 nm-arithmetic average roughness) synthesized by chemical vapor deposition (CVD) method on Si substrate (10×10 mm-square, 3.2 mm-thickness) was used as a mold material. We have fabricated diamond molds of microdot with 5 µm-diameter and -width of 10 µm-pitch which have 500 nm-height. We carried out the RTC-NIL process using diamond molds under the following optimum conditions : time from spin-coated to imprint of 1 min, imprinting pressure of 0.5 MPa and imprinting time of 5 min. The microdevice structure of 5 µm-circle- and -square-dot micro-OLEDs fabricated by RTC-NIL using the diamond mold is indium tin oxide (ITO) [anode] / N,N'-Diphenyl-N,N'-di(m-tolyl)benzidine (TPD) (Tokyo Chemical Industry Co., Ltd., Japan, D2448) (40 nm-thickness) [hole transport layer] / Tris(8-quinolinolato)aluminum (Alq_3) (Tokyo Chemical Industry Co., Ltd., Japan, T1527) (40 nm-thickness) [electron transport layer] / aluminum (Al) (200 nm-thickness) [cathode]. The microfabrication and operation of micro-OLEDs in RTC-NIL using diamond molds were successfully demonstrated.
9:00 PM - N12.40
Characteristics of a New CVD Diamond CMP Pad Conditioner.
Rakesh Singh 1 , Andrew Galpin 1 , Daniel Wells 1 , Joseph Smith 1
1 Contamination Control Solutions, Entegris, Inc., Billerica, Massachusetts, United States
Show AbstractKey attributes of a revolutionary novel design – SiC with high integrity, non-contaminating CVD Diamond technology chemical mechanical planarization (CMP) pad conditioner will be presented with empirical data. This innovative conditioner design provides maximum abrasive efficiency, extends pad lifetime, eliminates diamond fall-out issues, and results in tunable and much gentler conditioning for a consistent, smooth CMP pad surface throughout its lifetime. Several 4” commercially available and new pad conditioners were analyzed using a Buehler benchtop polisher, Center for Tribology benchtop tribometer, and an Araca APD-800 300mm wafer polisher to determine the pad cut-rate, surface roughness, coefficient of friction (COF), and copper wafer material removal rate. Results are presented and discussed for the effect of pad conditioner parameters, including abrasive/feature type/size and distribution, on the pad cut-rate and surface roughness behavior. Marathon test tribological data obtained for different design pad conditioners will be evaluated to compare the consistency of different designs over extended periods of operation. Empirical results of pad cut-rate and surface roughness, and wafer polishing rate are correlated together with pad and conditioner design, material and operational parameters. Such attributes of pad conditioner designs, pad cut-rate and surface morphology, as well as the wafer polishing rate is extremely important in advanced processes, to limit the pad conditioner optimization time in fab environment. This study shows the importance of pad conditioner laboratory evaluations for the next-generation CMP processes.
9:00 PM - N12.41
De-Aggregation of Nanodiamond Powders Using Salt- and Sugar-Assisted Milling for Drug Delivery Applications.
Amanda Pentecost 1 2 , Shruti Gour 3 2 , Vadym Mochalin 1 2 , Isabel Knoke 1 2 4 , Yury Gogotsi 1 2
1 Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania, United States, 2 A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, Pennsylvania, United States, 3 Biomedical Engineering, Drexel University, Philadelphia, Pennsylvania, United States, 4 Materials Science & Engineering, University of Erlangen-Nurnberg, Erlangen Germany
Show AbstractNanodiamond delivers all of the advantages of bulk diamond at the nanoscale in the form of 4-5 nm diameter particles. These advantages include, but are not limited to: superior mechanical properties, biocompatibility, and chemical stability. In addition to these superior properties of diamond, nanodiamond features a large, accessible and tailorable surface. This unique combination of properties explains a growing interest to nanodiamond as a platform for applications ranging from lubricants, nanocomposites, to drug delivery systems and biomedical imaging. In order to fully benefit from these excellent properties, it is essential to produce single nanodiamond particles. Unfortunately, all nanodiamond powders have a strong tendency to form aggregates, each several micrometers in size. It is important to break down the aggregates and separate the primary diamond particles However, this has proven to be an extremely difficult task due to the unusually tight nature of these aggregates. We propose to solve this problem by dry milling of nanodiamond with sodium chloride, sugar, and other crystalline materials hard enough to assist in breaking the nanodiamond aggregates. As sodium chloride particles are milled, they shear diamond aggregates, separate and isolate nanodiamond particles without damaging them. These milling aids can easily be removed after milling by rinsing with water, allowing the final product to be free of contaminants introduced by non-soluble ceramic milling aids, such as zirconia, silica etc. used in other techniques to disintegrate nanodiamond aggregates. Then, by adjusting the pH of the solution to 11.4, thus creating a basic environment, a stable colloidal solution of single nanodiamond particles that repel each other can be obtained. One use of single nanodiamond particles is in drug delivery systems. Because of their surface charges, nanodiamond can easily adsorb antibiotics on its surface. Consequently, these the release of these antibiotics can be controlled via such methods as ultrasound.
9:00 PM - N12.42
Effect of Substrate Temperature and Methane Feeding on CVD of Diamond Using a Mixture without and with Argon.
Divani Barbosa 1 , Patricia R Barreto 2 , Mauricio Baldan 1 , Vladimir Trava-Airoldi 1 , Evaldo Corat 1
1 Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, São Paulo, Brazil, 2 Laboratório Associado de Plasma, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, São Paulo, Brazil
Show AbstractWe report a systematic investigation of the effect of substrate temperature and methane feeding in Hot Filament Chemical Vapor Deposition (HFCVD) of diamond. We performed this study using either a mixture without or with a high concentration of argon. The standard HFCVD used has an independent substrate temperature control, adjustable between 823 to 1173 K. To explicitly elucidate the function of argon addition, for the first set of experiments the gas mixture was composed only by methane and hydrogen. Methane content varied in the range 1 to 18 vol.%, balanced with hydrogen. For the second set of experiments, in an argon rich environment, methane and hydrogen concentrations were the only parameters changed. The feed gas mixture varied with 0.125 to 2 vol.% methane balanced to 10 vol.% with hydrogen, and 90 vol.% argon. Scanning electron microscopy (SEM) images showed the morphologies. Raman scattering spectroscopy was used for estimated the degree of order in the clustered aromatic sp2 phase and sp2/sp3 relative concentrations. X-ray Philips PW-1840 difractometer allowed measurements of diamond crystallite size to estimate renucleation rate. We simulated the principal chemical species involved, in the respective gas phase environments, using a free version of the Chemkim computer package. A comparison of the activation energies found here, by other authors, and the films properties indicate similar behavior, which depends on concentration of methane and hydrogen. It is nearly independent of the argon presence in the feeding gas mixture. Comparison with gas phase simulation indicates that the increase of large hydrocarbon content, especially C2Hx species, is responsible for the increase of renucleation rate and sp2 content in the film and, also, to the decrease of growth rate at UNCD conditions.
9:00 PM - N12.46
Fabrication of Nano-Needle Arrays on Diamond Surface by Reactive Ion Etching.
Takayuki Misu 1 , Keishin Koh 1 , Toshihiko Arai 2
1 Home Electronics Engineering, Kanagawa Intitute of Technology, Atsugi Japan, 2 Electrical and Electronic Engineering, Kanagawa Institute of Technology, Atsugi Japan
Show Abstract Diamond is considered to be a good cold cathode material because of its unique properties such as negative electron affinity. The negative electron affinity of the diamond surface is expected to enable the realization of an efficient electron emitter for flat display panels and cold cathode lamps. Recently, the high electron emission is obtained by the nano-needle arrays on the diamond surface. In this study, CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The nano-needle array of high aspect on diamond substrate surfaces obtained with MgO electrode was fabricated by using back-sputtering from MgO electrode. The electrode samples used are chemical vapor deposited (CVD) non-doped polycrystalline diamonds (10×10mm) of 0.2mm thickness. The surface treatment was conducted in two settings : (1) using a conventional stainless steel electrode for the cathode in the RIE system, and (2) placing a MgO sintered ceramic (5mm thickness) on the cathode. A 99.9 % pure MgO sintered ceramic was used as a back-sputtering target. The stainless steel and MgO electrodes were both 70mm in diameter and 20mm in electrode distance. The discharge conditions of RIE system were RF power of 100W at 13.56MHz, O2 gas pressure of 10Pa, and O2 gas flow rate of 20sccm. After etching the sample with O2 plasma for 2hours, the root mean square (RMS) roughness of the diamond surface roughness etched by using the stainless steel and MgO electrodes was determined by an atomic force microscope (AFM). The root mean square (RMS) roughness of the diamond surface was determined by AFM. The value of RMS roughness is higher on the diamond surface etched using the MgO electrode, indicating attainment of higher aspect ratios. The diamond surface etched using the MgO electrode was analyzed by X-ray photoelectron spectroscopy (XPS), and presence of MgO was confirmed. The high density capacitively coupled RF plasma has been produced using MgO electrodes with a high secondary electron emission coefficients. The Plasma density with MgO electrode is higher than that stainless steel electrode. It is seen that the attachment of MgO particles on the diamond surface increases by back-sputtering from the MgO electrode. The micro mask of MgO particles is formed on the diamond surface and the surface is selectively etched.
9:00 PM - N12.5
Large Area Deposition of Carbon Nitride Films by Newly Liquid Phase Technique.
Mikiteru Higashi 1 , Hideo Kiyota 2 , Tateki Kurosu 3 , Masafumi Chiba 1
1 Mat. Chem., Tokai Univ., Numazu, Shizuoka, Japan, 2 Mecha. sys. eng., Tokai Univ., Kumamoto, Kumamoto, Japan, 3 Appl. Comp. Eng., Tokai Univ., Hiratsuka, Kanagawa, Japan
Show AbstractTo resolve the problems of signal delay and excessive power consumption caused by downsizing of ultra -large- scale integrated (ULSI) circuits, there is a demand for continued reduction of parasitic capacitance due to the dielectric material in multilevel interconnections used for ULSI circuits. Recently, carbon nitride was reported to indicate low dielectric constant [1]. In general, carbon nitride films have been prepared using various vapor deposition techniques [2]. On the other hand, the deposition of the carbon nitride films has been accomplished by electrochemical processes using liquids such as acrylonitrile [3]. Liquid phase deposition offers the following advantages over conventional vapor deposition: simple experimental apparatus, low deposition temperature, and scalability of the deposition area. Therefore, it is necessary to further examine the feasibility of using liquid phase deposition to prepare carbon nitride dielectric films. In a previous study, by employing liquid phase deposition using acrylonitrile, we successfully prepared carbon nitride films with dielectric constant as low as those of the materials prepared by the conventional vapor deposition techniques [4]. It is necessary to deposit a dielectric material in multilevel interconnections used for ULSI circuits on a large area substrate. Therefore, we attempted to deposit carbon nitride films on a large area Si substrate by liquid phase deposition using acrylonitrile. The carbon nitride films are deposited by supplying DC bias voltage to Si substrates (max. 70×70 mm2) immersed in acrylonitrile. The experimental apparatus used for liquid phase deposition consisted of a hot plate, a glass vessel, two Ti electrodes, a thermometer, a Dimroth condenser and a DC power source. Continuous and uniform films were deposited by supplying positive bias voltage. X-ray photoelectron spectra of the films showed the presence of C, N, and O atoms as major components in the deposited films. The atomic N/C ratio was determined to be approximately 0.3 – 0.5, which is comparable to those of carbon nitride films prepared by conventional vapor deposition techniques. This experimental result indicates that liquid phase deposition is an effective technique to achieve scalability of the deposition area.Acknowledgements: This work was supported in part by Grant-in-Aid for Scientific Research (C) 22560303 of Japan Society for the Promotion of Science (JSPS). The part of this work was supported on “A Subsidy for Activating Educational Institutions 2011” by Tokai University.References: [1] M. Aono and S. Nitta: Diamond Relat. Mater. 11 (2002) 1219. [2] S. Muhl and J. M. Mendez: Diamond Relat. Mater. 8 (1999) 1809. [3] H. Kiyota, H. Gamo, M. Nishitani-Gamo, and T. Ando: Jpn. J. Appl. Phys. 47 (2008) 1050. [4] M. Higashi, H. Kiyota, T. Kurosu, and M. Chiba: Jpn. J. Appl. Phys. 50 (2011) 061502.
9:00 PM - N12.6
Influence of the Doping Level at Boron Doped Nanocrystalline Diamond Films in the Electrochemical Determination of Nitrite.
Jorge Matsushima 1 , Diego Souza 1 , Fernando Souza 1 , Adriana Azevedo 1 , Mauricio Baldan 1 , Neidenei Ferreira 1
1 Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, São José dos Campos Brazil
Show AbstractThe excellent electrochemical response of the boron doped diamond electrodes is of fundamental importance in electroanalysis of organic and inorganic substances considered as environment pollutants. News experimental approaches to improve the diamond properties have been evidenced. One them is the production of boron doped nanocrystalline diamond (BDND) films, which may result in an increase of the electroative area due to the decrease of diamond grain size. So, the electroanalytical signal can improve and small quantities samples can be analyzed. Based in these considerations, the goal of this work is evaluate the doping level effect of the BDND films as function to the electrochemical determination of nitrite. Actually, nitrite is one of nitrogen species of great preoccupation due to the eutrophication of aquatic system and detrimental effects to health human by formation of carcinogenic substances (N-nitrosamines). Nitrite salts are commonly used as fertilizers, corrosion control and additive for meat products. Hence, the nitrite increase in natural water is inevitable and their control is of fundamental importance. Among the numerous methodologies for nitrite analysis, the electrochemical detection presents some advantages since that offers a simples and rapid determination. BDND were grown on Si substrate by filament chemical vapor deposition technique: temperature of the 900K, pressure of the 6.7 kPa, deposition time of the 6h and gas mixture of CH4/H2/Ar with flux of 1/19/80 sccm. Boron precursor was obtained by forcing H2 through a bubbler with B2O3 dissolved in methanol. The dissolution of 10000 ppm and 30000 ppm of B2O3 covered a range of B/C ratio corresponding to the acceptor densities values with 1020 and 1021 cm-3 analyzed by Mott-Shottky plots, respectively. The electrochemical measurements were carried out using Autolab PGSTAT 302 equipment with a three-electrode cell. BDND were used as a working electrode, a platinum wire served as counter electrode and Ag/AgCl electrode was used as reference. The nitrite determination was carried out using as-grown BDND and hydrogen plasma treated BDND. The detection limit was evaluated by square wave voltammetry using Britton-Robinson buffer solution. The 30000 ppm BDND electrode showed high sensibility to nitrite in the as-grown condition. This behavior may be justified to the better morphological and structural conditions associated to electrochemical area, surface roughness, sp2 carbon amount and surface terminations. On the other hand, 10000 ppm BDND electrode showed higher sensibility to nitrite after the hydrogen plasma treatment, which is associated to surface modification, particularly, with respect to sp2 carbon impurities in the grain boundary.
9:00 PM - N12.7
Copper Photoelectrodeposition onto Boron Doped Diamond Electrodes at Different Doping Level to Enhance Nitrate Electroreduction.
Andrea Couto 1 , Maurício Baldan 1 , Neidenei Ferreira 1
1 Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, São José dos Campos Brazil
Show AbstractA feature of the semiconductors is their photoactivity. So, the photo-assisted metal deposition method is very useful for the preparation of efficient electrode material. The diamond in its natural state is considered a semiconductor with band gap energy of 5.5 eV. Due to its extremely wide band gap and the fact of the conduction band edge is located at a very negative potential (-4.0 V versus SHE), the photogenerated electrons have extremely high reducing power. So, the diamond serves as both a source of electrons for reduction of the ion to be deposited and a substrate for deposition process. Thus, the aim of this work is to investigate the photoelectrodeposition of copper on semiconducting boron doped diamond (BDD) films with different doping levels. Furthermore, these modified electrodes were applied to nitrate electroreduction, since the copper catalyses this process. BDD films were deposited on the silicon substrate by hot filament-assisted chemical vapor deposition technique. The films were grown from H2/CH4 gas mixture with a pressure of 50 Torr and substrate temperature around 800°C, during 16 h. Boron source was obtained by an additional hydrogen line passing through a bubbler containing B2O3 dissolved in methanol with a controlled B/C ratio that led to films with different doping level (1019 and 1021 atoms.cm-3). The Cu particles photoelectrodeposition on BDD films was performed under potentiostatic mode, at a fixed potential of -0.6 V during 10 min in a 1 mmol L-1 CuSO4, 50 mmol L-1 H2SO4 aqueous solution, under ultra-violet (UV) irradiation. The light source was a home made system, composed by a set five commercial lamps (Philips TUV 30 W/G30T8) placed in a closed box. The UV irradiance at the electrode position was 12 W/m2 measured by a radiometer. The UV irradiance on BDD surface generated additional electrons at the conduction band, which ensured a high Cu particle density. High deposit uniformity was observed at the grain faces by scanning electron microscopy for both electrodes. Nitrate reduction experiments were monitored by linear sweep voltammetry using 0.01 mol L-1 KNO3 + 0.001 mol L-1 Britton-Robinson buffer (pH=3). The results showed that the nitrate reduction is catalyzed by Cu deposited on BDD surface. The nitrate electroreduction on both as-grown BDD electrode just only one cathodic peak is observed around -1.25 V, suggesting that nitrate reduction to ammonia is taking place at this potential. The effect of Cu deposits on the BDD surface was more pronounced in the BDD with high doping. The appearance of a slight new peak at around -1.0 V is visible, associated to nitrate reduction into hydroxylamine followed by the ammonia peak. The stability of Cu particles on these films was evaluated from successive linear sweep voltammetry measurements for the nitrate reduction presenting good reproducibility.
9:00 PM - N12.8
Influence of the Anions Nature on the Nitrate Electrochemical Reduction Using Boron Doped Diamond.
Andrea Couto 1 , Jorge Matsushima 1 , Eduardo Saito 1 , Maurício Baldan 1 , Neidenei Ferreira 1
1 Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, São José dos Campos Brazil
Show AbstractNowadays, the electrochemical process appears as an alternative technique for the solution of environmental problems. Nitrate has been considered an important environmental contaminant of soil and natural waters, mainly due of the excessive use nitrogen fertilizers in the soil especially in rural and agricultural areas in many regions worldwide. The electrochemical reduction of nitrate to harmless nitrogen has been studied extensively during the last years in numerous works. Particularly, boron-doped diamond (BDD) has been shown highly promising for application in electroanalysis process. The singular properties of diamond, mainly the high anodic and cathodic potential of the water electrolysis, make this material with great potential for studying the processes of nitrate reduction, since its reduction takes place at very negative potential. It is known that the nature of electrolyte affects the kinetic of the nitrate reduction. Most of the studies involving the influence of electrolyte have been focused on the interference of the alkalimetal cation electrolyte while the anion nature has received less attention. Thus, the goal of this work was evaluated the influence of some anions electrolytes on the rate of the nitrate reduction using boron doped diamond electrode with different doping level (1019 and 1021 atoms.cm-3). BDD films were grown by hot filament-assisted chemical vapor deposition technique on the silicon substrate, activated by methane hydrogen gas mixture with a pressure of 50 Torr and temperature around 800°C, during 16 h. Boron source was obtained by an additional hydrogen line passing through a bubbler containing B2O3 dissolved in methanol with a controlled B/C ratio. Nitrate reduction experiments were monitored by linear sweep voltammetry, at 50 mV s-1, using 0.01 mol L-1 KNO3 containing different solutions: 0.001 mol L-1 Britton-Robinson (BR) buffer (pH=3), 0.001 mol L-1 H2SO4 e 0.001 mol L-1 HClO4 solution. The results showed that all tested electrolytes presented activity on the nitrate reduction. For BDD with low doping level, the voltammetric curves revealed a significant increase in the current of the nitrate reduction in the order ClO4- < PO4-, BO33-, CH3COO- (BR buffer) < SO42- while for BDD with high doping level the obtained sequence is PO4-, BO33-, CH3COO- (BR buffer) < SO42- < ClO4-. This difference of behavior may be associated to the morphological condition of these films. The BDD electrode with low doping level presented a smooth surface, the sequence obtained may be justified only by the ionic strength contribution. On the other hand, BDD with high doping level presented a rougher surface and hence might lead to anions adsorption effects on the electrode surface.
9:00 PM - N12.9
Interaction of Pseudomonas Aeruginosa with Hydrogenated Amorphous Carbon Surfaces.
Jose Nocua 1 4 , Olga Medina 1 4 , Samuel Escobar 4 , Fabrice Piazza 3 , Javier Avalos 2 4 , Gerardo Morell 1 4
1 Department of physic, University of Puerto Rico, Rio Piedras, Puerto Rico, United States, 4 , Institute of Functional Nanomaterials, San Juan, Puerto Rico, United States, 3 , Pontificia Universidad Católica Madre y Maestra, Santiago, Santiago, Dominican Republic, 2 Department of Physics, University of Puerto Rico at Bayamón, Bayamon, Puerto Rico, United States
Show AbstractPseudomonas aeruginosa is a gram-negative bacterium potentially pathogenic for humans, which contaminates implants. The biofilms formed by these bacteria cause high resistance to antibiotics and disinfectants. There is high interest in developing antibacterial coatings to prevent biofilm growth. Hydrogenated amorphous carbon (a-C:H) deposited at near room temperature is a potential candidate for protective and antibacterial coatings of surgery tools and medical implants. The relation between the bacterial colonisation factor, and the material’s composition, structure, topography, surface energy and mass-density was examined. a-C:H were grown by distributed electron cyclotron resonance plasma from C2H2. A wide variety of films, fromo low-mass density (1.2g/cm3) polymerlike carbon to high density (2.4 g/cm3) tetrahedral a-C:H was considered. The films composition, structure, topography and physical properties were charaterized by Raman spectroscopy, electron energy loss spectroscopy, electron diffraction, laser induced surface acoustic waves, Fourier transform infrared spectroscopy, spectroscopic ellipsometry, atomic force microscopy and contact angle measurements
Symposium Organizers
Oliver A. Williams Cardiff University
Richard B. Jackman University College London
Philippe Bergonzo CEA-LIST
Greg N. Swain Michigan State University
Kian Ping Loh National University Singapore
N13: Diamond as a Tool for Biology
Session Chairs
Thursday AM, December 01, 2011
Room 306 (Hynes)
10:00 AM - N13.1
Tuning of Electrochemical Performances of B-Doped Diamond Electrodes for Medical Implants.
Lars Grieten 1 , Stoffel Janssens 1 , Milos Nesladek 1 2 , Ken Haenen 1 2 , Patrick Wagner 1 2
1 Institute for Materials Research, Hasselt University, Diepenbeek, Limburg, Belgium, 2 IMOMEC, IMEC vzw, Diepenbeek, Limburg, Belgium
Show AbstractRecent interests of using B-doped nanocrystalline diamond layers (BNCD) for neuro-prosthetics have risen demands of optimization of electrochemical performances of the diamond electrodes design. In this work we have studied and optimized the characteristics of B-doped NCD electrodes, deposited on Pt-Ir substrates, by cyclic voltammetry and electrochemical impedance spectroscopy. The critical issue for high charge transfer in neural cell applications is the enhancement of the electrode capacitance to obtain high signal/noise ratio performance in vivo. However diamond is known to show lower values of the double layer capacitance compared to metallic electrodes such as Pt-Ir. The aim of this work is two-folded. In the first part we carry out precise modelling of impedance data of optimized micro-electrode arrays (MEAs). Including pseudo potentials and cationic processes at the surfaces. Our MEA have a potential window of 3.9 – 4 eV (i.e. Faraday current is lower as 1 mA/cm2 for phosphate buffer saline (PBS) electrolytes, peak separation +/- 70 mV in ferricyanide). In the second stage we carry out optimization of the Helmholtz layer capacitance by interactively designing an optimal surface, leading to values of 30 µF/cm2 and higher for BNCD. Finally we compare the performances of BNCD and Pt-Ir electrodes in PBS buffers and carry out in vitro tests in neural cultures. We evaluate the cells viability, and minimise the pH-changes by reducing the Faradaic components of the ionic currents in neural cells
10:15 AM - N13.2
Diamond Micro Electrode Array (MEA) as Electrophysiology Platforms with High Performance and Stability.
Lionel Rousseau 1 , Alexandre Bongrain 2 1 , Raphael Kiran 2 , Blaise Yvert 5 6 , Emmanuel Scorsone 2 , Amel Bendali 3 4 , Gaelle Lissorgues 1 , Serge Picaud 3 4 7 , Philippe Bergonzo 2
1 , ESIEE-ESYCOM, Noisy le Grand France, 2 , CEA-LIST, Gif-sur-Yvette France, 5 , Université de Bordeaux, Bordeaux France, 6 , CNRS INCIA, Bordeaux France, 3 , INSERM U968, Paris France, 4 , UPMC UMR_S968, Paris France, 7 , Fondation Rothschild, Paris France
Show AbstractMicro Electrode Arrays (MEAs) are common electrophysiology tools enabling to probe the neuronal activity distributed over large populations of neurons or from embryonic organs. MEAs enable to record neuronal network activities while delivering specific electrical stimulations. Specific MEAs can be also used to build neural prosthesis or implants to compensate function losses due to lesions or degeneration of part of the Central Nervous System (CNS) such as for Parkinson disease treatment, or for cochlear or retinal implants. Such MEAs commonly use gold, platinum, black platinum or iridium oxide as electrodes to ensure the contact to cells. One critical problem encountered when using microelectrodes with these materials is the narrow potential window they offer before medium direct ionisation. This implies that high currents may degrade the electrodes and alter the tissue itself. Also, the progressive fouling of the electrode is an issue since it leads to the loss of sensitivity of the MEAs, and this is particularly crucial when cultures are probed during several weeks.This paper describes a new approach involving the use of Boron Doped Diamond (B-NCD) to fabricate MEAs composed of 64 electrodes. The active layers were produced either on glass or oxidised silicon from a SEKI 6500 reactor producing 4 inch wafers on which conventional lithographic steps were conducted. Several approaches have been used successfully, with varying geometrical structures according to the technological route. For example, the active diamond layer can correspond to the growth side of the material or to the seeding side, with influence on the resulting assembly. Fabricated MEAs were characterized using electrochemical measurements in ferri/ferrocyanide 1mM (cyclic voltametry and Electrochemistry Impedance Spectrocscopy (EIS)) and their performances compared with that of Pt identical devices.Two preparations were used for tests : (i) cultures of retinal ganglion cells (CGC) and (ii) organotypic cultures of mouse spinal cords. The tests demonstrated that no difference could be observed with respect to glass control. Also, no proteinic coating was found to be necessary to ensure cell growth. We show that B-NCD offers several advantages when compared to metallic materials. Its carbon surface offers high biocompatibility, and the B-NCD potential window is about twice that of Pt. In-vitro 64 B-NCD MEA were tested with retina of rat and spinal cords. We recorded spontaneous activity (local field potential (LFP) and spikes. Stimulation was also achieved and the possibility to inject higher current levels was demonstrated using B-NCD than with Pt. The local pH variations were probed in the vicinity of these microelectrodes during electrical stimulation and we observed significant improvements of the charge injection capabilities over conventional platinum microelectrodes.
10:30 AM - N13.3
Ultrananocrystalline Diamond (UNCD) Bioinert/Biocompatible Coating for Implantable Biomedical Devices for Treatment of Glaucoma in Human Eyes.
Orlando Auciello 1 2 , Pablo Gurman 1 , Ana Sanseau 3 , Mario Saravia 4 , Alejandro Berra 3
1 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 2 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 3 Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Buenos Aires, Argentina, 4 Hospital Universitario Austral, Universidad Austral, Pilar, Buenos Aires, Argentina
Show AbstractResearch is reported to develop UNCD films as bioinert/biocompatible coatings to produce implantable devices for the human eye, without biofouling, a host response against implants characterized by an inflammatory response followed by fibrosis around the implant. This work represents a fundamental step towards insertion of prosthetics into the eye for the treatment of glaucoma, a condition that induces eye overpressure, resulting in optical nerve damage, which ultimately could lead to blindness. Glaucoma valve silicone-based components, currently used as the main drainage device for glaucoma treatment, were coated with UNCD films, using the current low temperature process developed by our group, which produces UNCD films at about 400 C, exhibiting excellent biological performance when implanted in a rabbit eye, with no rejection (no fibrosis), while the same component without UNCD coating, implanted in the other eye of the same rabbit, exhibit extensive inflammatory response (fibrosis).Histological studies will be presented showing the greatly improved biocompatibility provided by the UNCD coating. Although the silicone component of the glaucoma valve sustained the 400 C UNCD deposition without major degradation, the material became slightly hardened. Therefore, it is important to develop a UNCD film growth process that allows growing UNCD films at temperatures ≤ 300 C. In this respect, we will discuss first steps in the development of low temperature (≤ 300 C) synthesis of UNCD films, using a bias enhanced nucleation-bias enhanced growth process, which would enable deposition of UNCD films on polymers used in many implantable devices such as the glaucoma valve.In conclusion, UNCD films greatly improve the biocompatibility of glaucoma valves. Future clinical studies in humans are projected to complete the preclinical animal studies presented here.This work was supported by US Department of Energy, Office of Science, Office of Basic Energy Sciences-Materials Science, under contract DE-AC02-06CH11357. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
10:45 AM - N13.4
In Vitro Biomolecular Sensing Using Chemical Driving on NV Centers via Charge Transfer by Interactions with Polar and DNA Molecules.
Vladka Petrakova 1 3 , Frantisek Fendrych 1 , Andy Taylor 1 , Mirek le Dvina 4 , Peter Cigler 4 , Anna Fiserova 5 , Milos Nesladek 2 3
1 Institute of Physics, Academy of Sciences of the Czech Republic, Prague 8 Czechia, 3 Faculty of Biomedical Engineering, Czech Technical University, Kladno, Czechia, 4 Institute for Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague 6 Czechia, 5 Institute for Microbiology , Academy of Sciences of the Czech Republic, Prague 4 Czechia, 2 IMO, Hasselt University, IMOMEC division IMEC, Diepenbeek Belgium
Show AbstractIn our recent works on optically-traceable intracellular nanodiamond particles, we have demonstrated that photoluminescence (PL) can be driven chemically by changing the occupation of NV- and NV0 states by H- or O-termination. Upon H-termination NV- luminescence quenches. In this work we show that PL changes of higher magnitude can be accomplished by working with stronger polar bonds, such as C-F, on the ND surface and attaching, by ionic binding, molecules such as several kinds of polymeric chains or bimolecular structures such as DNA or RNA, for targeted drug delivery. We observed changing sensitivity of NV PL to positive and negative charges developed close to diamond surface depending on the type of surface termination, where fluorinated ND exhibited highest sensitivity. We further discuss differences in ND internalisation in cancer cell cultures with respect to their stability of chemo- and bio-environment. This situation is modelled by using surface interactions (F, H, O) of ND and the chemical potential of the liquid environment. Hydrogenated, oxidised and fluorinated HPHT ND with size distribution of 10-50 nm HPHT ND was used in this study. NV centres were produced by 5.6 - 10.6 MeV proton irradiation and subsequent annealing. To be able to bond F on to the diamond surface, we have developed a new wet chemistry method using ionic fluorination, allowing very high F-atomic coverage of 36 %, as studied by elemental analysis and IR spectroscopy. Raman and PL (514 nm) spectra were taken from a colloidal dispersion of treated ND and after attachment of negatively and positively charged molecules such as specific polymers (PDADMA C or PSSNa) with different dispersion pH. The measurements of chemical process for cancer cell lines are monitored with single particle resolution.
N14: Diamond for Devices
Session Chairs
Thursday PM, December 01, 2011
Room 306 (Hynes)
11:30 AM - N14.1
Direct Integration of Low Temperature Grown Nanocrystalline Diamond with GaN for Efficient Thermal Management.
Anirudha Sumant 1 , Vivek Goyal 2 , Desalegne Teweldebrhan 2 , Alexander Balandin 2
1 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 2 Department of Electrical Engineering and Materials Science and Engineering Program, University of California Riverside, Riverside, California, United States
Show AbstractIt is well-known that semiconductor devices based on AlGaN/GaN materials can sustain operation at high power densities due to an exceptionally high breakdown voltage. However, existing heat-extraction technology limits the maximum achievable power density from GaN and common substrates used for its growth (e.g. silicon, sapphire) due to poor thermal properties. Direct deposition CVD-diamond on GaN have been tried, however, due to the high substrate temperature requirement of diamond deposition process (700-800 oC), it has been observed that GaN starts to degrade due to either diffusion of carbon in to the GaN lattice or loss of N from the GaN lattice leading to degradation of performance of overall semiconductor layers deposited on GaN. It is therefore very important to achieve good quality diamond film on GaN substrate at reasonably low substrate temperatures (400-500 oC). We demonstrates a novel approach based on nanocrystalline diamond films grown using Ar/CH4/H2 gas chemistry to deposit good quality nanocrystalline film directly on the GaN substrate at low substrate temperatures (400-500oC). We have carried out in-plane and cross-plane thermal conductivity measurements on NCD/GaN structures. Results show that there is moderate increase in effective thermal conductivity of the composite NCD/GaN structure at elevated temperatures surpassing the thermal conductivity of silicon. We will discuss the possible mechanisms involved, and specific advantages offered by thin nanocrystalline diamond for efficient thermal management. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.The work in Balandin group at UCR was supported, in part, by DARPA – SRC Center on Functional Engineered Nano Architectonics (FENA).
11:45 AM - N14.2
Charge Transfer Mediation in P3HT PCBM Bulk-Heterojunction Solar Cells by Using Graphene.
Pieter Robaeys 1 , Emilie Bourgeois 1 , Jean Manca 1 , Ken Haenen 1 2 , Kiran Kimura 3 , Milos Nesladek 1 2 , Kian Loh 3
1 Institute for Materials Research , Hasselt University, Diepenbeek Belgium, 2 IMOMEC, IMEC vzw, Leuven Belgium, 3 Department of Chemistry, National University of Singapore, Singapore Malaysia
Show AbstractUnique properties of graphene attracted much attention for the use in multiple applications. It can serve as a transparent and highly conductive ultrathin material for applications ranging from flexible displays, optical modulators, to electrodes in photovoltaic solar cells. Several strategies such as chemical coupling routes have been used to construct photovoltaic solar cell including graphene mixtures with inorganic and organic compounds [1].One of the most attractive systems for organic photovoltaics is P3HT: PCBM bulk heterojunction solar cell which reaches high collection efficiencies. One of the challenges here is to enhance the open circuit voltage (Voc), which is critical for further improvement of the external quantum efficiency (EQE). Here we report on a novel mechanism to enhance the Voc by using graphene as the charge transfer mediator in P3HT: PCBM: G solar cells. By using photocurrent methods , Photothermal Deflection Spectroscopy (PDS) and Fourier Transform Photocurrent Spectroscopy (FTPS) we study the charge transfer mechanism in these organic photovoltaic structures. These techniques are known for high sensitive measurements of the optical absorption. The photocurrent could be measured over 6 orders in magnitude. We could clearly establish that graphene addition is controlling the shape of the charge transfer band [2] leading for specific concentrations to enhance the Voc. [1] Wang Y, Tong SW, Xu XF, et al. Advanced Materials, 23 p.1514-1518 2011[2] Vandewal K, Tvingstedt K, Gadisa A, , Nature Materials 8, p. 904-909 (2009).
12:00 PM - N14.3
Energy Dependent Studies of X-Ray Topography and 2D Resposivity Mapping of CVD Diamonds.
Mengjia Gaowei 1 , Erik Muller 1 , John Smedley 2 , Balaji Raghothamachar 1 , Jeffrey Keister 3 , Ilan Ben-Zvi 4 , Michael Dudley 1 , Qiong Wu 4
1 Dept. Materials Sciences and Engineering, Stony Brook University, Srony Brook, New York, United States, 2 Instrumentation Division, Brookheven National Laboratory, Upton, New York, United States, 3 National Synchrotron Light Source II, Brookheven National Laboratory, Upton, New York, United States, 4 Collider-Accelerator Division, Brookheven National Laboratory, Upton, New York, United States
Show AbstractDiamond has attracted profound attention during recent years as a promising candidate for electronic devices like secondary electron amplifier and synchrotron beamline monitor, which is made available by the advances in chemical vapor deposition (CVD) process in the synthesis of diamond. However, both devices require the diamond to have uniform electronic performance, which is proved to be diminished by the existence of electronically active defects inside diamond such as secondary phases, bundles of dislocations and slip bands. In this paper, x-ray topography is compared with two dimensional responsivity mapping at various energies ranging from 300eV to 19keV to confirm the correlation between defects and responsivity of diamond photodiode. Energy dependent effects of diamond responsivity is discussed and possible mechanism is suggested.
12:15 PM - N14.4
Formation and Characterization of Boron-Doped Diamond Powders for Application in Energy Storage and Conversion Devices.
Greg Swain 1 , Doo Young Kim 1 , Liang Guo 1 , Ayten Ay 1 , Vernon Swope 1
1 Chemistry, Michigan State University, East Lansing, Michigan, United States
Show AbstractElectrically conducting diamond possesses some extraordinary properties that make it an ideal candidate electrode material for multiple electrochemical applications. Synthetic diamond is commonly prepared by CVD as a thin film on a suitable substrate or as a single crystal. However, these planar films are inadequate for applications that require high surface area. Powderous forms of electrically-conducting (extrinsic via doping) diamond possess the requisite high specific surface area. Our approach to preparing such nanoscale materials is to overcoat diamond abrasive, sp2 carbon powders or metal oxide powders with a thin layer of boron-doped ultrananocrystalline diamond (B-UNCD). This synthetic approach alters the functionality of the nanoscale substrate particles and imparts the excellent properties of diamond. This work constitutes an innovative approach to the synthesis/preparation of novel organic-organic and organic-inorganic composite materials with significantly improved structure, properties and function (e.g., electrical conductivity, high surface area, microstructural stability, corrosion resistance and biofouling resistance). We will report on the formation, characterization and basic electrochemical properties of these materials as they relate to applications in energy storage and conversion.
12:30 PM - N14.5
Advances in Doped Diamond Electron Emitters for Thermionic Energy Conversion.
Franz Koeck 1 , Jeff Sharp 2 , Robert Nemanich 1
1 , Arizona State University, Tempe, Arizona, United States, 2 , Marlow Industries, Inc., Dallas, Texas, United States
Show AbstractDirect conversion of heat into electricity presents means of providing compact, stand-alone power generators as well as waste heat recovery which increases overall systems efficiency. A vacuum thermionic energy converter utilizes an electron emitter separated from a collector by a vacuum gap. This thermal barrier can significantly increase device efficiency where operating temperature can be defined by controlling emission parameters, i.e work function and Richardson constant of the emitter. Our approach employs doped diamond thin films in a stacked structure prepared on a surface treated metallic substrate. This process accomplishes two critical results: a low effective work function and an increased value for Richardson's constant. Key component of the emitter is a nitrogen incorporated UNCD sub-layer which effectuates a low work function of the top, nitrogen - doped, NEA diamond layer. Additionally, diminished device resistance due to the network of high density, nitrogen incorporated, graphitic grain boundaries in the UNCD layer can establish an increased emission current density and its relation to Richardson's constant. While a theoretical approach quantifies this emission parameter at 120 A/cm2K2 a more accurate characterization can identify parameters which govern its effective value. We will present results from stacked, doped diamond emitters prepared by plasma assisted chemical vapor deposition on molybdenum substrates utilizing metallic interstitial layers to enhance device performance. Evaluation of the emitter with respect to the Richardson formalism presents a low work function of 1.2 eV and an effective Richardson constant of 16 A/cm2K2 corresponding to an emission current density of 7.7 mA/cm2 at 400 °C. Such reproducible devices approach an emission current density of 40 mA/cm2 at 500 °C. In a thermionic energy converter configuration the electron source is opposed from a similar collector by a vacuum gap. Conventional limitations due to space charge effects at the emitter are alleviated by our approach of surface ionization where gaseous species with suitable electron affinity are introduced into the interelectrode gap to enhance charge transfer between emitter and collector.This research was funded by the Office of Naval Research.
12:45 PM - N14.6
Nitrogen-Termination and AlN Depositon on Diamond.
Ryusuke Kanomata 1 , Daiki Utsunomiya 1 , Shunsuke Sato 1 , Shinichiro Kurihara 1 , Takuma Kobayashi 1 , Hidetoshi Tsuboi 1 , Atsushi Hiraiwa 1 , Hiroshi Kawarada 1
1 Nano-Science and Nano-Engineering, Waseda university, Tokyo Japan
Show AbstractSurface nitridation of diamond is one of the important surface modification methods which open a new field of application. For example, nitrogen-terminated diamond surface is a first step for synthesizing amino group termination for bioapplication or AlN hetero epitaxial growth on diamond[1]. In this way, nitrogen termination on diamond will be indispensable treatment for surface functionalization of diamond for development of carbon based electron devices in the future.
Our purpose in this research is the in-situ observation of nitridation of diamond surface by irradiating nitrogen radical beam in high vacuum to understand the nitridation process on diamond. In addition, we have tried to deposit AlN on diamond terminated by nitrogen, using RF plasma source MBE systm. AlN deposition on diamond by MBE has been already used in fabricating AlN-diamond pn-junction[2]. In this research, we aim to characterize the AlN deposition process by reflection high energy electron diffraction (RHEED) observation.
In this research, we synthesized nitrogen-termination on diamond surface by irradiating nitrogen radical beam formed RF (13.56MHz) excitation nitrogen plasma (RFN). Plasma emission spectroscopy clearly showed the peaks caused by nitrogen radicals, which are enhanced in the RF excitation source, not in the microwave plasma source. RFN radical beam was irradiated in the MBE deposition equipment. We synthesized nitrogen termination by irradiating radical beam on (111) or (100) single crystalline diamond, whose surface was already terminated by hydrogen or oxygen. The irradiation times and substrate temperatures were varied, and we researched correlations between these irradiation conditions and nitrogen-termination coverage. In parallel, we did in-situ observation of diamond surface during nitridation. We used RHEED for this surface characterization and state of diamond surface was evaluated by RHEED pattern. Coverage of nitrogen-termination was evaluated by XPS spectroscopy. We confirmed N1s peak in spectrum of wide scan, and C=N bond was mainly detecteded in CN bonds which exist on surface, from results of spectrum of narrow scan in C1s.
AlN was deposited by migration enhanced epitaxy (MEE) technique controlled by alternative supply of nitrogen radical and Al beam measured by fluxmonitor. Nitrogen radical beam source was RFN, and Al beam source was Al knudsen cell. AlN deposited on (111) single crystalline diamond to obtain (0001) single crystalline AlN. Crystallinity of AlN was estimated by in situ RHEED measurement. The first surface nitridation is crucial for the growth of AlN.
* This research was partially supported by Advanced Low Carbon Technology Research and Development Program.
Reference
[1] K.Hirama et al, J.Appl.Phys.108, 013528 (2010)
[2] C.R.Miskys et al, Appl.Phys.Lett.82, 2 (2003)