Symposium Organizers
Philippe Bergonzo CEA-LIST
Commissariat Energie Atomique (CEA/Saclay)
James E. Butler (Retired from Naval Research Laboratory)
Christoph E. Nebel Fraunhofer Institut fuer Angewandte Festkoerperphysik
Andrew T. S. Wee National University of Singapore
Milos Nesladek Hasselt University & IMEC vzw
A5: Poster Session: Diamond Electronics and Bioelectronics
Session Chairs
Tuesday AM, November 30, 2010
Exhibition Hall D (Hynes)
A1: Novel Imaging Approaches with Single Photon Sources
Session Chairs
Monday PM, November 29, 2010
Room 306 (Hynes)
9:30 AM - **A1.1
Nanoscopy With Focused Light.
Stefan Hell 1
1 Dept. of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Göttingen Germany
Show AbstractIt has been generally accepted that the resolution of a lens-based optical microscope is limited to about > 200 nm in the focal plane and > 500 nm along the optic axis, with NA denoting the numerical aperture of the lens and the wavelength of light. The discovery in the 1990’s that elementary transitions between the states of a fluorophore can be used to eliminate the limiting role of diffraction has led to light microscopy concepts with resolution on the nanometer scale. Currently, all existing and successfully applied nanoscopy methods share a common enabling element: they switch fluorescence on or off, so that adjacent features are registered sequentially in time.For example, in a typical Stimulated Emission Depletion (STED) microscope, the fluorophores are switched off (=kept dark) by overlapping the excitation beam with a de-exciting (STED) beam which effectively confines the fluorophores to the ground state everywhere in the focal region except at a tiny area where the STED beam is close to zero. Fluorophores that are located in this subdiffraction-sized smaller area are registered. Scanning the beams further in space registers those fluorophores that had been switched off. An image of the whole object is assembled by sequential registration. The resolution is now given by the smaller diameter d of this area in which the fluorophores are still fluorescent. I is the intensity of the STED beam, which, for I >> Is, entails d→0, meaning that the resolution is conceptually no longer limited by lamda.STED microscopy has been used to investigate the fate of synaptic vesicle proteins after exocytosis, thus demonstrating the potential of emerging ‘fluorescence nanoscopy’ for the life sciences. A video-rate STED microscope was used to describe the mobility of vesicles inside the axons of cultured living neurons. Live-cell STED microscopy has also been used to image activity-dependent morphological plasticity of dendritic spines, while in another study, it revealed that single sphingolipids, but not phospholipids, are transiently (< 10 ms) and locally (< 20 nm) trapped in a living cell membrane, mediated by cholesterol.The concept of STED microscopy has been expanded to low intensity operation by switching the fluorophore to a long-lived dark (triplet) state or between a ‘fluorescence activated’ and a ‘deactivated’ (conformational) state as encountered in switchable fluorescent proteins. More recent but seminal nanoscopy schemes such as PALM, STORM and also GSDIM, switch the molecules individually and stochastically to a state that emits m >>1 detectable photons in a row before returning to a dark state, allowing the calculation of their position. Altogether, lens-based optical nanoscopy is an unexpected and fascinating development in the physical sciences that is poised to impact several areas of science, in particular the life sciences, in the near future.
10:00 AM - A1.2
Photoluminescent Diamond Nanoparticles for Cellular Super-resolution Imaging.
Marie-Pierre Adam 1 , Yan-Kai Tzeng 2 1 , Jacques Botsoa 1 , Orestis Faklaris 2 , Hugues Girard 3 , Geraldine Dantelle 4 , Jean-Charles Arnault 3 , Michel Simonneau 5 , Huan-Cheng Chang 2 , Francois Treussart 1
1 Laboratoire de Photonique Quantique et Moléculaire, CNRS UMR 8537, Ecole Normale Supérieure de Cachan, Cachan France, 2 Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei Taiwan, 3 Diamond Sensor Laboratory, CEA-LIST, Gif-sur-Yvette France, 4 Laboratoire de la Matière Condensée, CNRS UMR 7643, Ecole Polytechnique, Palaiseau France, 5 Université Paris Descartes, INSERM U894, Centre de Psychiatrie et Neurosciences, Paris France
Show AbstractNitrogen-Vacancy (NV) color center in diamond has a perfectly stable photoluminescence in the red and near infrared spectral region.Diamond nanoparticles (size~20 nm) containing NV color centers (fluorescent NanoDiamonds, fNDs) are therefore perfectly suited for cellular and tissues imaging in this low absorption window, and for long-term tracking.We will show that fNDs are spontaneously internalized in different cell lines including primary neurons and do not induce cytotoxicity even at high concentrations.Thanks to NV center perfect photostability, fNDs are ideal for STimulated Emission Depletion Microscopy (STED) super-resolution microscopy which requires the combination of the fluorescence excitation by a usual Gaussian intensity shape beam (wavelength 532 nm) with the high power STED beam having a doughnut shaped intensity to stimulate the emission efficiently from the excited state (wavelength 735 nm). We will present preliminary observations of super-resolution imaging of fNDs in cells using cw lasers.Such super-resolution microscopy will be used in particular to image neuronal dendritic spines morphology, which disorders are associated to numerous neurodegenerative diseases.
10:15 AM - **A1.3
Imaging Magnetic Fields Using NV Centers in Diamond.
Amir Yacoby 1
1 , Harvard University, Cambridge, Massachusetts, United States
Show AbstractDetection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the biological and physical sciences. For example, at a distance of 10 nm, the spin of a single electron produces a magnetic field of about 1 micro Tesla, and the corresponding field from a single proton is a few nano Tesla. A sensor able to detect such magnetic fields with nanometer spatial resolution would enable powerful applications, ranging from the detection of magnetic resonance signals from individual electrons or nuclear spins in complex biological molecules to readout of classical or quantum bits of information encoded in an electron or nuclear spin memory. Recently we experimentally demonstrated an approach to such nanoscale magnetic sensing, using coherent manipulation of an individual electronic spin qubit associated with a nitrogen-vacancy impurity in diamond at room temperature. Using an ultra-pure diamond sample, we achieve detection of 30 nT magnetic fields at kilohertz frequencies after 1s of averaging. In this talk I will review some of the recent advances in the development of such a scanning magnetometer.
10:45 AM - A1.4
Optical Characterization of Diamond Nanoparticles on Transparent Thin Films and Their Applications.
Jennifer Choy 1 , Osman Bakr 1 2 , Thomas Babinec 1 , Birgit Hausmann 1 , Parag Deotare 1 , Marko Loncar 1
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Materials Science and Engineering, King Abdullah University of Science and Technology, Thuwal Saudi Arabia
Show AbstractChemically synthesized nanoparticles, such as fluorescent dyes and colloidal quantum dots, are commonly used as nanoprobes for biological and chemical sensing applications and single photon emitters in integrated optical devices. More recently, diamond nanoparticles (DNPs) have emerged as promising candidates for these applications, owing to their excellent physical and chemical properties, which include structural stability, chemical inertness, optical transparency, biocompatibility, and surface functionalizability. Additionally, DNPs can be made optically active by the host of color centers from defects in diamond that arise either naturally or via implantation. The fluorescence from DNPs is stable at room temperature and can have wavelengths from the green to the infrared. We present results on the optical characterization of size-controlled DNPs containing the nitrogen-vacancy (NV) defect center. DNPs from commercially obtained diamond slurries have been purified and size separated using analytical ultracentrifugation, resulting in narrow size distributions of ±13nm. As demonstration of their remarkable photo- and structural stabilities in chemical sensing applications, we have subjected the DNPs to harsh chemical and physical conditions, i.e. boiling in brine, and shown that their morphology, size distribution, and luminescence remain unchanged.Meanwhile, we propose the use of DNPs containing single NV centers as ideal single photon emitters for coupling to passive optical resonators fabricated in transparent thin films such as titania. We have designed high Q/V titania nanobeam cavities (with theoretical Q ~ 10^6 and V~0.4(λ/n)^3) that operate near the zero phonon line (637 nm) of the NV fluorescence and fabricated these structures in sputtered titania, using electron beam lithography and reactive ion etching. Finally, we have studied the optical and charge transfer dynamics of various nanoparticles integrated with titania thin films, by measuring the spectra and time traces of single emitter fluorescence using confocal microscopy. In contrast to CdSe/ZnS quantum dots, which exhibit photobleaching and blinking behavior with prolonged dark states that are consistent with the transfer of charges into the lower bandgap titania host matrix, fluorescence from DNPs are stable and non-blinking.
A2: Surface Chemistry: From Diamond to Nanodiamonds
Session Chairs
Monday PM, November 29, 2010
Room 306 (Hynes)
11:30 AM - A2.1
Chemical Reactivity of Diamond Surfaces.
Phillip John 1 , Michael Anderson 1 , John Wilson 1
1 School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh United Kingdom
Show AbstractDevelopment of the next generation of diamond devices for chemical and biological sensing requires techniques for surface modification under ambient conditions. Single crystal (100) substrates have been treated with a hydrogen plasma to maximise the (100) terrace width and produce high quality surfaces. Thermal oxidation, in dry O2, yielded monolayer oxygen coverage with a high proportion of 'on-top' (>C=O)oxygen.Covalent binding of 4-trifluoromethylbenzylamine, in solution at room temperature, to the surface carbonyl group was accomplished to form the water sensitive imine bond. Reductive animation created a water stable amine functional group on the diamond (100) surface.
11:45 AM - A2.2
Surface Chemistry Control and New Routes for Fast and Stable Functionalization of Nanodiamonds.
Hugues Girard 1 , Tristan Petit 1 , Sandrine Perruchas 2 , Jean Charles Arnault 1 , Philippe Bergonzo 1
1 Diamond Sensors Laboratory, CEA LIST, Gif sur Yvette France, 2 Laboratoire de Physique de la Matière Condensée, CNRS - Ecole Polytechnique, Palaiseau France
Show AbstractFluorescent diamond nanoparticles (fNDs) carrying nitrogen-vacancy (N-V) colored centers hold great promises for biomedical applications [1]. They combine some of the outstanding properties of bulk diamond, such as the chemical resilience or the carbon surface chemistry, as well as the benefits of a fluorescent center emitting in the far-red with an ultrahigh photostability [2]. Furthermore, their low cytotoxicity is reported [3] and their mass production is now well controlled [4].The use of fNDs to label biomolecules and track their fate in-vivo or to deliver bioactive molecules implies the addition of specific functionalities to the bare fNDs. Stability in biological media, targeting or drug-release mechanisms go through a surface functionalization of the particles with, e.g. PEG chains, proteins, ionic moieties... However, after post-synthesis purifications treatments and irradiation/annealing steps to create N-V centers, fNDs surface chemistry remains highly inhomogeneous, with amorphous carbon, graphite shells and various oxidized terminations. Here we report on the chemical preparation of NDs. Methods for surface homogenization by exposures to reactive atmospheres (plasma treatments, annealings) in order to rationalize the surface chemistry are detailed. Then, new functionalization routes are proposed as efficient ways to bind bioactive molecules on these pre-treated fNDs. The surface modifications of the NDs are characterized using X-ray Photoelectron Spectroscopy, Auger electron Spectroscopy, Fourier Transformed Infra-Red Spectroscopy, Dynamic Light Scattering and Zeta Potential measurements. By our preparation and grafting methods, novel surface properties are given to NDs, such as e.g. cationic sites, self-adhesive spots, useful for biomedical applications.[1]A. M. Schrand et al., Crit. Rev. Sol. State, 34 (2009) 18[2]S.-J. Yu et al., J. Am. Chem. Soc., 127 (2005) 17604[3]V. Vaijayanthimala et al., Nanotechnol., 20 (2009) 425103[4]Y.-R. Chang et al., Nanotechnol., 3 (2008) 284
12:00 PM - A2.3
Enhanced Reactivity of Diamond Nano-particles.
Oliver Williams 1 , Jakob Hees 1 , Christoph Nebel 1
1 Micro & Nano-sensors, Fraunhofer IAF, Freiburg Germany
Show AbstractNano-diamond particles obtained from the purification of detonation products are found tightly aggregated and with a diverse array of contaminants. This aggregation is due to sp2 carbon shells which are formed during the cooling cycle of the detonation shock wave. The de-aggregation of such material is difficult and various techniques have been proposed each with their relative merits and flaws. For example, milling techniques based on zirconia beads result in significant contamination while burning in air results in substantial material loss. In this work we present a complimentary technique based on the surface shell reactivity of these particles that has none of the above drawbacks.By heating detonation nano-diamond particles in hydrogen gas at 500 °C (10 mbar, 5 hours), we are able to produce mono-disperse colloids with particle sizes between 3-4 nm. The zeta potential of these colloids changes from negative for the untreated particles to positive for the treated material. The negative zeta potential originates from acidic groups on the untreated product that are displaced by hydrogen in the treated material. The change in zeta potential and particle size demonstrates that the particle surfaces are able to react with molecular hydrogen at relatively low temperatures. This is due to the sp2 nature of the surfaces which we have confirmed with TEM and analogous experiments on carbon black. Positive zeta potentials are a common feature of hydrogenated carbon black and larger diamond particles with less sp2 do not show this effect. Thus, we conclude that the effect is based on the sp2 nature of the detonation nano-diamond surfaces.
12:15 PM - A2.4
Predicted Site Dependence of the Binding Energies of Amino and Carboxylic Acid Groups on Diamond Nanoparticles: A New Route for Multi-functionalization.
Zachary Fitzgerald 1 , Natalie Gibson 1 , Tzy-Jiun Mark Luo 1 , Olga Shenderova 2 , Donald Brenner 1
1 Material Science, North Carolina State University, Raleigh, North Carolina, United States, 2 , International Technology Center, Research Triangle Park, North Carolina, United States
Show AbstractThe facile surface chemistry of diamond nanoparticles with a variety of different functional groups has made these systems attractive for many different applications in the materials and bio-medical sciences. To better understand and predict the covalent bonding of surface species to diamond nanoparticles, we have been using a semi-empirical electronic method to calculate surface binding energies for –NH2 and -COOH groups on hydrogen terminated 4.5 nm octahedral diamond nanoparticles as a function of binding site. The calculations predict that both functional groups prefer binding at apex sites, followed by edge and then terrace sites. For the amino group, the energy difference between bonding to an apex and edge site is ~0.3 eV, while the difference between the edge and terrace site is only ~0.1 eV. The energy difference between the apex and edge sites for the carboxylic acid group is also ~0.3 eV, but the energy difference between the edge and terrace site is ~0.7 eV. The differences in binding energies between the different sites are attributed to geometric effects that reduce steric repulsion between the functional groups and surface hydrogen for the apex and edge sites compared to the terrace sites. The larger difference in binding energy between the edge and terrace sites for the carboxylic acid compared to the amino group is attributed to the larger size of the former. This prediction of a relatively large dependence of binding energy on binding site suggests very different thermal lifetimes of these sites, and the possibility of using thermal cycling in different plasma environments to create nanoparticles with spatially heterogeneous chemical activity. Results of Monte Carlo simulations intended to test this hypothesis will be presented.
12:30 PM - A2.5
Nanodiamond Polymer Composites.
Ioannis Neitzel 1 , Mary Sullivan 2 , Vadym Mochalin 1 , Giuseppe Palmese 2 , Yury Gogotsi 1
1 Materials Engineering, Drexel University, Philadelphia, Pennsylvania, United States, 2 Chemical Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Show AbstractNanodiamond powder (ND) produced by detonation on an industrial scale is an attractive nanomaterial for reinforcing polymer matrices due to its superior mechanical, thermal and chemical properties. Composite materials are widely used for industrial and consumer applications ranging from the aerospace industry to electronic and biomedical applications. Specifically, desirable mechanical properties of the composite materials in combination with low specific weight can lead to an increased performance and fuel economy, which are major issues in the modern economy. Therefore, there exists an ongoing interest in creating composites which are stronger and lighter than pure polymers or metals. A careful selection of the composite components is of importance to achieve the desired properties. Nanodiamond is an excellent candidate for reinforcing polymer matrices due to its unique properties. Combined with a variety of chemical functionalizations, made possible due to a presence of a large number of functional groups on its surface, this material can be tailored to engineer new composites with enhanced mechanical properties. In this study, ND has been incorporated into an epoxy matrix. High concentration (up to 50%) ND samples have been produced using hot pressing and tested by depth sensing indentation with a spherical diamond indenter. An increase of up to 350% in Young’s modulus has been observed as well as an increase in hardness of up to 300% percent as compared to neat epoxy. Also, scratch tests show a significant increase in wear resistance of the composite were both piled-up and the amount of removed material have been reduced by 50%. Additionally thermal conductivity of ND epoxy samples with concentration of 30wt. % or higher has been improved. Both mechanical and thermal conductivity data suggest the formation of an interconnected network of ND particles. To further improve mechanical properties at low concentrations of ND, research on surface functionalization of ND is ongoing.
12:45 PM - A2.6
Surface Electronic Properties of Nanodiamonds.
Joseph Welch 1 , Aysha Chaudhary 1 , Mose Bevilacqua 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractThe electrical properties of as deposited mono-dispersed detonation nanodiamonds(DNDs) have been studied; a resistivity of the order of 1012 Ω/sq has beendetermined, with only one significant conduction pathway being observed. The dielectric character of the DND particles is also good, with dielectric loss tangent values in the range 0.05-0.5 being recorded. These combined observations suggest DNDs behave in electrical terms similar to thin film diamond, and that electrical applications for DNDs are worthy of pursuit. Since a simple room temperature sonication process has been used for their deposition, coating a wide-range of three dimensional substrate materials will be possible. A limitation on the electrical use the mono-dispersed DNDs, at least in the untreated, as-deposited from solution form used here, is the catastrophic loss of diamond-like character at temperatures above 400C. In contrast H-terminated NDs show greater stability and strongly modified electrical characteristics. The results be discussed in terms of the surface electrical characteristics of this interesting form of diamond.
A3: Progress in CVD Diamond Growth
Session Chairs
Monday PM, November 29, 2010
Room 306 (Hynes)
2:30 PM - **A3.1
Routes Towards Large Area, Low Pressure Nanodiamond Growth via Pulsed MW-linear Antenna Plasma-chemistry.
Michael Liehr 1 , Frantisek Fendrych 2 , Andy Taylor 2
1 , Leybold Optics GmbH, Alzenau, Siemensstrasse 88 D-63755, Germany, 2 , Institute of Physics, Academy Sciences of the Czech Republic, Praha 8 Czechia
Show AbstractCurrent experimental configurations for MW PECVD diamond growth do not allow simple up-scaling towards large areas, which is essential for microelectronic industries and other applications. Another important issue is the reduction of the substrate temperature during diamond growth to enhance the compatibility with wafer processing technologies. Such advantages are provided by MW-Linear Antenna (LA) plasma applicators, allowing a scalable concept for diamond growing plasmas. In the present work we introduce a novel construction of LA MW applicators designed for nanodiamond growth by using plasmas ranging from continuous wave (CW) to pulsed modes of high repetition rates (up to 20 kHz).Using fast pulsing provides several advantages for diamond growth. Firstly, it allows the application of high power in short pulses, leading to non-linear MW absorption and consequently a reduction of total average input power to ~ 5W/cm2 compared to ~ 20 W/cm2 for CW LA-MWs or to typically 100-200W /cm2 for resonance cavity applicators. Despite the factor of 50 power reduction, the diamond growth rate that can be obtained at 450°C is comparable to or higher than that of resonance cavity systems. Secondly, the pulsed plasma concept brings improvements in diamond quality when compared to the CW mode. The resulting diamond films, grown by pulsed plasma, show clean grain boundaries with columnar growth, i.e. resembling classical nano-crystalline diamond (NCD) films of high crystallinity. This is achieved by the use of a tailored plasma chemistry. In fact the concentration of atomic hydrogen can be sustained with sufficiently high values during the power-off periods at the right pulse frequency, while the growth rates in the off-period is significantly reduced. This allows suppression of re-nucleation during the growth and preparation of high quality NCD films with 2-5% sp2 carbon (based on Raman measurements), for layer thicknesses ranging from 30 to 300 nm. We show how diamond quality, measured by Raman spectroscopy and by ellipsometry depends on the MW pulse frequency and CH4/CO2/H2 gas ratios. The plasma conditions are monitored by OES spectroscopy and by using plasma probing to measure the electron fluxes and the electron energy distribution function. We demonstrate highly uniform diamond films grown on Si wafers with a homogeneity < 5% over an 8 inch area.
3:00 PM - A3.2
Simulations of CVD Diamond Film Growth Using a Kinetic Monte Carlo Model: Further Insights into the Diamond Growth Process.
Paul May 1 , Jeremy Harvey 1 , Neil Allan 1 , Yuri Mankelevich 2
1 School of Chemistry, University of Bristol, Bristol United Kingdom, 2 Skobel’tsyn Institute of Nuclear Physics, Moscow State University, Moscow Russian Federation
Show AbstractKinetic Monte Carlo (KMC) simulations of CVD diamond growth have been used to simulate 300 atomic layers of diamond growth. We have previously used this model to gain insight into the fundamental processes, including adsorption, surface migration, beta-scission and etching, that govern CVD diamond growth for a fixed set of deposition conditions. We now report new results obtained from using this model to predict the growth rates and morphology expected from gas phase conditions that experimentally give rise to single crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD) films. Despite its simplicity, the KMC model predicts growth rates and surface roughness values for each of the diamond types that are consistent with experimental observations. The relative rates of surface H abstraction and hopping determine the average surface diffusion length, λ, and (in the absence of defect formation and renucleation) this is a key parameter in controlling surface morphology. When the hopping rate is more than ~100× greater than the H abstraction rate, λ becomes <2, which means that migration is limited by the lack of availability of surface radical sites, and the migrating surface species simply hop back and forth between 2 adjacent sites but do not travel far beyond their initial adsorption site. Thus, Eley-Rideal processes dominate the growth, leading to the rough surfaces seen in NCD and UNCD. Conversely, when the hopping rate <100× higher than the H abstraction rate, migration occurs over greater distances (λ > 2), leading to Langmuir-Hinshelwood processes dominating the growth producing the smoother surfaces of MCD and SCD. By extrapolation, we predict that atomically smooth surfaces over large areas should occur once migrating species can travel ~5 sites (λ = 5), which requires a gas-phase concentration ratio of [H]/[CHx] > 13400 at the growing surface. Finally, the predictions for UNCD deposition in a microwave system were found to be anomalous compared to all the other growth conditions, probably as a result of carbonaceous particulates being created in the plasma which affect the gas chemistry in unknown ways.
3:15 PM - A3.3
Effect of Substrate Dislocations on Diamond Epilayer Devices Properties.
Thu Nhi Tran Thi 1 , Julien Pernot 1 , Franck Omnes 1 , Pierre Muret 1 , Etienne Gheeraert 1 , Bruno Fernandez 1 , Etienne Bustarret 1 , Jurgen Hartwig 2 , Francois Jomard 3 , Daniel Araujo 4
1 , Institut Néel, CNRS and Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 France, 2 , European Synchrotron Radiation Facility (ESRF), 38043 Grenoble Cedex 9 France, 3 , GEMaC –CNRS Université de Versailles , BSaint-Quentin F-92195 Meudon Cedex France, 4 , Departamento de Ciencia de los Materiales e IM y QI, Universidad de Cadiz, 11510 Puerto Rea Spain
Show AbstractOne (100) Ib HPHT substrate of 3x3mm2 was selected among 30 substrates checked by different methods such as mis-orientation, optical profiling and AFM for surface quality and bi-refringence optical microscopy and X-ray topography images for bulk quality. By optimizing MPCVD growth conditions using oxygen in the gas phase, we were able to obtain a very low boron doped layer with a smooth surface. The RMS roughness was ~2nm, similar to the substrate before growth.
Different Hall bars were fabricated on different areas on the sample in order to determine the location of defects (which come from the substrate) influencing to the devices. The high hole mobility, measured by the Hall effect, is 1250cm2/Vs at 300K, close to the highest value reported. From fitting the neutrality equation, we deduce the low boron doping level to be 5×1016cm-3 and that there is a low contribution of scattered ionized impurities around room temperature due to the low compensation. Various mobility and resistivity parameters showed inhomogeneous electrical properties. The low mobility regions of the sample correlated with high dislocation density regions as measured by X-Ray topography and high band A luminescence mapping via CL. The TEM revealed more details about the types of defect as well as their density.
In the less defective regions of the same sample (as shown by XRay topography), in order to investigate the reproducibility of Schottky diodes, we fabricated a number of planar diodes. We used two different methods to fabricate diodes: the classic ring-shape performed by O2 microwave plasma with Al contacts and the more recent method performed by ozone treatment and with Au contacts. The I(V) and C(V) characteristics showed no dependence on the treatments but rather on the dislocations density. By I(V) measurements, a forward current density of 3×10-3 A/cm2 and a reverse current density of 5x10-5 A/cm2 at ±10V are observed. The doping profiles deduced from C(V) data of these diodes give the boron concentrations in the range of 3 to 5×1016 cm-3 for all the diodes, compatible with the value of 1.3×1016 cm-3 found from the bound exciton relative intensity obtained by CL measurements and 2 to 3×1016 cm-3 obtained from SIMS measurements.
All these results confirm our success in growing homoepitaxial lightly boron doped diamond layer with its interesting electrical properties. We were able to control a low boron doping level using oxygen during MPCVD. Due to this low doping level, the electrical properties of the epilayer are sensitive to non-homogeneity of defects. The effects of dislocation in the substrate and of growth defects on device properties will be discussed in particular.
3:30 PM - A3.4
Carrier lifetime, Diffusion Length and Mobility in (100) CVD Diamond Samples Pre-treated in an O2/H2-plasma.
Wim Deferme 1 , Ken Haenen 1 2 , Milos Nesladek 1 2 , Tadas Malinauskas 3 , Kestutis Jarasiunas 3
1 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 2 IMEC vzw, Division IMOMEC, Diepenbeek Belgium, 3 Institute of Applied Research, Vilnius University, Vilnius Lithuania
Show AbstractGreat advances in the deposition of high-quality homoepitaxial diamond and their commercial availability make this material interesting for detector and device applications. An important aspect of the growth is the diamond quality improvement with the thickness, related to the coalescence of individual growth sectors and the suppression of the propagation of some dislocations in the initial stage of the growth. Hence, it is interesting to know how defects (intrinsic and extrinsic) related to the initial stage of the growth influence the charge carrier parameters – their mobility and lifetime.In this work, samples are first pre-treated in an O2/H2-plasma for different times influencing the occurence of defects like unepitaxial crystals, hillocks with flat top and pyramidal hillocks at the surface after growth of 100-500μm thick diamond layers [1,2]. While the surface is studied by SEM and AFM, LITG (Light Induced Transient Grating Technique) and ToF (Time-of-Flight) studies will give information on the carrier lifetime, diffusion length and mobility of the grown layers [3,4]. It is shown that after an O2/H2-plasma treatment of more than 3 hours, the incorporation of defects in the bulk of the grown diamond is largely reduced, which influences the carrier dynamics measured by LITG and ToF. Also the surface roughness and the growth rate are influenced by the O2/H2-plasma pre-treatment as is shown by SEM and AFM. [1] J. Achard, F. Silva, O. Brinza, X. Bonnin, V. Mille, R. Issaoui, M. Kasu, A. Gicquel, phys. stat. sol. (a) 206/9 (2009), 1949[2] G. Bogdan, M. Nesládek, J. D’Haen, J. Maes, V.V. Moshchalkov, K. Haenen, M. D’Olieslaeger, phys. status solidi (a) 202/11 (2005), 2066[3] T. Malinauskas, K. Jarasiunas, E. Ivakin, V. Ralchenko, A. Gontar, S. Ivakhnenko, Diamond Rel. Mater. 17 (2008), 1212[4] W. Deferme, A. Bogdan, G. Bogdan, K. Haenen, W. De Ceuninck, M. Nesládek, phys. stat. sol. (a) 204/9 (2007), 3017
A4: Carbon Structure: From Graphene to Diamondoids
Session Chairs
Monday PM, November 29, 2010
Room 306 (Hynes)
4:15 PM - **A4.1
Electrical Properties of the Diamond-graphene Interface.
Kian Ping Loh 1 , Priscilla Kai Lian Ang 1
1 Chemistry, National University of Singapore, Singapore Singapore
Show AbstractGraphene is a metallic conductor and diamond is an insulator. The marriage of the two materials at the interface creates interesting chemistry. In this talk, i will discuss how graphene can be transfered onto nominally undoped diamond surfaces that have been pre-treated differently (eg. H-plasma treated, O-plasma, molecular wire-coupled and UV-treated), focusing on the charge transfer and field effect mobility of the graphene on the diamond. It is found that depending on the surface terminations on diamond, the residual impurities and mobility on graphene is affected. The mechanical robustness of the graphene which is transfered to diamond is enhanced signifcantly, compared to silicon, when subjected to sonochemical agitation.
4:45 PM - **A4.2
Raman Spectroscopy as a Probe of Carbon Materials.
Mildred Dresselhaus 1
1 EECS and Physics, MIT, Cambridge, Massachusetts, United States
Show AbstractRaman Spectroscopy has been used for several decades as a probe for the structure and properties of the various types of carbon materials including both sp3 diamond materials and sp2 planar carbon materials. We include here a discussion of nanostructured forms like nanodiamond, nanotubes, fullerenes, and graphene-like materials. Insights into our present knowledge of the field and open issues remaining for future work will be discussed, including views about the use of spectroscopy to gain insights into newly discovered carbon materials, their structures and common defects.
5:15 PM - A4.3
Thermal Effects on the Raman Spectra of Diamond Nanoparticles.
Marc Chaigneau 1 , Hugues Girard 2 3 , Jean-Charles Arnault 2 , Razvigor Ossikovski 1
1 Laboratory of Physics of Interfaces and Thin Films, Ecole Polytechnique, Palaiseau France, 2 Diamond Sensors Laboratory, CEA LIST, Gif-sur-Yvette France, 3 Condensed Matter Physics Laboratory, Ecole Polytechnique, Palaiseau France
Show AbstractThe Raman spectra of diamond nanoparticles (NDs) exhibit a characteristic carbon-sp3 phonon peak that is broadened and down-shifted with respect to that of bulk diamond located at 1332 cm-1. We report on the temperature effects on the Raman spectra of NDs produced either by detonation synthesis or by milling of high-pressure high-temperature (HPHT) diamond. Moreover, different mean diameters (ranging from 3 nm to 50 nm) were investigated. In particular, we show that the behaviour of the carbon-sp3 peak is more consistent with the temperature increase of NDs due to the local heating caused by the laser (at 458 nm) rather than with the phonon confinement model alone widely used for nanoparticles spectra interpretation in the literature [1-3]. Local temperatures as high as 700 K are reached as confirmed by the anti-Stokes spectra. We use a Fano-resonance model, modified to account for the nanoparticle mean size and combined with the Klemens model for the temperature effect, to fit the experimental first-order Raman spectrum. We further show that the phonon behaviour with temperature also depends on the synthesis method (detonation or HPHT) and the NDs mean size. Furthermore, the thermal behaviour of the broad Raman band in the 1500-1700 cm-1 range is likewise dependent on the synthesis method used. Eventually, the reversibility of the thermally-induced phonon shift can be used to distinguish between the presence of sp2 clusters and that of surface hydroxyl groups in the nanoparticles.[1] M. Yoshikawa, Y. Mori, M. Maegawa, G. Katagiri, H. Ishida, A. Ishitani, Appl. Phys. Lett. 62, 3114 (1993).[2] J. W. Ager III, D. K. Veirs, G. M. Rosenblatt, Phys. Review B 43, 6491 (1991).[3] K. W. Sun, J. Y. Wang, T. Y. Ko, Appl. Phys. Lett. 92, 153115 (2008).
5:30 PM - A4.4
Local Stress-strain Structure at Dislocation in CVD Diamond Observed by Raman Peak-shift Mapping.
Yukako Kato 1 , Hitoshi Umezawa 1 , Hirotaka Yamaguchi 2 , Shinichi Shikata 1
1 Diamond Research Laboratory, Advanced Industrial Science and Technology (AIST), Tsukuba Japan, 2 Nanoelectronics Research Institute, Advanced Industrial Science and Technology (AIST), Tsukuba Japan
Show Abstract Diamond has attracted much attention due to the parameter for the high power device application. Because diamond has a wide band gap, high breakdown field, high thermal conductivity, it is expected to be a material using Schottky barrier diode [1, 2] as the high breakdown voltage and high temperature operation devices. For the development of that diamond device, the study on defects in respect to the device characteristics [3] is the most important topic for this consideration. However, the study covered this topic is not enough for the general discussion. In our presentation, it is shown that the raman microscopic peak-shift mapping as the experimental data of the local stress-strain at the dislocation in CVD diamond. The dislocation position is decided by the synchrotron x-ray topographies, Cross-Nicole images and Cathodoluminescence mapping. The sample is epitaxial diamond film. It was deposited on HPHT Ib(100) substrates by microwave plasma CVD method. Raman spectra and peak-shift map were recorded by using raman microscope, HR800 (Horiba Jobin-Yvon), with 633 nm excitation. From the peak-shift mapping around the dislocation, the stress-strain structure was observed. Cross-sectional peak-shift mapping at same area is shown the dislocation. Its grown direction is along <111>. Because of this observation, we suggest that this is the edge dislocation. From the luminescence mapping, it is shown that the observed dislocation and others are on one side of color zoning. This zoning is derived from the cubic or octahedral growth structure of CVD diamond.Acknowledgment:The New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry of Japan financially supported this study. The x-ray topography experiment was performed under approval of the Photon Factory Advisory Committee (Proposal No. 2010G168). We thank Dr. T. Teraji(NIMS) for the measurement of CL mapping and valuable discussions.Reference:[1] “Leakage current analysis of diamond Schottky barrier diode," H. Umezawa, T. Saito, N. Tokuda, M. Ogura, S. G. Ri, H. Yoshikawa, S. Shikata, Appl. Phys. Lett. 90, 73506 (2007).[2] “Diamond low-leakage Schottky barrier diode,” H. Umezawa, K. Ikeda, N. Tatsumi, S. Shikata, Proceedings of ICSCRM 2007, We-P-81.[3] “Reduction of epitaxial defects in diamond for high power device,” N. Tatsumi, H. Umezawa, S. Shikata, Proceedings of ICSCRM 2007, Th-P-33.
5:45 PM - A4.5
Ultra-low Charge Injection Barrier in Diamondoid Molecular Electronic Devices.
Jason Fabbri 1 , Nazanin Davani 1 , Peter Schreiner 2 , Jeremy Dahl 1 , Nicholas Melosh 1
1 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States, 2 Institute of Organic Chemistry, Justus-Liebig University, Giessen Germany
Show AbstractRecently isolated higher diamondoids are 1-2 nm diamond molecules. They are in the size range where quantum confinement effects are expected to occur and they can be easily assembled into diamond nanoelectronic devices. We obtain the diamondoids in high purity through isolation from petroleum. Hydrogen surface passivation allows for site specific functionalization with thiols, amines, etc. Here we present transition voltage spectroscopy characterization of the electrical properties of diamondoid-thiol monolayer junctions. We find a 0.3 eV barrier for hole charge carrier injection from the gold electrode into the diamond molecules. This is the lowest value yet observed in the gold/thiol self-assembled monolayer system commonly employed in molecular electronics. Applications to light emitting diodes and electron emission devices will be discussed. We use three testing platforms to verify our result – conducting probe AFM, cross-wire junctions, and large-area lift-on junctions along with DFT simulations and ultraviolet photoelectron spectroscopy characterization. We extend the work to monolayers of diamondoid thiols on silver and diamondoid alkenes and silanes on silicon to suggest how the unique electronic properties and interactions of diamond molecules can be used to create high performance devices.
A5: Poster Session: Diamond Electronics and Bioelectronics
Session Chairs
Tuesday AM, November 30, 2010
Exhibition Hall D (Hynes)
9:00 PM - A5.1
Defect States in Irradiated Boron-doped Diamond Films Investigated Using Surface Photovoltage and Photoluminescence Spectroscopy.
Sanju Gupta 1 , R. Peters 2 , J. Paramo 2 , J. Farmer 3 , Y. Strzhemechny 2
1 Chemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 Physics and Astronomy, Texas Christian University, Dallas Fort Worth, Texas, United States, 3 MURR and Physics, University of Missouri, Columbia, Missouri, United States
Show AbstractReliability, quantification and qualification are the crucial issues holding back diamond as an engineering material from playing a larger role in harsh environment applications. In general, diamond is known for being more radiation-hard than common mature semiconductors (e.g. Si, GaAs and AlGaN). For applications such as deep UV photodiode (alternatively, visible blind), medical radiotherapy and novel nuclear micro-battery, it is critical to demonstrate material’s structural integrity and physical stability. The present work is driven by our recent reports [Gupta et al. J. Mater. Res. 24 (2009); ibid. 25 (2010)], where we carried out detailed investigations on the effects of boron doping and gamma irradiation on boron-doped diamond (BDD) films grown by microwave plasma-assisted chemical vapor deposition. We demonstrated the role of point defects induced by gamma irradiation in BDD films (grown with [B]/[C]gas = 4000 ppm that translates to boron concentration of > 1020 cm-3 in the films), which transforms the quasi-metallic to semiconducting nature facilitated by passivation of electrically active boron via hydrogen migration. Though boron as an impurity brings a complexity, it makes diamond either a lightly doped or a degenerate semiconductor depending upon the level of doping. The present work employs among others surface photovoltage (SPV) spectroscopy providing a further insight into the identification of conduction versus valence band nature of the defect-related transitions and the defect level positions within the band gap, as well as the ability to measure relatively low densities of surface states. While we did not observe any prominent spectral feature for the pristine BDD sample, there are several major spectral features for the gamma-irradiated samples. SPV sub-band-gap transitions were observed to occur at 1.2, 1.3, 1.5 eV from valence and 1.25, 1.4, 1.8 and 2.1 eV from conduction band. It is quite plausible that the transitions can be attributed to the top boron-doped diamond layer (thickness ~ 200 nm) and they refer with respect to the corresponding electronic bands in a semiconducting material. Likewise, we have also employed temperature-dependent photoluminescence spectroscopy to assess radiation-induced lattice/point defects and observed point defect GR1 center peak at 1.68 eV, B-related band at 2.3 eV and intrinsic defect (5RL center) band at 2.91 eV. These results will be discussed in light of the radiation-induced structural modification in an otherwise known radiation-tolerant diamond films for nuclear micro-battery. The author (SG) acknowledges O. Williams and K. Haenen (IMR-Belgium) and P. W. May (Bristol University, UK) for some of the BDD samples.
9:00 PM - A5.11
Detection of Melittin Induced Distruptions of Supported Lipid Bilayers on Boron Doped Nanocrystalline Diamond Film.
Vaclav Petrak 1 2 , Lars Grieten 4 , Andrew Taylor 2 , Frantisek Fendrych 2 , Miroslav Ledvina 3 , Patrick Wagner 4 , Milos Nesladek 4
1 Faculty of Biomedical Engineering, Czech Technical University, Kladno Czechia, 2 , Institute of Physisc AS CR, Prague Czechia, 4 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 3 Gilead Sciences and IOCB Research Center, Institute of Organic Chemistry and Biochemistry AS CR, v.v.i., Prague Czechia
Show AbstractSubstrate-supported lipid bilayers (SLBs) are commonly used as a model of cell membranes for biotechnological applications and scientific research. They are composed essentially of a phospholipid bilayer membrane absorbed on the surface and can serve as sensory elements for lipid-bilayer based sensors. [1]In this work, we study a self-assembly and subsequent disruption of supported lipid bilayers on a boron doped nanocrystlline diamond film (B-NCD) by impedance spectroscopy.B-NCD films were grown in a plasma enhanced chemical vapor deposition (PECVD) reactor, which allows for the deposition of films of low surface roughness. Neutral dioleoyl-phosphatidylcholine (DOPC) and negatively charged dioleoyl-phosphatidylserine/dioleoyl-phosphatidyl-choline (20% DOPS/80% DOPC) vesicles for SLB self-assembly were prepared by sonication and a SLB was formed on the the surface of B NCD via the fusion of liposomes method. Formation of a SLB was monitored by confocal fluorescence microscopy and impedance spectroscopy. Melittin and phospholipase 2 (PLA2) were used as membrane disruptive agents.Impedance spectroscopy as well as confocal microscopy confirmed succesfull formation of a SLB on the surface of B-NCD, which remained present on the surface after flushing of redundant liposome. Mellitin and PLA2 induced a change of impedance characteristic when introduced into measurement chamber. We discuss suitability of impedance spectroscopy as a tool for the investigation of the effect of Melittin and PLA2 on the SLB integrity. We further discuss biosensing properties and limitations of a lipid membrane as sensory element on B NCD.[1] E T Castellana and P S Cremer."Solid supported lipid bilayers: From biophysical studies to sensor design." Surface Science Reports. 61. (2006) 429-444.
9:00 PM - A5.12
Ionic Strength as a Driving Force of Nanodiamond Aggregation in Aqueous Solution.
Vaclav Petrak 1 2 , Petr Cigler 3 , Miroslav Ledvina 3 , Vladimira Rezacova 1 2 , Josef Masek 4 , Jaroslav Turanek 4 5 , Stoffel Janssens 6 , Ken Haenen 6 , Milos Nesladek 6 7
1 Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno Czechia, 2 Department of Functional Materials, Institute of Physisc AS CR, Praha 8 Czechia, 3 Gilead Sciences and IOCB Research Center, Institute of Organic Chemistry and Biochemistry AS CR, v.v.i., , Prague Czechia, 4 , Veterinary Research Institute, Brno Czechia, 5 , South Bohemia University, Ceske Budejovice Czechia, 6 Institute for Materials Research (IMO), Hasselt University, Diepenbeek Belgium, 7 Division IMOMEC, IMEC vzw, Diepenbeek Belgium
Show AbstractNanodiamonds (ND) have gained attention of a wide scientific audience due to their inexpensive large-scale synthesis an interesting application in biological and medical sciences for tracking, based on nitrogen-vacancy centre (NV) luminescence.In biological and medical application it is essential to prepare ND fully dispersed in aqueous solutions containing dissolved salts and ionic substances. This is especially true for application of ND as a biomarker to physiological solution where it is very important to prevent clustering.In this study we show the influence of ionic characteristics of dispersion on aggregation of ND and their corresponding ζ potential. Several types of commercially available ND particles were used in this study in native and functionalized form. Particles were deagglomerated by sonication prior diluting in aqueous solutions of various pH and ionic characteristics. The size of ND was evaluated by dynamical light scattering (DLS) and ζ potential was measured. The surface termination was controlled from H-ND to OH, O, F and other functional groups.The particles exhibited a strong tendency towards aggregation in aqueous environments outside a limited range of pH values. Aggregation of ND was also found to be occurring in the presence of ionic substances. The degree of aggregation was proportional to the ionic strength of the solution and was different for various commercial ND. The important factor controlling the agglomeration was the surface termination, influencing ζ potential and ND stability in various solutions.
9:00 PM - A5.13
Production of a High Density of NV- Centers in HPHT Type 1b Bulk Diamond.
Jacques Botsoa 1 2 , Thierry Sauvage 1 , Pierre Desgardin 1 , Elisa Leoni 1 , Francois Treussart 2 , Marie-France Barthe 1
1 Conditions Extrêmes et Matériaux : Haute Température et Irradiation, CNRS UPR 3079, Orléans France, 2 Laboratoire de Photonique Quantique et Moléculaire, UMR 8537 CNRS ENS Cachan, Cachan France
Show AbstractIn diamond, high-density ensembles of the negatively charged nitrogen-vacancy (NV-) color center in diamond is promising for applications such as ultrasensitive magnetometry which relies on the optical detection of the NV- electron spin resonance.For this purpose, the optimization and adequate control of the formation of NV- ensembles are needed. So, we have studied the optimal conditions to produce NV- ensembles by the route of proton irradiation for vacancy creation followed by annealing under vacuum of the diamond sample. Attention has particularly been paid to the influence of proton fluence on vacancy creation, as well as annealing temperature and duration. Several HPHT type 1b diamond samples from Element 6 have been irradiated with 2.4 MeV protons at fluences ranging from 1×1012 at/cm2 to 1×1017 at/cm2, annealed under vacuum at temperatures ranging from 600°C to 1000°C during times varying from 1h to 20h. Each sample has been characterized at different stages of the NV- formation process (before irradiation, after irradiation and after annealing) by Slow Positron Beam based Doppler annihilation-ray Broadening (SPBDB) spectrometry and confocal photoluminescence (PL) spectroscopy. SPBDB shows that before annealing, and at low proton fluence, the formation of monovacancy defects is observed, while at higher fluences, a new vacancy related defect appears. After annealing, SPBDB shows the formation of a new defect, identified as the NV- center also observed by PL. NV- concentration has been estimated from PL intensity, using single NV- PL intensity as the reference. Concentrations up to 14 ppm have been measured in the best samples corresponding to a N→NV conversion efficiency of about 4%. Moreover, infrared absorption measurements carried out on non-annealed samples highlight the discrepancy between vacancy concentration and Stopping and Range of Ions in Matter (SRIM) simulations. The influence of proton fluence and of annealing time and temperature will be discussed.
9:00 PM - A5.14
Nanostructured Diamond-like Carbon Films Formation by Thermionic Vacuum Arc Method.
Ana Mihaela Lungu 1 , Aurelian Marcu 1 , Ionut Jepu 1 , Corneliu Porosnicu 1 , Cristian Lungu 1 , Cristiana Grigorescu 2
1 Plasma Physics, NILPRP, Magurele-Bucharest Romania, 2 Material Characterization, INOE 2000, Magurele-Bucharest Romania
Show AbstractNanostructured diamond-like carbon films have been deposited from the pure vapor carbon plasma using an original thermionic vacuum arc method [1]. Silicon single crystalline wafers and germanium plates held at 400oC were used for substrates. The influence of the main process parameters (discharge voltage and the intensity of the tungsten filament providing the electron beam) to the films’ characteristics was investigated by different techniques such as HRTEM, SAED, XPS and Raman spectroscopy. The films consist of complex 2-10 nm nanodiamond particles embedded in an amorphous carbon matrix. XPS measurements showed more than 60% sp3 over the coexiting sp2 and sp1 chemical bonds. The Raman scattering measurements have shown characteristic D (disorder band) and G (C-C stretching in the graphite plane) modes of carbon in all samples, with a ratio of the integral intensities varying with the deposition parameters with an optimal value for samples produced with 600 eV ions. In addition to the G and D modes, a feeble Raman feature was observed in the low frequency range of the spectra, i.e. between 150 and 250 cm-1 in the samples deposited at ion energies around 800 eV. This feature was remarked in carbon nanotube-like structures and its characteristic frequency is related to the nano-dimension of the crystallites embedded in the disordered carbon phase. Protective and antireflex coatings based on the prepared films were applied on a wide range of optical components as well as on tungsten substrates in order to simulate the erosion product deposition and fuel retention after a fusion experiment campaign. [1] C. P. Lungu, I. Mustata, G. Musa, V. Zaroschi, Ana Mihaela Lungu and K. Iwasaki: Low friction silver-DLC coatings prepared by thermionic vacuum arc method, Vacuum, 76, Issues 2-3, 127-130, (2004)
9:00 PM - A5.15
Determination of Boron Concentration in Doped Diamond Films.
Shannon Demlow 1 , T. Grotjohn 1 2 , D. Reinhard 1 2 , M. Becker 2 , J. Asmussen 1 2
1 Electrical and Computer Engineering (ECE), Michigan State University, East Lansing, Michigan, United States, 2 , Fraunhofer Center for Coatings and Laser Applications, East Lansing, Michigan, United States
Show AbstractDiamond’s exceptional properties, such as a wide bandgap, high breakdown voltage, and high electron and hole mobilities, make it a potentially useful semiconductor for high-temperature and high-power devices. Boron-doped p-type diamond has applications for the fabrication of electrodes for electrochemistry and electronic devices such Schottky-barrier diodes and metal-semiconductor field effect transistors. The realization of useful devices requires the deposition of high quality, controlled conductivity films. Our previous work1,2 on the deposition of high-quality boron-doped single crystal diamond (SCD) measured the growth rates of boron-doped films as a function of the concentration of diborane and methane in the feedgas with the aim of increasing the growth rate and the quality of the films. Previous work3,4 on the characterization of the electrical properties of films utilized infrared absorption techniques and temperature dependant conductivity measurements performed using a four point probe.This work expands upon the previous effort to grow and characterize high quality boron-doped diamond films. Films are deposited on HPHT SCD substrates using a microwave plasma-assisted CVD reactor with hydrogen, methane and diborane in the feedgas mixtures. Boron-doped diamond films are grown over several orders of magnitude of boron concentrations. Experimental results obtained for electrical conductivity measured with a four-point probe, IR absorption data measured with FTIR, and boron concentration measured with SIMS are analyzed toward the aim of developing reliable calibrations for the determination of boron concentration in diamond films. Temperature dependant conductivity data is analyzed to determine dopant activation energies, and sample preparation methods such as cleaning and annealing steps are examined to determine and control surface and near surface conduction and dopant activation properties.References1. R. Ramamurti, M. Becker, T. Schuelke, T.A. Grotjohn, D. K. Reinhard and J. Asmussen, Diamond & Related Materials, Vol. 17, pp. 1320-1323, (2008)2. R. Ramamurti, M. Becker, T. Schuelke, T.A. Grotjohn, D.K. Reinhard and J. Asmussen, Diamond & Related Materials, Vol. 18, pp. 704-706, (2009)3. S.S. Nicley (S.N. Demlow), D. Tran, C. Fansler, D.K. Reinhard, T.A. Grotjohn, J. Liebich, C. Pieper, M. Becker, J. Asmussen, Presented at the New Diamond and Nano Carbons Conference, June 7-11 2009, Traverse City, MI4. T.A. Grotjohn, S.S. Nicley (S.N. Demlow), D. Tran, D.K. Reinhard, M. Becker, J. Asmussen, Conference Proceeding, 2009 MRS Fall Meeting, Boston, MA Nov 30- Dec 4 2009. Paper #: 1203-J17-17
9:00 PM - A5.16
Thermal and Electrical Conduction Properties of Nanocrystalline Diamond/Amorphous Carbon Composite Films.
Kungen Teii 1 , Tomohiro Ikeda 1
1 , Kyushu University, Kasuga, Fukuoka Japan
Show Abstract The performance of silicon-based electronic devices is more and more approaching their upper temperature limit when they are applied to high-temperature and high-power electronics, which is essential for hybrid and electric vehicles. It is necessary to radiate extra heat efficiently through a heat sink (typically made of aluminum) coated with a heat-resistant material with high thermal conductivity. 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 - A5.17
A Diamond Film-based Beta Radiation Sensor.
Javier Morales 1 5 , R. Bernal 2 , C. Cruz-Vazquez 3 , J. Almaguer 4 , V. M. Castano 5
1 Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autonoma de Nuevo leon, San Nicolas de los Garza, Nuevo Leon, Mexico, 5 Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Queretaro, Queretaro, Mexico, 2 Departamento de Investigacion en Fisica, Universidad de Sonora, Hermosillo, Sonora, Mexico, 3 Departamento de Investigacion en Polimeros y Materiales, Universidad de Sonora, Hermosillo, Sonora, Mexico, 4 Facultad de Ciencias Fisico matematicas, Universidad Autonoma de Nuevo Leon, San Nicolas, Nuevo Leon, Mexico
Show AbstractDiamond films exhibits excellent properties as high heat conductivity and low electrical conductivity, due to phonon phenomena. Also, its strong valence bonds allow gap values up to 5.4 ev. When diamond films are exposed to beta radiation, some electrons pass from the valence to the conduction band, in this new energetic state the diamond properties are different, the changes in electrical properties are more significant than the thermal ones. The goal in this work is to estimate the variations of the electrical conductivity as a function of beta radiation dose and temperature, based on thermoluminescence experimental data, aiming to use diamond thin films as beta radiation sensor.
9:00 PM - A5.18
Homoepitaxial Growth of High Quality Thick Diamond Film with Microwave Plasma CVD Technique.
Hong-Xing Wang 1 , Noritaka Ishigaki 1 , Toshiki Ohkawa 1 , Shinichi Kokami 1 , Hideo Inoue 1 , Ryuuichi Terajima 1 , Katsuhiko Mutoh 1 , Toshiro Kotaki 2
1 , R&D, Diamond CVD Systems Department,Seki Technotron Corp., Tokyo, Tokyo, Japan, 2 , NJC Institute of Technology, Namiki Precision Jewel Co. Ltd., Tokyo, Tokyo, Japan
Show AbstractDiamond film collects all the outstanding properties of mechanics, electronics, heat, and optics etc. together making it have potential applications in the fields of wide range optical transparent window material, super-hard coating tools, espically, in the field of high power electron devices which can work with high frequency and in high temperature environment. This encouraged researchers to extensively investigate the synthesis techniques to develop large area single crystal diamond substrate and high quality homoepitaxial diamond film. Recently, it is reported that high quality diamond films have been grown with several range methane concentration, resulting in a device-grade diamond film, by which some devices have been developed[1,2]. However, most of these results have been achieved using microwave plasma chemical vapor deposition(MPCVD) system with an end-launch (vertical) type chamber. There are few reports about the growth of high quality diamond film by MPCVD with the over-mode (horizontal) type chamber. Also, some of the un-doped single crystal diamond growth techniques are still unclear.In this study, we report a growth of high quality thick diamond film on high pressure and high temperature diamond substrate by microwave plasma chemical vapor deposition system with the over-mode (horizontal) type chamber. First, the effect of growth parameters on the growth film morphologies was investigated, indicating that the diamond film is very sensitive to the growth temperature and input microwave power. Then, different configurations of sample holders were used in our experiment, illustrating that high quality diamond film can be grown by using the sample holder with smooth surface. Finally, the as grown samples were characterized by Raman spectroscopy, x-ray diffraction, cathodeluminescence, and photoluminescence techniques.[1] H. Okushi, H. Watanabe, S. Ri, S. Yamanaka, D. Takeuchi, J. Cryst. Growth 2002, 237-239, 1269.[2] Tokuyuki Teraji, Toshimichi Ito, J. Cryst. Growth 2004, 271, 409.
9:00 PM - A5.19
VD Diamond Dislocations Observed by X-ray Topography, Cross-nicole Image and Cathodoluminesence Mapping.
Yukako Kato 1 , Hitoshi Umezawa 1 , Hirotaka Yamaguchi 2 , Shinichi Shikata 1
1 Diamond Research Laboratory, Advanced Industrial Science and Technology (AIST), Tsukuba Japan, 2 Nanoelectronics Research Institute, Advanced Industrial Science and Technology (AIST), Tsukuba Japan
Show Abstract Diamond has attracted much attention due to the parameter for the high power device application. Because diamond has a wide band gap, high breakdown field, high thermal conductivity, it is expected to be a material using Schottky barrier diode [1, 2] as the high breakdown voltage and high temperature operation devices. For the development of that diamond device, the study on defects in respect to the device characteristics [3] is the most important topic for this consideration. However, the study covered this topic is not enough for the general discussion. In our presentation, defects in CVD diamond are investigated by using the synchrotron x-ray topographies, Cross-Nicole images and Cathodoluminescence (CL) mapping. The sample is epitaxial diamond film. It was deposited on HPHT Ib(100) substrates by microwave plasma CVD method. X-ray topographies were measured by using synchrotron hard x-ray at Photon Factory, BL-15C. For the defects depth profile discussion and quick measurement, synchrotron x-ray was used. The penetration depths was set by the changing the x-ray wavelength and incident angle to the sample surface. Most of observed dislocation direction is along <111>. These dislocations were also observed in Cross-Nicole images. A-Band CL mapping shows the dislocation where donor and accepter were recombinated. In our study, A-Band CL spots were able to see at same site of characteristic dot like defects in x-ray topography. Acknowledgment:The New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry of Japan financially supported this study. The x-ray topography experiment was performed under approval of the Photon Factory Advisory Committee (Proposal No. 2010G168). We thank Dr. T. Teraji(NIMS) for the measurement of CL mapping and valuable discussions.References:[1] “Leakage current analysis of diamond Schottky barrier diode," H. Umezawa, T. Saito, N. Tokuda, M. Ogura, S. G. Ri, H. Yoshikawa, S. Shikata, Appl. Phys. Lett. 90, 73506 (2007).[2] “Diamond low-leakage Schottky barrier diode,” H. Umezawa, K. Ikeda, N. Tatsumi, S. Shikata, Proceedings of ICSCRM 2007, We-P-81.[3] “Reduction of epitaxial defects in diamond for high power device,” N. Tatsumi, H. Umezawa, S. Shikata, Proceedings of ICSCRM 2007, Th-P-33.
9:00 PM - A5.2
Diamond Nanodot Arrays Fabricated by Room-temperature Nanoimprinting Using Diamond Molds.
Shuji Kiyohara 1 , Masaya Kumagai 1 , Hirofumi Takikawa 2 , Yuichi Kurashima 3 , Yoshio Taguchi 4 , Yoshinari Sugiyama 4 , Yukiko Omata 4
1 Advanced Faculty of Electric and Control System Engineering Course, Maizuru National College of Technology, Maizuru, Kyoto, Japan, 2 Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan, 3 Department of Mechanical System Engineering, University of Yamanashi, Kofu, Yamanashi, Japan, 4 , ELIONIX INC., Hachioji, Tokyo, Japan
Show AbstractThe nanopatterning technique of a diamond is essential to the fabrication of diamond-based micro/nano electronic, optical and mechanical devices, such as electron emitter, micro-lens and micro/nano-gear respectively. We have investigated the nanopatterning of chemical vapor deposited (CVD) diamond films in room-temperature nanoimprint lithography (RT-NIL), using a diamond mold. The diamond mold has a lifetime about 100 times longer than that of silicon dioxide (SiO_2) mold or that of silicon (Si) mold, both using a conventional NIL process. The reason for the longer lifetime is that diamond has many unique properties such as hardness, high thermal conductivity and low thermal expansion. The diamond mold has been fabricated by radio frequency (RF) oxygen plasma with Bi_4Ti_3O_12 octylate mask in the electron beam (EB) lithography technology that we developed. However, the maximum etching selectivity (diamond/ Bi_4Ti_3O_12 octylate films) of 3 is very small. To overcome this problem, we have proposed the use of polysiloxane [-R_2SiO-]_n, which has resistance to oxygen ion beams, as EB mask and RT-NIL resist materials in order to form an oxide film on surface and high viscosity.Compared to the conventional NIL process using PMMA [poly(methyl methacrylate)] which requires a thermal cycle, the RT-NIL process using polysiloxane has certain advantages, including short steps, high throughput and low cost. We have investigated the nanofabrication of three-dimensional (3D) diamond molds in Electron Cyclotron Resonance (ECR) oxygen ion beam etching technologies using polysiloxane as an EB mask and a RT-NIL resist material. The polysiloxane exhibited a negative-exposure characteristic and its sensitivity was 5.5×10^-5 C/cm^2. The maximum etching selectivity of polysiloxane film against diamond film was 4.7, which was obtained under the following ECR oxygen ion etching conditions : ion energy of 400 eV, ion incidence angle of 0 °, microwave power of 100 W, gas pressure of 1.4×10^-2 Pa. The diamond molds of cone and tetragonal pyramid dots were fabricated with polysiloxane mask in EB lithography technology using the RT- NIL process. The dots in minimum diameter and width are 500 nm. The pitch between the dots is 2 µm, and dots have a height of about 600 nm. It was found that the optimum imprinting conditions for the RT-NIL : time from spin-coating to imprinting of 1 min , pressure time of 5 min, imprinting pressure of 0.5 MPa. The imprinting depth obtained after the press under their conditions were 0.5 µm. The resulting diameter and width of each imprinted polysiloxane pattern was in good agreement with that of the 3D-diamond mold. We carried out the RT-NIL process for the fabrication of diamond nanodot arrays, using the 3D-diamond molds that we developed. The resulting 3D-diamond patterns of concave dot arrays with 500 nm diameter after ECR oxygen ion beam etching were fabricated.
9:00 PM - A5.20
Granular Nature of the Transport Properties in Superconducting Boron-doped CVD Diamond.
Gufei Zhang 1 , Stoffel Janssens 2 , Johan Vanacken 1 , Joris Van de Vondel 1 , Bram Willems 3 , Wim Decelle 1 , Joachim Fritzsche 1 , Isabel Guillamon 4 , Hermann Suderow 4 , Sebastian Vieira 4 , Ken Haenen 2 5 , Patrick Wagner 2 5 , Victor Moshchalkov 1
1 Katholieke Universiteit Leuven, INPAC – Insititute for Nanoscale Physics and Chemistry, Leuven Belgium, 2 Hasselt University, Institute for Materials Research, Diepenbeek Belgium, 3 Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Fisicas, Lima Peru, 4 Universidad Autonoma de Madrid, Departamento de Fisica de la Materia Condensadacas, Madrid Spain, 5 IMEC vzw, Division IMOMEC, Diepenbeek Belgium
Show AbstractWhen charge carriers are introduced in diamond, e.g. by chemical doping with Boron (B), C(1-x)B(x) exhibits an insulator-to-metal transition at a critical concentration pMott ~ 2 X 10+20 cm-3. Under even higher boron doping, diamond eventually becomes superconducting. This allows us to study the superconductor-insulator transition in boron-doped nanocrystalline CVD diamond thin films. A perpendicular magnetic field up to 5 T is applied to suppress the superconductivity and to study the magnetoresistivity in a broad temperature range. The transport measurements show pronounced granular effects, i.e. a broad superconducting transition: an extraordinarily high onset temperature versus a relatively low offset temperature, a negative thermoresistivity, and finally a negative magnetoresistivity. These observations are ascribed to both the extrinsic and the intrinsic granularities. The extrinsic granularity is the effect of the growth method which needs to start from a seeding of the substrate with nanocrystalline diamond, which acts as nucleation centers for further MPCVD growth of the film. By using STS/STM techniques, we also observed intrinsic granularity, meaning that within physical grains, there is a strong modulation of the superconducting order parameter. The Cooper pair and/or quasiparticle tunnelling in the ex/intrinsic grains are responsible for the transport behaviours.
9:00 PM - A5.21
Characterization of Diamond-like Carbon Thin Films Grown by Radio-frequency Assisted Pulsed Laser Deposition.
Maria Dinescu 1 , Mihaela Filipescu 1 , Marius Hutanu 2 , Nicu Doinel Scarisoreanu 1 , Ruxandra Birjega 1
1 , NILPRP, Bucharest Romania, 2 , North University Baia Mare, Baia Mare Romania
Show AbstractProperties such as hardness, mechanical resistance, and slickness make from diamond-like carbon (DLC) an ideal optical and wear-resistant coating. Thin films of DLC were obtained by laser ablation. A graphite target was irradiated in vacuum with lasers working at 193 nm and 266 nm respectively. A radio-frequency beam generated by a discharge in an external connected chamber was directed toward the substrate during the ablation process. Silicon, stainless steel and quartz were used as substrates, heated from room temperature (RT) to 473 K. Laser fluence was varied from 3 to 10 J/cm2. The morphological, structural and optical properties of the DLC layers were determined using techniques as Atomic Force Microscopy, X-ray diffraction, Secondary Ion Mass Spectroscopy, and optical absorption measurements. Smooth, textured thin films with performant optical characteristics were obtained for a narrow window of experimental conditions.
9:00 PM - A5.22
Synthetic Single Crystal Diamond Dosimeters for Application in Advanced Radiation Therapy Techniques.
Isabella Ciancaglioni 1 , Rita Consorti 2 , Francesco De Notaristefani 3 , Claudio Manfredotti 4 , Marco Marinelli 1 , Enrico Milani 1 , Assunta Petrucci 2 , Giuseppe Prestopino 1 , Claudio Verona 1 , Gianluca Verona Rinati 1
1 , INFN-Università di Roma ‘‘Tor Vergata’’, Rome Italy, 2 , Ospedale San Filippo Neri, Rome Italy, 3 , INFN-Università di Roma TRE, Rome Italy, 4 , INFN-Università di Torino, Turin Italy
Show AbstractDiamond physical properties, such as tissue-equivalence of the radiation absorption and high sensitivity per unit volume, make it an ideal candidate as active material for dosimetry in advanced radiation therapy techniques where very collimated beams are used. In this work, synthetic CVD single crystal diamonds (SSCD) in a p-type/intrinsic/metal structure were tested as dosimeters for narrow beam radiotherapy and for Intensity Modulated Radiation Therapy (IMRT) applications. The devices have been analyzed by using 6 and 10 MV bremsstrahlung x ray beams as well as electron in the range 6-18 MeV from a CLINAC DHX Varian accelerator. All measurements have been performed in a water phantom and commercial ionization chambers were used for calibration and comparison. No external bias voltage was applied to the diamond dosimeter during measurements. A fast response with no evidence of persistent photocurrent or memory effect was observed. No pre-irradiation procedure was found to be necessary in order to achieve a stability of the response within ± 0.5% and an excellent linearity of the dosimeter output was measured, showing a Fowler correction factor Δ = 1.0006 ± 0.0002. A detailed analysis of the dosimetric properties has been performed by means of percentage depth dose (PDD) curves, lateral beam profiles and output factors in the field sizes range from 0.6×0.6 cm2 up to 10×10 cm2. The results were found to be in a good agreement with the ones obtained with the reference ionization chamber. The temperature and angular dependence of the detector response have been also measured.One of such CVD single crystal diamond dosimeters has been successfully tested as a dosimeter in a prostate cancer IMRT treatment. The obtained results clearly indicate that CVD synthetic single crystal diamond based detectors can successfully be used in advanced radiotherapy dosimetry, possibly overcoming the limitations preventing the widespread diffusion of diamond devices in this field.
9:00 PM - A5.23
Parameters Affecting the Fluorescence of Nanodiamond Particles: Experiment and Quantum Chemical Calculations.
Irena Kratochvilova 1 , Alexander Kovalenko 1 , Vladimira Rezacova 1 4 , Frantisek Fendrych 1 , Stanislav Zalis 2 , Miroslav Ledvina 3 , Petr Cigler 3 , Milos Nesladek 5
1 , Institute of Physics, Prague 8 Czechia, 4 , Czech Technical University, Faculty of Biomedical Engineering, Kladno Czechia, 2 , J. Heyrovský Institute of Physical Chemistry, Prague 8 Czechia, 3 , Gilead Sciences and IOCB Research Center, Institute of Organic Chemistry and Biochemistry, Prague 6 Czechia, 5 , IMOMEC division, IMEC, Institute for Materials Research, University Hasselt, Diepenbeek Belgium
Show AbstractNanodiamond (ND) is a novel promising material for in-vitro and in-vivo imaging in living cells. ND offers novel advantages for the drug delivery development. Among advantages of ND belong the ability to penetrate into the cells without evoking a toxic cell response, their biocompatibility and stable luminescence originating from its colour centres.The dominant impurity in natural and synthetic diamonds is nitrogen. Aggregations of nitrogen admixtures with a vacancy creates thermally stable structures possessing high quantum efficiency [1]. Nitrogen-vacancy (NV) colour centres are either neutral (NV0) or negatively charged (NV-). Both of these centres are photostable and can be detected at the individual level which allows application of ND for functional intracellular imaging on the molecular level based on tagging specific molecular sites.In this work we studied the impact of different chemical termination of ND particles on the ND particles photoluminescence (PL). Recently, we have demonstrated the influence of atomic functional termination on changes in the occupation of NV- and NV0 states, with NV- quenching upon H- termination. To get qualitatively better understanding of the complicated and specific process of ND PL we used density functional theory (DFT) and modelled processes and states influencing PL of variously terminated ND particles. We modelled clusters containing from 35 to 120 atoms of carbon containing NV centers with different charge states (NV- & NV0) and with OH, H, NH2, carbonyl, carboxyl and hydroxyl groups terminations. Systems under study were modelled by DFT based calculations using Gaussian 09 and Turbomole-5.10. program packages. Unpaired electrons in triplet ground state of NV- centers in H-terminated clusters were found to be delocalized mainly on carbon and hydrogen atoms around the vacancy and the electron densities of nitrogen and other carbon atoms are only weakly changed. In case of H termination the NV- center charge is trapped in surface area and H atoms contribute to the highest occupied states. The whole system thus makes specific state with different conditions for luminescence. In the case of oxygen substituted clusters the contributing 2p O orbitals influence calculated transition energies and unpaired electrons in triplet ground state of NV- were found to be localized on nitrogen and carbon atoms - O atoms didn’t contribute to the highest occupied states preserving conditions for luminescence of surface non-affected NV- center in diamond particles.[1] K. Iakoubovskii, G.J. Adriaenssens, M. Nesladek, J. Phys. C, 12, 189-199, (2000)
9:00 PM - A5.24
The Experimental Performance of Microwave Plasma-assisted Reactors at High Pressures and High Power Densities.
Jes Asmussen 1 2 , Jing Lu 1 , Gu Yajun 1 , Timothy Grotjohn 1 2 , Donnie Reinhard 1 2 , Thomas Schuelke 2 , Kagan Yaran 2
1 Electrical and Computer Eng., Michigan State University, East Lansing, Michigan, United States, 2 , Fraunhofer USA, Center for Coatings and Laser Applications, East Lansing, Michigan, United States
Show AbstractIt is now widely understood that CVD synthesized diamond quality and growth rates can be improved by using high power density microwave discharges operating at pressures above 180 Torr [1]. Thus we have developed microwave plasma reactor designs and associated process methods that are both robust and are optimized for high pressure and high power density operation and thereby take advantage of the improved deposition chemistry and physics that exist in the high pressure regime. Here we will present the performance of two 2-5 KW, 2.45 GHz microwave plasma assisted CVD reactor designs that have been specifically designed and optimized for operation in the 200-320 Torr pressure regime. The reactor designs incorporate adaptable features that allow discharge matching and also the control of the position, size and shape of the very hot, spatially non-uniform, buoyant discharge that occurs at the 200-320 Torr pressure regime. Thus numerical solutions of the internal electromagnetic field patterns inside the reactor cavity versus a number of reactor design variables such as reactor size, substrate area and position, reactor matching, etc., are presented and then these numerical results are used to provide insight and explanations for the understanding of the experimental reactor performance. The numerical results are also used to help explain how an optimized diamond synthesis process can be obtained at high pressures and high power densities.The experimentally measured absorbed power density versus pressure increases from 150W/cm3 to over 600W/cm3 as pressure increases from 200-320 Torr and it can be controlled at each pressure by reactor tuning. The nonlinear reactor experimental performance, i.e. “operating road map” relating pressure, input power and substrate temperature, is analyzed for each rector and is then compared to similar road maps for lower pressure operation. The implication of reactor roadmap differences on process control is discussed. The two reactors are experimentally evaluated and compared by synthesizing single crystal diamond (SCD) using H2/CH4 input gas chemistries over the 200-320 Torr regime. SCD growth rates versus pressure, input gas chemistry (with and without N2 addition), and substrate temperatures are presented and output SCD quality is evaluated by IR to UV transmission measurements and SIMS analysis. Growth rates up to and over 100 microns/hr are obtained and optical quality diamond synthesis was achieved. References:[1] Silva F, Hassouni K, Bonnin X, and Gicquel, J. Phys.: Condens. Matter 21, 364202 (2009).
9:00 PM - A5.25
WITHDRAWN 12/21/10 Nano-diamond Particles for Neurotransmitter Biomolecules Detection.
Humberto Gomez 1 2 3 , Subbiah Alwarappan 1 2 , Ashok Kumar 1 2
1 Department of Mechanical Engineering, University of South Florida, Tampa, Florida, United States, 2 Nanotechnology Research & Education Center, University of South Florida, Tampa, Florida, United States, 3 Departamento de Ingenieria Mecanica, Universidad del Norte, Barranquilla Colombia
Show AbstractHerein we report, the suitability of nano-diamond particles for the detection of several important biomolecules such as ascorbic acid, dopamine and serotonin. The fore-told biomolecules are otherwise known as neurotransmitters and they play a key role in the neurotransmission event. The depletion or excess secretion of these neurotransmitters may cause several neurological disorders and as a result continuous monitoring of these neurotransmitters becomes vital. Furthermore, during the real time analysis, it is a very common phenomenon that the proteins, lipids and peptides present in the living cell adsorb to the electrode surface and it leads to electrode fouling. Electrode fouling is one of the serious problems often encountered during real time analysis and it can decrease the observed signal by 50%. In order to overcome or minimize the electrode fouling, there has been continuous efforts put forth by the researchers to come up with novel materials. As a continuing effort, in this work we employ nanodiamond particles that contains very less surface functionalities on its edge planes than its all other carbon counterparts. Initially, the purified nano-diamond particles were examined using a variety of surface characterizing techniques such as SEM, TEM, FT-IR, Raman and XRD. Following this, the purified nano-diamond particles were dissolved in a solvent and immobilized on to the gold electrode surface. The electrodes were then allowed to dry at room temperature. Following this, the electrodes were then employed for the electrochemical detection of the foretold biomolecules. Furthermore, the sensitivity and the stability of the nano-diamond particles were evaluated electrochemically.
9:00 PM - A5.26
Nanodiamonds for UV Detection.
Mose Bevilacqua 1 , Aysha Chaudhary 1 , Joseph Welch 1 , Richard Jackman 1
1 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractDiamond has been recognised as an near-to-ideal candidate for deep UV, solar blind, detection applications for many years. Indeed, our own research team has shown that both polycrystalline diamond and CVD grown single crystal diamond can, given suitable processing, perform such an operation with extremely high sensitivity and wavelength discrimination (Appl. Phys. Lett. 67, 2117 (1995); Appl. Phys. Lett. 95, 243501 (2009)). In both cases the surface area that can be covered by a potential device is limited by size of the growth plasma, for polycrystalline material, and of the substrate size for the single crystal case. In contrast, detonation-derived nanodiamonds (NDs, ~5nm)) can be coated on large area 3D substrates at room temperature using simple sonication methods. To date the optical properties of NDs have been dominated by non-diamond surface carbon and other absorbing functional groups. In this paper we describe methods for preparing ND coated surfaces that display excellent UV sensing properties, due to the absence of the otherwise problamatic surface groups. The potential for extremely high area UV detection systems will be discussed, and their use in future energy harvest systems considered.
9:00 PM - A5.28
Temporary Anchorage Devices (TADs) Coated with Nanocrystalline Diamond Films Using Low Temperature PE Linear Antennas MW CVD System.
Jana Fendrychova 1 , Vit Kopelent 2 , Tatjana Dostalova 1 , Karel Smetana 3 , Pavel Fendrych 4 , Jan Vlcek 5 , Andrew Taylor 5
1 Orthodontical Department, Second Faculty of Medicine, Charles University, Prague Czechia, 2 , 3M UNITEK CZ Ltd, Prague Czechia, 3 Department of Anatomy, First Faculty of Medicine, Charles University, Prague Czechia, 4 Faculty of Biomedical Engineering, Czech Technical University, Prague Czechia, 5 Institute of Physics, Academy Sciences CR, Prague Czechia
Show AbstractIn contemporary medicine, the explosive development of biomedical technologies and novel materials is recorded. Dentistry and its special disciplines are not excepted. In our research, we focus our attention on the dental implants. It is made of commercially pure titanium (Ti) or titanium alloy. Dental implants are used at most in two disciplines: prosthodontiscs and orthodontics. Its role in these lines differs. In prosthodontics, dental implants replace missing teeth and therefore a long term stability and strong osseointegrity is demanded. In orthodontics, dental implants play the role as the skeletal anchorage devices. Temporary Anchorage Device (TAD) is a device that is temporarily fixed to bone for the purpose of enhancing orthodontic anchorage. It allows for a fixed anchorage point that can be used to move teeth individually or en masse. Its period of use is limited, in average for six months (orthodontical treatment in general takes two years in average). For this type of implants, on the contrary, it is demanded, that the strength of osseointegrity would not be as high as in prosthodontical type of implants. The reason is, above all, an easy removal of it out of the bone, when the treatment goal is achieved. Unfortunately, it often happens, that the implant grows into the alveolar bone. 3M UNITEK Company handled the problem of overgrowing of TADs into the alveolar bone by a special mechanical configuration of the thread. The IMTEC™ ORTHO Implant has a modified buttress thread form: 1.8 mm diameter designed for strength and a 45 degree lead-in angle and 90 degree trailing angle, this thread form assists in insertion and retention of the implant. Our research is focused on improvement of TADs conditions in aspect of prevention of its overgrowing into the alveolar bone without loose of its biocompatibility and mechanical thread benefites. We have been solving this problems by coating of the IMTEC™ ORTHO Implant by pure or boron doped nanocrystalline diamond (NCD) films using a unique pulsed plasma enhanced linear antennas microwave CVD (PELAMWCVD) system which was designed and constructed in the Institute of Physics ASCR Prague in cooperation with Leybold Optics Dresden GmbH. This unique apparatus enables to cover the IMTEC™ ORTHO Implant with thin (200-400nm), smooth (Rms~10nm), adhesive and fully biocompatible NCD film at condition of low temperature (<350C). It prevents any structural or phase degradations of special titanium alloy implant. In this paper we present technological details, physical properties, biological and medical testing of IMTEC™ ORTHO Implants coated with NCD films by low temperature PELAMWCVD system.
9:00 PM - A5.29
Numerical Simulation of X-ray Section Topography Images of Defects in CVD Diamond.
Mengjia Gaowei 1 , Balaji Raghothamachar 1 , Erik Muller 1 , John Smedley 2 , Michael Dudley 1 , Qiong Wu 3
1 Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York, United States, 2 Instrumentation Division, Brookhaven National Laboratory, Upton, New York, United States, 3 Collider-Accelerator Division, Brookhaven National Laboratory, Upton, New York, United States
Show AbstractHigh purity, single crystal diamond wafers grown by CVD on HPHT substrates are candidates for high flux radiation detectors. A uniform response is clearly a requisite for such applications. While dislocations are the dominant defect in such diamond wafers, correlation of X-ray topographs with photodiode responsivity maps reveals that photoconductive gain is observed at locations where X-ray topographs reveal groups of threading dislocations originating from a secondary phase or inclusion. To understand the nature of this defect configuration, a series of section topographs have been recorded across the location of the defect and compared with simulations of expected defect configurations. Simulations use the DEFW program developed by Y. Epelboin. Single dislocations are easily identified by comparing the simulated image based on the strain field of known Burgers vector and orientation of the dislocation. However, the defect configuration at the active region is more complex as they are composed of multiple dislocations and an inclusion. By carefully recording section topographs of the defect configuration, we have attempted to capture the image of the inclusion (i.e. strain field around an inclusion) in isolation and comparing it with numerical simulations of expected strain fields around an inclusion. Through these comparisons, we expect to verify that the presence of an inclusion at the point of origin of the threading dislocations. Further, these comparisons will provide information on the size, orientation and depth of these defects. Results of these studies will be presented and discussed.
9:00 PM - A5.30
Selective Seeding and Growth of Ultrathin Ultrananocrystalline Diamond Films by Using Water-based Solution Containing Nanodiamond.
Anirudha Sumant 1 , Xinpeng Wang 1 2 , Olga Shenderova 3
1 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 2 , University of Puerto Rico, San Juan United States, 3 , International Technology Corporation, Raleigh, North Carolina, United States
Show AbstractRecently, there is a great interest in the synthesis and patterning of ultrathin (100 nm and below) nanocrystalline diamond films, for various applications in nanoelectronics, micro/nanoelectromechanical systems (M/NEMS) and as a conformal coating for electrodes in bio-medical applications. Use of nanodiamond particles either produced by detonation (DND) or by mechanical grinding of HPHT diamond has been shown to be very useful in seeding the substrate surface to produce thin diamond films with thickness down to 70 nm or less. It has been observed that in order to produce a continuous, pinhole-free UNCD thin film, an initial nucleation density in excess of 1011 cm-2 is required with average particle size in the range of 20 to 30 nm. The most common method used for the seeding is ultrasonic agitation in an alcohol solution. Water-based solution containing nanodiamond is more attractive since it eliminates waste containing alcohol and allows more flexibility for patterning with photoresist since it does not attack photoresist. In the case of water-based solution, however, the sample surface often needs to be treated in an acid solution to create a hydrophilic surface to achieve uniform wetting of the surface to get the best results. We present a method involving the use of water-based solution with nanodiamond (agglomeration size 5, 10 or 15 nm), where no chemical activation of the wafer surface is required. We show that a very thin (5-10 nm) layer of tungsten not only helps to reduce incubation time but also helps to spread nanodiamond particles uniformly due to the nano-scale roughness of the film resulting in partial embedding of DND particles in to the tungsten film. We have achieved pinhole-free UNCD thin films on 150-mm and 100-mm diameter silicon wafers with a film thickness less than 50 nm and on high-aspect-ratio structures such as AFM tips with film thickness down to 30 nm. Furthermore, we have developed a single step selective seeding process by using either positive or negative photoresist and demonstrate selective seeding and growth of UNCD with features size in the range of sub-microns. Since this method does not involve mixing nanodiamond with photoresist and reactive ion etching (RIE) process to remove unwanted seeds, it is very simple process to fabricate various diamond MEMS structures. We present detailed characterization of the substrate surface by using SEM, AFM, and XPS techniques and discuss the critical role played by the DND particles surface charge (zeta potential) and their interaction with the substrate surface.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
9:00 PM - A5.32
Focused Ion Beam Milling of Crystalline Diamonds.
Rustin Golnabi 1 , Won Lee 1 , Deok-Yang Kim 1 , Glen Kowach 2
1 Chemistry/Nanotechnology, Bergen County Academies, Hackensack, New Jersey, United States, 2 Chemistry, The City College of New York, New York, New York, United States
Show AbstractRecently, a wide range of new applications of diamond materials such as spintronics, field emission and bio-sensing have been proposed. These applications often require the precise pattering of diamonds, which is not trivial because diamonds are hardest materials known in the nature. Among various patterning techniques, a focused ion beam milling method has been proven to provide flexibility as well as high resolution in the pattern design. In this study, a focused beam of 30 keV Ga+ ions was utilized to create sub-micrometer size patterns out of crystalline diamonds. The sputtering rate, re-deposition, and surface roughening of diamond structure have been closely monitored with various milling parameters during the milling process. Our initial work revealed the low sputtering yield of 0.02 μm3/nC, high Ga content re-deposition and the formation of sub-micron scale terracing on the sidewall of patterned diamonds. Several strategies to improve the precision of diamond patterning will be discussed.
9:00 PM - A5.33
Composition, Bonding state, and Electrical Properties of Carbon Nitride Films Formed by Electrochemical Deposition Technique.
Hideo Kiyota 1 , Mikiteru Higashi 2 , Tateki Kurosu 3 , Masafumi Chiba 4
1 , Tokai University, Kumamoto Japan, 2 , Tokai university, Kumamoto Japan, 3 , Tokai university, Hiratsuka Japan, 4 , Tokai university, Numazu Japan
Show AbstractCarbon nitride (CNx) is a promising low-k material for multilevel interconnection of ULSI technology because of the useful properties such as extreme hardness, high resistivity and low dielectric constant [1]. Deposition of CNx film has been performed by conventional vapor-deposition techniques such as chemical vapor deposition, reactive sputtering, and pulse laser deposition [2]. On the other hand, the liquid-phase deposition of CNx film has been attempted as an alternative deposition technique by electrolysis of organic liquid containing nitrogen [3]. In this work, we have studied composition, bonding state, and electrical properties of CNx films grown by electrochemical deposition techniques. The CNx films are deposited by applying a DC bias voltage to Si substrates immersed in liquid acrylonitrile (CH2CHCN). The apparatus used for deposition consists of a glass vessel, two electrodes, and a DC power source. Si (100) substrates with the dimension of 20 × 40 mm are mounted on the both of two electrodes. Typical deposition parameters are a bias voltage of 3 kV, a current density of 1 mA/cm2, a liquid temperature of 70°C, and a deposition period of 1 h. Continuous and uniform films are deposited by the application of both negative and positive bias voltages. X-ray photoelectron spectra (XPS) demonstrate that C and N are major components of the grown films. Considerable amounts of oxygen and sodium impurities are detected in samples deposited under negative bias. In addition, the analysis of C 1s and N 1s spectra reveals that the major bonding states of the grown films are attributed to a mixture of C≡N and hydrogenated C=N bonds. To evaluate electrical properties of CNx films, metal-insulator-semiconductor (MIS) capacitors were fabricated by evaporation of Al electrodes onto the CNx surface. Resistivity of the grown film is determined to be higher than 1010 Ω cm at room temperature (300 K). Clockwise hysteresis was found in capacitance-voltage (C-V) curve of the MIS capacitor using the CNx films deposited under negative bias, indicating that the impurity incorporation and defect affect the electrical properties of the CNx films. On the other hand, typical accumulation and depletion behaviors are shown in the C-V curves of the MIS capacitor using the CNx films deposited under positive bias. Dielectric constants of the CNx layers are determined from the accumulation capacitance of the C-V curves, which show the dependence on the deposition parameters such polarity and duration of the bias application during the film growth.[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.
9:00 PM - A5.4
An Ab-initio Study of Li Adsorption onto the Diamond (100) Surface.
Kane O'Donnell 1 2 , Tomas Martin 2 , Neil Fox 3 , David Cherns 3
1 Centre for Nanoscience and Quantum Information, University of Bristol, Bristol United Kingdom, 2 School of Chemistry, University of Bristol, Bristol, Bristol, United Kingdom, 3 Physics Department, University of Bristol, Bristol, Bristol, United Kingdom
Show AbstractDiamond vacuum microelectronic devices such as photocathodes, field emitters and thermionic emitters typically rely on the existence of a negative electron affinity (NEA) at the surface, where the conduction band minimum is higher in energy than the vacuum level1. A negative electron affinity can be quite easily induced on diamond through the action of surface dipoles generated by certain coatings or terminations of the surface. Caesium oxide2, hydrogen1 and thin metal films3 have all been demonstrated to induce a NEA on the diamond (100) surface. CsO films can induce a large NEA on diamond but are not stable at thermionic temperatures, with hydrogen termination being the surface of choice when thermal stability is required. We have investigated Li films on clean and oxygenated diamond as a more strongly-bonded alternative to the CsO system with density functional theory (DFT) using the CASTEP4 program. We find that a single monolayer of lithium adsorbed onto the C(100)-(1x1):O surface shows a very large workfunction shift of -4.52 eV relative to the clean surface, similar to that seen experimentally for caesium-oxide coatings on diamond. However, in contrast to the caesium case, the lithium monolayer is very strongly bound and should be stable at high temperatures. We propose that such a surface is a candidate for practical diamond electron emission devices.
1F.A.M. Koeck, J.M. Garguilo and R.J. Nemanich, Diamond and Related Materials 13(11-12), 2052 (2004)
2J. Foord, K. Loh, R. Egdell, and R. Jackman, Diamond and Related Materials 6, 874 (1997)
3P.K. Baumann and R.J. Nemanich, Journal of Applied Physics, 83(4), 2072 (1998)
4S.J. Clark, M.D. Segall, C.J. Pickard, P.J. Hasnip, M.J. Probert, K. Refson, M.C. Payne, Zeitschrift für Kristallographie 220(5-6), 567-570 (2005)
9:00 PM - A5.5
Phase Transition and Self-assembly of Lower Diamondoids and Derivatives.
Yong Xue 1 , Ali Mansoori 2
1 BioEngineering, University of Illinois at Chicago, Chicago, Illinois, United States, 2 Physics, University of Illinois at Chicago, Chicago, Illinois, United States
Show AbstractDiamondoids and their derivatives have found major applications as templates and as molecular building blocks in nanotechnology. Applying ab initio and molecular dynamics methods, we have been calculating and predicting the essential phase transition and self-assembly of two lower diamondoids (adamantane and diamantane) and three of their important derivatives (amantadine, memantine and rimantadine). We are also studying two organo-metallic molecules that are built by substituting one hydrogen ion with one sodium ion in both adamantane and diamantane molecules. To study their self-assembly and phase transition behaviors, we built seven different MD simulation systems, and each system with 125 molecules. We obtained self-assembly structures and simulation trajectories for the seven molecules. Radial distribution functions and structure factors studies showed clear phase transitions for the seven molecules. Higher aggregation temperatures were observed for diamondoid derivatives and hydrogen bonding also appeared in three adamantane derivatives. Our results indicate: 1.The nature of self-assembly and phase transition in these molecules is a structure-dependent phenomenon. 2. Final self-assembly structures depend on the different bonding types present in the molecular structure of these various molecules. 3. The organo-metallic molecules still hold neat crystal structures. Although -Na ion increases the phase transition temperature, as those the -NH2 ion in group 2, in a large extent the structural features of diamondoids are retained in adamantane-Na and diamantane-Na. The reasons for the latter might be that: A. The -Na ion has less topology effect than does the -NH2 ion. B. There is no hydrogen-bonding in the structures of adamantane-Na and diamantane-Na, therefore they can aggregate to an ordered structures. This feature is very promising, since it allows us to build orderly-shaped NEMS and MEMS.
9:00 PM - A5.6
Fabrication of p-n Junction Diamond Diodes with N-type Arsenic-doped Diamond.
Makoto Kasu 1 , Michal Kubovic 1
1 , NTT Basic Research Laboratories, Atsugi Japan
Show AbstractDiamond possesses the highest breakdown field and thermal conductivity and exhibits high mobilities. Therefore diamond devices are expected to exhibit the best performance in high-frequency power operation among semiconductors. However, n-type impurity doping is still a critical issue for diamond. Sque et al. and Goss et al. estimated the ionization energy of specific elements in diamond in density functional calculations and predicted substitutional arsenic (As) donor at 0.4 eV below the conduction band minima [1, 2]. Using trimethyarsine (TMAs) as an As source, Frangieh et al. reported As doping in CVD diamond growth [3] and an As concentration in a range of 1017 cm-3 but did not report any electrical conduction. In this work, As-doped single-crystal diamond layers were homoepitaxially grown by microwave plasma chemical vapor deposition. Tertiarybutylarsine (t-C4H9AsH2, TBA) was used as an As source. TBAs is a less toxic metalorganic liquid and is decomposed at lower temperatures than arsine (AsH3). The N residual concentration in the layer was estimated to be less than the detection limit <1 ppb, 2x1014 cm-3. The n-type conduction of the As-doped layers was confirmed both in Hall measurements and from the current-voltage characteristics of the diodes. In the As-doped layers, electron concentration increased with As concentration in the layers. Thus, we confirmed that electrons are generated from As donors. From the temperature dependence of electron concentration, we deduced the ionization energy of As donors decreased from 1.6 to 0.8 eV with As concentration from 1x1017 to 9x1019 cm-3. Finally we grew n-type As-doped diamond on HPHT type-IIb B-doped p-type substrate and fabricated p-n junction diodes, which exhibited a rectification ratio of ~1000 at 10 V at room temperature. A part of this work was supported by the SCOPE “Diamond RF Power Amplifier Project” of the Ministry of Internal Affairs and Communications of Japan.[1] J. P. Goss, P. R. Briddon, R. Jones, and S. Sque, Diamond and Related Materials 13, 684 (2004). [2] S. J. Sque, R. Jones, J. P. Goss, and P. R. Briddon, Phys. Rev. Lett. 92, 017402 (2004). [3] G. Frangieh, M. –A. Pinault, J. Barjon, F. Jomard, and J. Chevallier, Phys. Stat. Sol. (a) 205, 2207 (2008).
9:00 PM - A5.7
Substrate Temperature Dependence of Carbon Nanocomposites Deposited by Hot Filament Chemical Vapor Deposition.
Michael Walock 1 , Rhys Miller 2 , Yujiao Zou 1 , Andrei Stanishevsky 1
1 Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama, United States, 2 Department of Physics, Grove City College, Grove City, Pennsylvania, United States
Show AbstractNanocomposites of carbon allotropes have proven to have unique physical and electronic properties. However, the typical deposition methods are not easily scalable for large scale manufacturing. One possible alternative is the hot filament chemical vapor deposition (CVD) technique. With this technique, we can deposit nanostructured films of different carbon allotropes. Specifically, we are targeting a composite of carbon nanotubes and nanodiamond. The deposition parameters of filament temperature, pressure, gas composition, and substrate temperature are being investigated in order to determine their effects on the nanocomposite films. In addition, several substrate surface pretreatments will be investigated. The resultant samples are characterized with atomic force microscopy, scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and Raman spectroscopy.
9:00 PM - A5.8
Polishing of Polycrystalline Diamond Films Using Microwave Plasma-assisted Etching.
Dzung Tran 1 , Timothy Grotjohn 1 2 , Donnie Reinhard 1 2 , Jes Asmussen 1 2
1 Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan, United States, 2 Center for Coatings and Laser Applications, Fraunhofer, East Lansing, Michigan, United States
Show AbstractPolycrystalline diamond films are promising for several applications for which a smooth surface is important, such as optical windows, X-ray masks, SAW filters and other electronic devices. Mechanical lapping and polishing techniques are fairly well established, however the diamond lapping removal rate is very low. Consequently there is interest in the development of more efficient smoothing methods. Examples include thermal-chemical polishing [1], laser polishing [2] and planarizing layers combined with oxygen ion-beam etching [3]. This paper describes development of methods to smooth polycrystalline diamond films using microwave plasma assisted etching combined with mechanical polishing and combined with sacrificial planarizing layers. A 2.45 GHz, microwave plasma-assisted etching reactor is utilized for high etch rate processes on diamond substrates as previously described [4]. The first surface smoothing method combines plasma etching with mechanical lapping/polishing. The whiskers, produced on the diamond surface after plasma etching due to the micro-masking effect are relatively easy to remove by the mechanical lapping/polishing. Using this method in which etching, followed by lapping/polishing was repeated several times, the surface roughness Ra was improved from 3802 nm to 53 nm. This method shortens the time required for smoothing, but still required both mechanical lapping and polishing. The second method combines plasma etching and planarizing layers such that the etch is designed to remove the planarizing layer and diamond at comparable rates. Planarizing layers have included photoresist, Si3N4, and SiO2 with the latter showing best results. A plasma-enhanced chemical vapor deposition (PECVD) layer of oxide is deposited to a thickness comparable to the RZ of the diamond surface. Then the oxide layer is polished and planarized using chemical-mechanical-polishing. This step is followed by plasma-assisted etching sufficiently long to remove the remaining oxide. The result is a significantly smoother diamond surface created without the need for a time consuming lapping step. Sequential applications of the procedure produce optically smooth surfaces. Important experimental parameters include etch-gas composition and mechanical polishing speed and down force. References[1] M. Yoshikawa, Diamond Optics III, SPIE, 1325, 210 (1990).[2] A.M. Ozkan, A.P. Malshe, W.D. Brown, Diamond and Relat. Mater., 6, 1789 (1997).[3] D. F. Grogan, T. Zhao, B.G. Bovard, and H. A. Macleod, Applied Optics, 31, 1483 (1992).[4] D. T. Tran, T. A. Grotjohn, D. K. Reinhard, J. Asmussen, Diamond and Relat. Mater., 17, 717 (2008).
9:00 PM - A5.9
Visible Light Photo Emission and Thermionic Emission from Nitrogen-doped Ultra-nanocrystalline Diamond.
Tianyin Sun 1 , Franz Koeck 1 , Chiyu Zhu 1 , Robert Nemanich 1
1 Department of Physics, Arizona State University, Tempe, Arizona, United States
Show AbstractCarbon based materials including diamond and carbon nanotube films have long been under investigation for their application as electron sources. While doped diamond films have been recently shown efficient thermionic emission, the low work function due to doping and negative electron affinity (NEA) effects suggests the possibility of photo-emission with visible light irradiation. We have prepared nitrogen-doped ultra-nanocrystalline diamond (UNCD) films on metallic substrate as a low-temperature photo electron and thermionic electron emitter. With the NEA caused by hydrogen termination, the UNCD emitters showed an effective work function as low as 1.3 - 1.7 eV revealed by ultraviolet photo-emission spectroscopy (UPS) measurements. Illuminating the N-doped diamond emitter with a 406nm diode laser resulted in significant electron emission at room temperature. At a temperature of ~ 500°C, the optical excitation resulted in considerable increase in emission current, and the electron energy spectra indicated comparable peaks due to thermionic emission and photo electron emission. The relative position of the photo electron peak to the thermionic electron peak shifted with temperature, indicating electron-electron scattering in the conduction band. In preliminary results with white LED and 532nm laser irradiation, small photo-emission signals were also observed from some of our N-doped diamond emitters. With these results the UNCD films appear to be candidates as efficient photo electron emitters for photo cathode applications. This research is supported through the Office of Naval Research.
Symposium Organizers
Philippe Bergonzo CEA-LIST
Commissariat Energie Atomique (CEA/Saclay)
James E. Butler (Retired from Naval Research Laboratory)
Christoph E. Nebel Fraunhofer Institut fuer Angewandte Festkoerperphysik
Andrew T. S. Wee National University of Singapore
Milos Nesladek Hasselt University & IMEC vzw
A6: Advanced Surface Characterisation of Diamond
Session Chairs
Tuesday AM, November 30, 2010
Room 306 (Hynes)
9:30 AM - **A6.1
Adsorption of Water Molecule on Bare and Deuterated Diamond Surface: High Resolution Electron Energy Loss Spectroscopy Studies.
Alon Hoffman 1
1 Chemistry, Technion, Haifa Israel
Show AbstractIn this work we study the interaction of water molecules with deuterated and bare polycrystalline diamond film surfaces upon exposure to water vapor by X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HR-EELS). To distinguish the molecular origin of hydrogen bonds (i.e. C-H, O-H, C-O-H, etc) formed on the diamond surface upon interaction with the water molecules, deuterated and hydrogenated gases were used in our experiments. Diamond films were deposited from a deuterated gas mixture to prepare C(di)-D surface terminations Water adsorption on bare diamond surface gives rise to the appearance of well defined and pronunced C-H and -O-H vibrational peaks and an intense O(1s) peak. Annealing to ~500-600 C of the water exposed bare diamond surface results in disappearance of the -O-H vibrational modes alongside with a pronounced reduction of the C-H vibrational modes, whilst only upon annealing to ~800 C the O(1s) peak decreased substantially in intensity. Water exposure onto the deuterated surface, on the other hand, does not result in the appearance of the –O-H vibrational peaks but only to an increase of the C-H vibrational mode along side with the appearance of a weak O(1) peak. Annealing of the water exposed deuterated diamond surface, results in a pronounced decrease and disappearance of the O (1s) XPS peak at a temperature of ~800 °C.
10:00 AM - A6.2
Real-time Monitoring of Diamond Surface Processing at High Temperature.
Andrew Evans 1 , Gruffudd Williams 1 , Owain Williams 1 , Simon Cooil 1 , David Langstaff 1
1 Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth United Kingdom
Show AbstractIn the application of diamond as an electronic material, high temperatures are used both in processing and in some cases during operation. This can induce changes in surface bonding and in the distribution and occupancy of electronic states. Few experimental techniques can probe both chemical and electronic changes and fewer still can be applied in-situ. One such tool is photoelectron spectroscopy where recent advances in parallel electron detection have enabled data acquisition time to be reduced sufficiently for it to become a real-time characterisation method. Temperature-dependent changes in single-crystal diamond (001) and (111) surfaces have been probed using such an approach by monitoring the intensity and energy of photoelectrons excited from core levels during programmed heating cycles. Significant changes in surface charge distribution and Fermi level position relative to the band edges are revealed at temperatures as low as 600K for (001) and (111) diamond surfaces terminated with O and H. These heated surfaces are electronically very different to the room temperature phases although they are structurally unchanged up to the reconstruction temperature of around 1200K. The C-terminated, reconstructed surface does not exhibit such strong temperature-induced changes in the electronic structure. These results are discussed in terms of meta-stable high-temperature surface phases and affects associated with the photoexcitation process.
10:15 AM - A6.3
Investigation of Li-O Dipoles on Single Crystal Diamond.
Tomas Martin 1 2 , Kane O'Donnell 2 , Neil Fox 1 2 , David Cherns 1
1 H.H. Wills Physics Laboratory, University of Bristol, Bristol United Kingdom, 2 School of Chemistry, University of Bristol, Bristol United Kingdom
Show AbstractDiamond’s mechanical hardness and thermal stability, as well as its wide band gap, make it an ideal candidate for vacuum microelectronics including field emission and thermionic emission devices. Hydrogen terminated diamond has been shown to induce a negative electron affinity (NEA) on the diamond surface, where the conduction band minimum is lower in energy than the vacuum level1. It has been suggested that NEA materials may mitigate the saturating space charge effect2. Recent work by our group has predicted a strong surface dipole on the (100) face of oxygen-terminated diamond when a single monolayer of lithium is present3, reducing the workfunction by -4.52eV relative to the clean surface. The surface contains two lithium and two oxygen atoms per reconstructed unit cell, and is predicted to behave similarly to the Cs-O dipole on diamond4, but with a binding energy of 4.7eV, far higher than that of Cs-O. The presence of such a surface coating is highly attractive for electron emission and promising low threshold thermionic and field emission has been observed using Li-O doped diamond nanopowders, with effective workfunctions around 1eV5. The work presented herein details experimental construction of such a Li-O dipole on single crystal diamond squares. The investigation studied monocrystalline CVD and HPHT diamond with (100) orientation, in addition to monocrystalline HPHT diamond in the (111) orientation. These samples were oxygen-terminated using ozone treatment, oxygen plasma or by washing in fuming nitric acid. The oxygen-terminated surfaces were then coated with lithium by evaporation or decomposition of lithium salts. X-ray photoemission spectroscopy (XPS) of the lithium 1s excitation showed a shift to 57eV, characteristic of an Li2O2 structure on the diamond surface. The resultant surfaces were characterised and compared using photoemission spectroscopy and scanning probe microscopy. This paper will detail the results of those studies in more detail and compare the experimental surface to the predicted behaviour.1 J van der Weide, Z Zhang, P K Baumann, M G Wensell, J Bernholc, R J Nemanich, Physical Review B 50 8 5803-5806 (1994)2 J R Smith, G L Bilbro, R J Nemanich, Physical Review B, 76 24 245327 (2007) 3 K M O’Donnell, T L Martin, N A Fox, D Cherns, Physical Review B, submitted4 Kian Ping Loh, X. N. Xie, S. W. Yang, J. S. Pan, P. Wu, Diamond and Related Materials, 11 7 1379-1384 (2002) 5 T L Martin, K M O’Donnell, G Fuge, N A Fox, D Cherns, Applied Physics Letters, in preparation
10:30 AM - A6.4
Direct Carboxylation on Single Crystal Diamond Surface (100) and (111).
Xianfen Wang 1 , Ruslinda A.Rahim 1 , Robert Edgington 2 , Yuichiro Ishiyama 1 , Yoko Ishii 1 , Hiroshi Kawarada 1
1 School of advanced science and engineering, Waseda University, Shinjuku, Tokyo, Japan, 2 Electronic and Electrical Engineering, UCL, London United Kingdom
Show AbstractIn the diversity of surface functionalizations, carboxyl terminations can serve as extremely useful binding sites for covalent immobilizing biomolecules, because the amide bonds are formed by carboxyl and amino groups. However, researchers usually choose complex chemicals containing carboxylic groups as linkers [1, 2], of which the length inevitably reduce the interaction between biomolecules and solid surface leading to the insufficient performance of biosensor, especially in transistor biosensor. Therefore, it is of high applicability to obtain carboxyl groups directly using abundant carbon atoms in diamond itself. In our lab, hydroxyl and carboxyl terminated polycrystalline diamond has been successfully achieved via wet chemical oxidization treatment, and the surface can serve as a suitable stage for single nucleotide polymorphisms (SNPs) detection with high sensitivity. [3, 4] Unfortunately it is still in faint understanding why polycrystalline diamond, composed of (111) and (100) crystal planes, can be successfully oxidized with carboxylic acid groups, and what is the difference between (111) and (100) surface after oxidation treatment. In this research direct carboxylation modification on (111) and (100) substrates are compared using quantitative X-ray photoelectron spectroscopy (XPS) analysis. Samples were subjected to a strong acid solution for oxidization, and then a boron doped layer was homoepitaxially deposited on one side of substrate to minimize charging effects in XPS measurement. High resolution XPS analysis reveals distinct oxygen-containing components have been successfully achieved with different coverages on (111) and (100) surface, with the following apparent differences in the surface functionalisations of (111) and (100) diamond: (1) a relatively high coverage of carboxylic groups has been obtained for (100) and (111) with a percentage of ~9% and ~5% respectively compared with previous report [5]; (2) at the same time, a higher percentage of hydroxyl groups have been formed on (100) diamond (~24%) in comparison to (111) diamond (~9%); (3) the simple wet chemical treatment effectively enhance the percentage of carboxylic acid groups on the diamond surface, and the crystal orientation has a critical effect on the surface coverage of distinct oxygen-containing groups. According to theoretical calculations [6, 7], different surface coverages of carbon-oxygen groups on (100) and (111) diamond are ascribed here to the surface rearrangement of carbon atoms imposed by oxidization process. [1] A. Hartl et al. Nature materials. 3, 736, 2004. [2] J. H. Yang, H. Kawarada et al. Langmuir 22, 11245, 2006.[3] S. Kuga, H. Kawarada et al. J. Am. Chem. Soc. 130, 13251, 2008.[4] Y. Ishii, H. Kawarada et al. 2009 MRS Fall meeting. [5] S. Ghodbane et al. Phys. Stat. Sol. (a) 203, 3147, 2006.[6] H. Tamura et al. Physical review B. 61, 11025, 2000.[7] K. P. Loh et al. J. Phys. Chem. B. 106, 5230, 2002
10:45 AM - A6.5
Synthesis of Transparent Mesoporous Diamond from Periodic Mesoporous Carbon CMK-8 at 1300°C and 21 GPa.
Li Zhang 2 , Paritosh Mohanty 1 , Neil Coombs 3 , Yingwei Fei 2 , Ho-Kwang Mao 2 , Kai Landskron 1
2 Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, United States, 1 Chemistry, Lehigh University, Bethlehem, Pennsylvania, United States, 3 Chemistry, University of Toronto, Toronto, Ontario, Canada
Show AbstractWe report about the synthesis of optically transparent, mesoporous, monolithic diamond from periodic mesoporous carbon CMK-8 at a pressure of 21 GPa. The phase transformation is complete already at a mild synthesis temperature of 1300 °C without the need of a catalyst. Surprisingly, the diamond is obtained as a mesoporous material despite the extreme pressure. XRD, SEM, TEM, SAED, HR-TEM, and Z-contrast experiments suggest that the mesoporous diamond is composed of interconnected diamond nanocrystals having diameters around 5-10 nm. The BET surface area was determined to be 33 m2g-1 according Kr sorption data. The mesostructure is diminished yet still detectable when the diamond is produced from CMK-8 at 1600 °C and 21 GPa. The temperature dependence of the porosity indicates that the mesoporous diamond exists metastable and withstands transformation into a dense form at a significant rate due to its high kinetic inertness at the mild synthesis temperature. The findings point toward ultra-hard porous materials with potential as mechanically highly stable membranes.
A7: Defects in Diamond and Quantum Applications
Session Chairs
Tuesday PM, November 30, 2010
Room 306 (Hynes)
11:30 AM - **A7.1
EPR of Fundamental Defects in Diamond.
Junichi Isoya 1
1 , University of Tsukuba, Tsukuba Japan
Show Abstract Since physical properties of bulk diamond crystals are affected strongly by point defects, identification of defects is important in developing stage of semiconductor applications. As demonstrated by the NV center, novel applications are potentially brought by point defects. In diamond, SiC, and silicon, EPR (electron paramagnetic resonance) has proved to be most successful technique in identifying defects. In these lattices, abundance of isotope(s) with zero nuclear spin is high. Therefore, EPR spectra of deep defects are benefitted by narrow linewidth (i.e. high sensitivity) and satellite lines arising from hyperfine (HF) interactions with 13C (I=1/2, 1.1%) and 29Si (I=1/2, 4.7%). These HF tensors do supply detailed structural information such as the spin density, the sp ratio and the direction of p-orbital. In diamond, 13C enrichment is sometimes crucial in observing the 13C satellite lines from the first shell (i.e. major atom(s) comprising a defect). In most of defects in diamond, the unpaired electron is strongly localized on the first shell. Thus, the HF lines from further shells such as next-nearest-neighbors in NV are not well-resolved from the primary lines. In these cases, 13C enrichment brings inhomogeneous broadening of the EPR lines due to unresolved HF interactions. We demonstrate that high resolution methods such as ESEEM (electron spin echo envelope modulation) and pulsed ENDOR (electron nuclear double resonance) do extract these weak HF interactions which are critically important in some novel applications. The spin density and sp ratio of atom(s) in the first shell (nearest-neighbors in the case of vacancy) of intrinsic defects are compared among diamond, SiC and silicon. The intrinsic defects in diamond are unique in having strong tendency of strong localization and large p-character of the first shell atoms.
12:00 PM - A7.2
Quantum Photonic Devices Based on Single Color Centers in Diamond Nanostructures.
Thomas Babinec 1 , Birgit Hausmann 1 , Jennifer Choy 1 , Sungkun Hong 2 , Mike Grinolds 2 , Patrick Maletinsky 2 , Amir Yacoby 2 , Marko Loncar 1
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Physics, Harvard University, Cambridge, Massachusetts, United States
Show AbstractThe development of materials processing techniques for robust, scalable, and room-temperature single photon sources is an important problem in quantum science and technology. Towards this end, we have recently demonstrated device arrays of a high-flux single photon source consisting of a Nitrogen-Vacancy (NV) center randomly embedded in a diamond nanowire antenna (Ref. 1-3). Future devices that utilize both the spin and photon qubits of the NV center as a resource for information processing will require the deterministic implantation of single NV centers in high purity (Nitrogen concentration ~ 1ppm) diamond nanophotonic devices. We describe our recent work developing such a implantation technique. Nitrogen atoms were implanted at 14keV into an electronic grade (N ~ 1ppm) bulk diamond crystal at a dosage of 1.25*1012 /cm2, giving a projected range of approximately 20nm below the surface. Annealing for two hours at 750 degrees Centigrade generates a shallow implant layer of NV centers. Electron-beam lithography and reactive ion etching generates ~100nm diameter nanoparticles of height ~200nm sitting on top the bulk diamond crystal. This mechanically isolates individual NV centers and minimizes background fluorescence. This is confirmed by photoluminescence measurements, which show the characteristic NV center spectrum. Moroever, photon autocorrelation of measurements of the device fluorescence show strong photon anti-bunching of g(2)(0) ~ 0.25, indicating non-classical light emission from a single NV center in the diamond nanoparticle. We will also discuss our recent efforts to combine this ion implantation technique with the diamond nanowire antenna architecture. References:1. B. Hausmann et. al., “Fabrication of Diamond Nanowires for Quantum Information Processing Applications”, Diamond and Related Materials, Volume 19, Issues 5-6, May-June 2010, Pages 621-629.2. T. Babinec et. al., “A Diamond Nanowire Single Photon Source”, Nature Nanotechnology, 5, 195 (2010).3. M. Loncar, T. Babinec, B. Hausmann, “Diamond Nanotechnology”, SPIE Newsroom (2010).
12:15 PM - A7.3
Group Theoretical Analysis of Nitrogen-vacancy Center's Energy Levels and Selection Rules.
Jeronimo Maze 1 2 , Adam Gali 3 , Emre Togan 2 , Yiwen Chu 2 , Alexei Trifonov 2 , Efthimios Kaxiras 2 4 , Mikhail Lukin 2
1 Physics, Pontificia Universidad Catolica, Santiago Chile, 2 Physics, Harvard University, Cambridge, Massachusetts, United States, 3 Atomic Physics, Budapest University of Technology and Economics, Budapest Hungary, 4 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
Show AbstractDefect in solids such as the nitrogen-vacancy center in diamond are promising candidates for high precision measurements, quantum information and quantum communication. A vast knowledge of their complicated dynamics is essential to effectively implement these applications. Here, we show that group theoretical analysis can be successfully used to unravel the properties of any point defect in solids. In particular, we work out in detail the energy levels and selection rules of the nitrogen-vacancy center and show how they can be implemented in applications such as spin-photon entanglement, an essential step towards quantum communication. Furthermore, we analyze the performance of these properties under perturbations that reduce the symmetry of the defect such as strain and electric field. We provide useful guidance on how to overcome these undesired perturbations and compare our model with recent experimental results.
12:30 PM - A7.4
Nanofabrication of Single Spins and Spin Arrays in Diamond.
David Toyli 1 , Christoph Weis 2 , Gregory Fuchs 1 , Thomas Schenkel 2 , David Awschalom 1
1 Center for Spintronics and Quantum Computation, University of California, Santa Barbara, Santa Barbara, California, United States, 2 Ion Beam Technology Group, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractNitrogen vacancy (NV) centers in diamond are a promising solid-state qubit for spin-based quantum information processing and high-precision metrology. High-fidelity, coherent spin manipulation of isolated NV centers has advanced such that achieving over 106 coherent manipulations appears feasible at room temperature. However, the production of multi-qubit NV center entanglement requires the development of techniques to accurately place single NV centers on 10 nm length scales. To address this challenge we have developed a method for nanofabricating single NV centers based on conventional electron beam lithography and ion implantation techniques [1]. By masking nitrogen implantation with apertures in electron beam lithography resist we have fabricated single NV centers with lateral placement accuracies on the order of 10 nm. This approach also offers high throughput: resist apertures are patterned at a rate of over 106 per hour. Secondary ion mass spectroscopy measurements facilitate depth profiling of the implanted nitrogen to provide three-dimensional characterization of the NV center spatial distribution. Finally, pulsed electron spin resonance measurements of single implanted NV centers suggest a pathway for optimizing single-spin coherence to apply this nanofabrication technique toward the production of large-scale NV center arrays for spin-based quantum computing architectures.[1] D. M. Toyli et al., submitted (2010).
12:45 PM - A7.5
On the Mechanism of Charge Transfer between Neutral and Negatively Charged Nitrogen-vacancy Color Centers in Diamond.
Vladimira Rezacova 1 2 , Milos Nesladek 3 , Petr Cigler 4 , Miroslav Ledvina 4 , Jan Kucka 5 , Jan Stursa 5 , Jan Ralis 5 , Jiri Vacik 5 , Peter Mojzes 6 , Andrew Taylor 1 , Irena Kratochvilova 1 , Frantisek Fendrych 1
1 , Academy of Sciences of the Czech Republic, Institute of Physics, v.v.i, Prague Czechia, 2 , Czech Technical University, Faculty of Biomedical Engineering, Kladno Czechia, 3 , IMOMEC division, IMEC, Institute for Materials Research, University Hasselt, Diepenbeek Belgium, 4 , Gilead Science and IOCB Research Center, Institute of Organic Chemistry and Biochemistry, v.v.i., Academy of Sciences of the Czech Republic, Prague Czechia, 5 , Institute of Nuclear Physics, Academy of Sciences of the Czech Republic, v.v.i, Rez near Prague Czechia, 6 , Charles University in Prague, Faculty of Mathematics and Physics, Prague Czechia
Show AbstractThe presented work aims for the development of optically-traceable intracellular nanodiamond sensors, where photoluminescence can be changed by biomolecular attachment/delivery event. Nanodiamond (ND) [1] brings advantages over classical fluorescent markers used for in vivo and in vitro imaging in living cells by offering a cellular delivery combined with strong and stable photoluminescence (PL) originating at nitrogen-vacancy (NV) or other lattice point defects. In our recent works, we have demonstrated the influence of atomic functional termination on changes in the occupation of NV- and NV0 states, with NV- quenching upon H- termination. In the present work we have studied interaction of ND with variously charged macromolecules. Explicitly we compare covalent (H, OH, COOH, etc.) and noncovalent (positively and negatively charged polymers) charge interactions with the surface shallow-laying NV centres. NV photoluminescent (PL) centres in high-pressure high-temperature ND of 30 nm size were produced by irradiation by 10.6 MeV protons. The HPHT ND was compared with single crystal CVD diamond (SC CVD) plates in which the individual NV centres were produced by shallow N-implantation. ND and SC CVD were annealed, chemically oxidized and further on hydrogenated in H-plasma. Raman and PL (excited by 514 nm and 532 nm) spectra were recorded from untreated, treated (nitrogen implanted and annealed) and from oxidised / hydrogenated samples at room temperature. Spectra were also taken from colloidal dispersions (i.e. in liquid) of ND with various negatively and positively charged polymers, using microfluidic setup. Oxidized samples and colloid solution of ND with positively charged polymers exhibited strong NV PL, while NV PL of hydrogenated ND and for ND dispersed with negatively charged polymers was significantly comparatively lower. The results are supported by theoretical modelling of density of state distribution for various surface interactions.[1] Krueger A., Chem. Eur. J., 14, 1382-1390, (2008)
A8: Diamond Bio-Surfaces and Implants
Session Chairs
Tuesday PM, November 30, 2010
Room 306 (Hynes)
2:30 PM - **A8.1
Nanodiamond Monolayer Coating Promotes Attachment and Growth of Electrically Functional Neurons.
Ralf Schoepfer 1 , Agnes Thalhammer 1 , Robert Edgington 2 , Lorenzo Cingolani 3 , Richard Jackman 1
1 Pharmacology/LMP (NPP), UCL, London United Kingdom, 2 LCN, UCL, London United Kingdom, 3 LMCB-MRC, UCL, London United Kingdom
Show AbstractPrimary neuronal cells require specially treated surfaces for attachment, neurite growth and formation of neuronal networks. Typically surfaces coated with extracellular matrix (ECM) proteins are used to provide a suitable culture environment.Here we investigated the suitability of nanodiamond (ND) monolayers to promote attachment and growth of functional primary vertebrate neuronal networks. Neurons were cultured on ND-coated glass and compared to those on ECM protein-coated surfaces. The novel ND-coating promoted neuronal attachment and outgrowths equally well to Laminin/p-Ornithine (LN/p-Orn) coating. No attachment and growth was observed on uncoated cover slips.To test the universality of ND-coating we applied the coating process to nanocrystalline diamond, polycrystalline diamond and silicon substrates. On all substrates that we tested our neuronal cultures strictly required a coated surface, and we observed a comparable performance of ND-coating and LN/p-Orn coating. The combination of ND with ECM protein coating did neither result in enhanced attachment and growth, nor in negative interference. Neuronal excitability, synaptic transmission and the ability to form interconnected functional networks were comparable in cultures on materials coated with our new process and the conventional LN/p-Orn coating.We conclude that ND coating provides an excellent growth substrate on all materials tested and eliminates the necessity of protein-coating, which promises great potential for chronic medical implants or 3D cultures.
3:00 PM - A8.2
Sub-bandgap Absorption of Boron-doped Diamond Nanowires for Matrix-free Laser Desorption/Ionization Mass-spectrometry Analysis of Small Biomolecules.
Yannick Coffinier 1 , Rabah Boukherroub 1
1 , Interdisciplinary research institute (IRI-CNRS), Université de Lille1, Villeneuve d'Ascq France
Show AbstractPrior to analyze compounds by mass spectrometry (MS), analytes should be ionized. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a technique of choice for MS analysis of non-volatile and thermolabile samples. MALDI allows the desorption/ionization of a wide variety of compounds, including polymers, peptides and proteins and their subsequent MS analysis. However, due to a competitive desorption of parasitic ions from the matrix, it is difficult to detect low molecular weight compounds (< 700 m/z) even though small biomolecules are known to play important role in regulating cellular functions, for biomarker discovery and disease diagnosis. To overcome these hurdles and enable desorption/ionization (D/I) of small molecules, surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) was developed. The technique relies on the use of inorganic matrices instead of organic ones, yielding low background signals and thus high ionization efficiency of small molecules. Recently, SALDI-MS benefited from the highly active research field in nanosciences. Nanostructured silicon substrates, germanium nanodots, gold and silver nanoparticles, carbon nanotubes, platinum nanoflowers, zinc oxide (ZnO) nanowires, and porous alumina have successfully been used as highly efficient matrices in SALDI-MS. Such nanomaterials offer several advantages over commonly used inorganic microparticles or organic matrices, including good properties of absorption in the UV spectral range, a large surface area to volume ratio, and existence of a large panel of strategies for their surface functionalization (Peterson et al., 2007). In this work, diamond nanowires (BDN) substrates, prepared by direct reactive ion etching (RIE) of polycrystalline or nanocrystalline boron-doped diamond were successfully used as new interfaces for the realization of matrix-free LDI and MS analysis of small biomolecules. By varying the etching parameters, diamond nanowires of different diameters and lengths are obtained. BDN are able to achieve a sub-bandgap adsorption when they are irradiated by a N2 laser (λ: 337 nm, 3.68 eV) allowing the D/I of analytes. The D/I efficiency on such BDN interfaces has been investigated by varying the laser fluence used during irradiation.The optimized BDN substrates’ morphology coupled to a controlled surface chemistry allowed desorption/ionization (D/I) of peptides with a detection limit of 10 femtomoles for the Neurotensin peptide. The performance of the BDN substrates for the D/I of small molecules was also tested for the detection of Verapamil, an antihypertensive agent, with a limit of detection of 0.2 attomole. MS analysis of other small molecules such as lipids, sugars and bovine serum albumin (BSA) digest products has also been investigated.Ref.: Dominic S. Peterson. “Matrix-free methods for laser desorption/ionization mass spectrometry”Mass spectrometry review, 2007, Vol. 26, p19-34.
3:15 PM - A8.3
Fabrication and In-vivo Evaluation of 3D Shaped Flexible B-NCD MEAs for Eye Implant Applications.
Philippe Bergonzo 1 , Alexandre Bongrain 1 , Emmanuel Scorsone 1 , Hugues Girard 1 , Amel Bendali 2 , Lionel Rousseau 3 , Gaelle Lissorgues 3 , Blaise Yvert 4 , Serge Picaud 2
1 , CEA LIST, Gif-sur-Yvette France, 2 Paris Vision Institute, , INSERM, Paris France, 3 , ESIEE-ESYCOM, Noisy le Grand France, 4 CNIC, CNRS , Talence France
Show AbstractElectrical stimulation of neurons is a recognised therapeutic approach for the treatment of several neurodegenerative pathologies. Here we focus on retina implant applications, i.e. to directly stimulate live retina cells using a diamond microelectrode array fabricated on a soft substrate material. Current technologies for retina implants only exhibit a limited number of pixels (e.g. 64 for the Argus implant). They demonstrated to be a solution to treat most frequent pathologies of photoreceptor degeneration causing blindness. However, the low pixel number only enables partial contrasts recognition.. To increase the pixel number on the dense retina network, one has to reduce the stimulation current levels, and diamond electrochemical properties and bioinertness make this material the ideal candidate. We have developed a novel strategy to fabricate diamond microelectrode arrays on soft substrates, using Boron doped Nanocrystalline diamond (BNCD) as active microelectrodes. Prototypes are made on polyimide, using a bottom-up patterning process, compatible with clean room fabrication methods, and transferred to a soft polymer via lift off techniques. The mechanical flexibility allows the implants to be used as subretinal stimulating arrays, directly in contact with bipolar cells. One of the added breakthroughs is that this approach has enabled the fabrication of 3D shaped implants, as we demonstrated they can enable better interfacing with retina cells. The possibility to fabricate such 3D shaped diamond microelectrode arrays is a real progress for eye implants and more widely for a number of neuroprosthesis approaches.We will present data showing the fabrication and test of novel retinal MEAs devices: using prototypes fabricated and implanted in rat eyes for over 11 weeks. This aims at demonstrating the suitability of the diamond soft structures with neuronal cell coupling, towards the viability of our approach. Further, 3D issues at the nanoscale are being evaluated towards the reduction of the stimulation currents. Ack: MEDINAS, ANR-07-TECSAN-014,
3:30 PM - A8.4
Diamond-on-polymer Microelectrode Arrays as Flexible Electrochemical Sensors.
Heidi Martin 1 , David Sabens 1 , Allison Hess 2 , Christian Zorman 2
1 Chemical Engineering, Case Western Reserve University, Cleveland, Ohio, United States, 2 Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio, United States
Show AbstractConductive diamond film patterns were selectively deposited on thermally treated silicon wafers. A polymer support with gold contacts was deposited around the patterned diamond through a bottom-up fabrication process, to create a diamond-on-polymer microelectrode array with ten individually addressable diamond electrodes. The array was released from the silicon substrate through chemical etch. By means of the release process, the smooth diamond nucleation surface became the active electrochemical surface. Initial cyclic voltammetry studies at slow scan rates (<300mV/sec) showed that the diamond-on-polymer structure formed a functional electrode, with the characteristic wide potential window (-2V to 2V vs. Silver/Silver Chloride) of polycrystalline diamond. The response also verified the nucleation surface of these diamond films exhibited analogous behavior at slow scan rates to the growth surface of similarly patterned films. At higher scan rates (over 2 V/sec), an unusually high baseline current was observed, which was due in part to the presence of a thin silicon oxycarbide layer on the nucleation surface. This dielectric layer, an expected result of the diamond nucleation process, was verified using depth profiling with XPS, having an estimated 5 nm thickness. The oxycarbide was then removed using a reactive ion etch, enabling electrochemical detection at higher scan rates. Mechanical testing of the diamond-on-polymer structure showed that the presence of the diamond pads did not affect the overall mechanical properties of the polymer; the electrode structure also remained intact upon bending. Additional electrochemical comparisons of the carbide-free and as-patterned diamond electrodes will be reported, including voltammetry analyses in several analytes including the ferrocyanide redox couple and dopamine.
A9: Transport in Diamond and Delta Doping
Session Chairs
Tuesday PM, November 30, 2010
Room 306 (Hynes)
4:15 PM - A9.1
Time-of-flight Characterization of Single-crystalline CVD Diamond with Different Surface Passivation Layers.
Kiran Kumar Kovi 1 , Saman Majdi 1 , Ian Friel 2 , Richard Balmer 2 , Jan Isberg 1
1 Division of Electricity, Department of Engineering Sciences, Uppsala University, Uppsala Sweden, 2 , Element Six Ltd, Ascot, Berkshire United Kingdom
Show AbstractThe electronic properties of diamond, e.g. a high band-gap and high carrier mobilities, together with material properties such as a very high thermal conductivity, chemical inertness and a high radiation resistance makes diamond a unique material for many extreme electronic applications out of reach for silicon devices. This includes, e.g. microwave power devices, power devices and high temperature electronics. It is important to have an effective passivation of the surface of such devices since the passivation determines the ability of the device to withstand high surface electric fields. In addition, the passivation is used to control the surface charge which can strongly influence the electric field in the bulk of the device. The time-of-flight (TOF) technique, also known as the transient current technique (TCT), has proven to be a powerful method to study the material quality of single-crystalline chemical vapor deposition (SC-CVD) diamond. Using this method, it is possible to measure sample parameters such as electron and hole drift mobilities, charge carrier lifetimes or saturation velocities. The TOF technique has also been adapted for probing the electric field distribution and the distribution of trapped charge. In this paper we present new data from lateral ToF studies of high-purity single crystalline diamond with different surface passivations. Silicon oxide and silicon nitride has been deposited on the diamond surface and is used for surface passivation. The effect of the passivation on charge transport is studied, and the results of different passivation materials and deposition conditions are compared experimentally.
4:30 PM - A9.2
Diamond Layers for High Frequency Devices: Towards a Higher Control of Boron Doping and Crystalline Quality.
Pierre-Nicolas Volpe 1 , Jean-Charles Arnault 1 , Nicolas Tranchant 1 , Julien Pernot 2 , Christine Mer 1 , Francois Jomard 3 , Phillippe Bergonzo 1
1 Department of Sensors, Signal and Information, CEA-LIST, Gif sur Yvette, Essonne, France, 2 Nanosciences, Institut Néel – CNRS & Université Joseph Fourrier, Grenoble, Isère, France, 3 , GeMaC - Université de Versailles Saint-Quentin, Meudon, Hauts de Seine, France
Show AbstractBoron doped (BD) diamond is a very promising material for high frequency applications like delta-doped transistors [1,2]. Such electrical devices are composed of a highly BD layer 1 to 2 nm thick ([B]>3×1020 at.cm-3) located between two intrinsic layers ([B]~ 5×1015 at.cm-3). The development of such device clearly implies an accurate control of the highly BD layer thickness, of the involved interfaces, and to keep the crystalline quality control of the intrinsic layers. The aim of this study is first to produce low BD layers with a high crystalline quality using low [B]/[C] ratios or feeding small amount of oxygen during growth as already showed by Volpe et al [3]. Our second motivation, was to investigate the precursor effect on boron incorporation in a large doping range (1016 at.cm-3 >[B]> 1021 at.cm-3 ) in (100) CVD diamond layers grown by MPCVD on Ib (100) (3×3×0.5 mm3) HPHT substrates using diborane (B2H6) or TriMethyl Boron (TMB, B(CH3)3) as doping gas. It will be shown that the doping efficiency of these two precursors is quite similar as long as growth rate is rather small (0.2 µm/h) and the [B]/[C] ratio lower than a few thousand of ppm. The influence of the precursor has been also studied in the low boron doping range ([B] < 1017 at.cm-3). Two ways to decrease the boron doping in the layer have been checked using a gas mixture with a very low [B]/[C] ratio or feeding small amount of oxygen in the gas mixture as mentioned in [3] which permits, for diborane, to decrease the boron doping and to obtain low boron doped layer ([B] = 10 16 at.cm-3) with a hole mobility of 1900 cm 2 /Vs at 300K. However, some authors [4] showed possible boron atoms compensation by oxygen for TMB used as doping gas. This point has been investigated in our study by checking the evolution of the boron incorporation and the layer crystalline quality for several [O 2]/[H 2] ratios. The layers crystalline quality, doping level and transport properties have been characterised by SIMS, low temperature Cathodoluminescence (CL) analysis and Hall Effect measurements. Planar Aluminium Ring Shape diodes were synthesized and Current-Voltage as well as Capacitance-Voltage characteristics were also performed.[1] H. El-Hajj, A. Denisenko, A. Kaiser, R.S. Balmer, E. Kohn, Diamond & Related Materials 17, 1259–1263 (2008).[2] RS.Balmer et al, Phil. Trans. Royal. Soc. A 366, 251 (2008).[3] PN.Volpe, J.Pernot, P.Muret, F.Omnes, Appl. Phys. Lett. 94, 092102 (2009).[4] Z.Remes, M.Nesladek, P.Bergonzo, J.Barjon,et al , phys. Stat. Sol. A, 204, 2950 (2007).
4:45 PM - A9.3
δ-doped Diamond (111) Devices for the Realisation of Biosensors for Cancer Agents.
Robert Edgington 1 2 , Syunsuke Sato 1 , Kyosuke Tsuge 1 , Yuichiro Ishiyama 1 , Tasuku Ono 1 , Shinya Kitagoh 1 , Hiroshi Kawarada 1 , Rezal Ahmad 2 , Richard Jackman 2
1 School of Science and Engineering, Waseda University, Tokyo Japan, 2 London Centre for Nanotechnology, University College London, London United Kingdom
Show AbstractDelta-doping diamond is a technique where an ultra-thin layer (~1nm) of diamond is highly doped (>1020cm-3) with boron in order to achieve carriers of little thermal activation and high carrier mobility [1]. It is proving to be promising for realising high power and high frequency devices; however, its electrical properties also make it an ideal substrate for FET-type biosensors. Diamond forms highly stable biomolecular functionalisations [2] and exhibits highly controllable adsorption, and H-terminated Diamond FET-type biosensors have already demonstrated exceptionally high-selectivity and sensitivity [3]. Unfortunately the hydrogen-terminated conductive channel used in such devices is unstable, and the freedom to covalently functionalise the diamond surface is limited whilst having to preserve the conducting hydrogen-terminated surface. Delta-doping presents a solution to these problems whilst retaining the desirable properties of diamond FET biosensors by using a stable, boron delta-doped diamond layer as its conductive channel, leaving its channel and gate surface free for any desired surface functionalisation. However, the generation of such δ layers is technologically demanding and only low mobility structures have been reported to date. Whilst most work has been carried out on (100) diamond, we have found high doping densities can be achieved on (111) planes, and herein report upon the fabrication of the first diamond (111) δ-doped layers on single crystal diamond substrates. Characterisation has been performed using Hall effect measurements and impedance spectroscopy; which we have previously shown to be a powerful method for measuring parallel conduction paths in δ-structures [4].Following characterization, the (111) delta-doped diamond substrates have been fabricated into solution gate field effect transistors (SGFET), where the delta-doped channel is in direct contact with the solution. The resulting SGFETs have been subsequently functionalized with aptamers and used to demonstrate the aptamer-based potentiometric biosensing of the Platelet-Derived Growth Factor (PDGF) protein, which is one of the numerous growth factors that regulate cell growth and division. It plays a significant role in blood vessel formation (angiogenesis), and uncontrolled angiogenesis is a characteristic of cancer [5]. The methods used for functionalising the diamond will be described, and the initial results achieved with aptamers for biosensing reported.[1] El-Hajj et al Diam Relat Mater (2008)[2] Yang et al Nat Mater (2002) vol. 1 (4) pp. 253-257[3] Kuga et al J Am Chem Soc (2008) vol. 130 (40) pp. 13251-13263[4] Tumilty et al Appl. Phys. Lett. (2009) vol. 94 (5)[5] Cerchia et al FEBS letters (2002)
5:00 PM - A9.4
Evaluation of NIS Tunneling Junction Fabricated by Superconducting Diamond.
Ryo Nomura 1 , Shinya Kitagoh 1 , Megumi Watanabe 1 , Ryusuke Kanomata 1 , Shinichirou Kurihara 1 , Yoshihiko Takano 2 , Takahide Yamaguchi 2 , Hiroshi Kawarada 1
1 Faculty of science and engineering, Waseda University, Okubo, Tokyo Shinjuku, Japan, 2 , National Institute for Materials Science, Tsukuba Sengen, Ibaraki, Japan
Show AbstractOn superconducting diamond, we have fabricated Normal conductor-Insulator-Superconductor (NIS) tunneling junctions and measured these characteristics for the first time. The current –voltage (I-V) and conductance-voltage (dI/dV-V) characteristics of junctions depend on the particular energy gap of superconductor called superconducting gap (Sgap) and voltage gap (Vgap) expressed in Sgap/e. The Fermi energy of superconductor corresponds to that of normal conductor, but the Sgap arises a few meV above and below the Fermi energy below the critical temperature (Tc). In this research, NIS tunneling junction was fabricated on heavily boron doped (111) diamond whose Tc of zero resistance is around 9K[1], so the Vgap at 0K is expected to be nearly 1.35mV, which is calculated from the empiric formular Vgap = 3.52kBTc/e. The Vgap was clearly observed in the I-V characteristics at 2.0K and its temperature dependence. The gradient of I-V characteristic changed around 1.3mV at 2.0K which represents the existence of the Sgap. It is in agreement with the theoretical value and the characteristic became linear with temperature increase due to Sgaps decrease. The Sgaps was also observed in the conductance-voltage (dI/dV-V) characteristics. It arises symmetrically above and below of Fermi energy, so the dI/dV -V curves are symmetrically centering around zero voltage. The Vgap is the voltage between the two conductance maximum points. The characteristics of I-V and dI/dV-V were both similar to theoretical characteristics. For the first time the Sgap of superconducting diamond from I-V characteristics has been obtained. This is the most fundamental way to observe Sgaps. While the Sgap of superconducting diamond was measured by other methods (ex.scanning tunneling microscopy/spectroscopy (STM)[2,3], laser-excited photoemission spectroscopy (PES)[4]) carried out in low Tc samples[2,3], the Sgap is more directly observed in NIS tunneling junction fabricated in higher Tc of superconducting diamond. The most reliable Sgap has been obtained by homogeneously boron-doped diamond films in this research.[1] S. Kitagoh, H.Kawarada, et al., Physica C (in press)[2] T.Nishizaki, H.Kawarada et al., J. Phy. Chem. Solids, 69, 3027-3030 (2008)[3]T. Nishizaki, Y. Takano, M. Nagao, T. Takenouchi, H. Kawarada, N. Kobayashi “Low-temperature STM/STS studies on boron-doped (111) diamond films”, J. Phy. Chem. Solids, 69, 3027-3030 (2008)[4] K.Ishizaka, H.Kawarada, S.Shin, et al., Phys. Rev. Lett. PRL 98, 047003 (2007)
5:15 PM - A9.5
The Electrical Evaluation of Diamond FETs with Boron-delta-doped Channels.
Tasuku Ono 1 , Kyosuke Tanabe 1 , Robert Edgington 1 , Hiroshi Kawarada 1
1 , University of Waseda, Tokyo Japan
Show AbstractAs a solution gate diamond FETs with good on-off characteristics, boron-doped channels with oxygen termination are being proposed for the first time in this work to realize stable diamond FETs for use in these extreme conditions. In general the drain current density of diamond FETs with boron-doped channels have been found to be more than one order of magnitude less than that of hydrogen-terminated Diamond FETs,where a relatively high carrier density of 1-5×1013cm-2 can be modulated effectively by surface states-free H-termination. One of the reasons for poor boron doping channel is its low carrier concentration caused by boron’s deep acceptor level (0.37eV) in diamond. To fully activate boron at room temperature one has to dope diamond with boron by more than 3×1020cm-3[1], resulting in the formation of an impurity band in diamond. However, in the range of electric field modulation that is necessary for an FETs operation caused by surface potential control by external voltage, it’s hard to achieve current saturation and pinch off when surface carrier density is more than 1×1014cm-2. Therefore, a delta doping technique where local volumetric carrier density satisfying 3×1020cm-3 with surface carrier density less than 1×1014cm-2 is needed to deposit by highly-doped boron layers under 10nm in order to make the surface carrier density below 1×1014cm-2. To this end boron-doped diamond solution gate FETs have been fabricated on diamond substrates, where the delta doped boron channel surfaces are in direct contact with the electrolyte solution. A 1nm boron doped layer has been grown as a delta doped FET channel by microwave plasma chemical vapor deposition (MPCVD) and subsequently oxygen terminated. Partailly oxygen termination with the coverage of 20 % was carried out by ozone treatment. Titanium was deposited on boron-doped Source/Drain and annealed under vacuum at 500 K for 30 min to form a titanium carbide (TiC) layer. The TiC forms an shallow contact [2] on the B-doped channel reducing contact resistance between Source/Drain electrodes and B-doped channel. Moreover, TiO2 - formed homogeneously by natural oxidation - serves as a chemically stable electrode passivation [3].Maximum drain current densities of 8mA/mm were obtained for an SGFET (channel length of 500um and width of 8mm, applied gate voltage of 1.4V) and the maximum transconductance was 0.027mS/mm Those properties are comparable to H-terminated diamond SGFETs in the same gate length. *This research was partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research(S)[1]A.Kawano, H.Kawarada et al. Phys. Rev. B (in press)[2]Y.Jingu, H.Kawarada et al. IEEE Trans. Electron Devices 57 (2010) 966-972[3]K.Tanabe, H.Kawarada et al: JSAP 57 (2010) 17a-ZD-11
Symposium Organizers
Philippe Bergonzo CEA-LIST
Commissariat Energie Atomique (CEA/Saclay)
James E. Butler (Retired from Naval Research Laboratory)
Christoph E. Nebel Fraunhofer Institut fuer Angewandte Festkoerperphysik
Andrew T. S. Wee National University of Singapore
Milos Nesladek Hasselt University & IMEC vzw
A10: Crystal Growth: cBN and Diamond
Session Chairs
Wednesday AM, December 01, 2010
Room 306 (Hynes)
9:30 AM - **A10.1
Recent Advances in Cubic Boron Nitride Films.
Wenjun Zhang 1 , Qing Ye 1 , Yang Yang 1 , Bin He 1 , Yat Ming Chong 1 , Xiaojun Pan 1 , Igor Bello 1 , Shuit-Tong Lee 1
1 Center Of Super-Diamond and Advanced Films (COSDAF), and Department of Physics and Materials Sciences, City University of Hong Kong, Hong Kong Hong Kong
Show AbstractCubic BN (cBN) has a set of extreme properties similar or even superior to diamond, which makes cBN a very promising material for applications in cutting tools, thermal, optical, and high-temperature and high-frequency electronic devices. Cubic BN is a synthetic material, and the study on the synthesis and characterization of cBN started in the early 1960s. To date, cBN has been commercially synthesized in large quantities as powders with sizes ranging from submicron to millimeters by a high-pressure high-temperature (HPHT) method. Abrasive cBN powders are usually cemented by metal binders and formed to pre-fabricated tools of various shapes. Together with HPHT diamond, HPHT cBN has a billion dollars market especially in cutting tools and wear parts. The severe nature of the HPHT methods and the limited size of cBN grains produced, however, have prohibited many attractive potential applications of cBN. Recently remarkable progresses especially in improving crystallinity and film adhesion, understanding nucleation and growth mechanism, and tuning electrical properties have been obtained. This presentation will review the recent advances in the following aspects: 1) Growth techniques and interface engineering to improve film quality and adhesion; 2) Tribology of boron nitride films and their dependence on phase composition and surface roughness; 3) Modification of the electronic properties of cBN films by in situ and post-growth doping techniques; and 4) New developments of cBN films in the applications of mechanical, electronic, and optoelectronic devices.
10:00 AM - A10.2
Fabrication of Semiconducting Cubic Boron Nitride Films on CVD Diamond by Ion-beam Assisted Sputtering.
Kenji Ueda 1 , Hidefumi Asano 1
1 Graduate School of Engineering, Nagoya University, Nagoya Japan
Show AbstractDiamond has excellent physical properties, such as the highest thermal conductivity, high electric breakdown field, high chemical stability, etc. These are advantageous for high-power electronic devices. One essential technology for diamond electronic devices is p- and n-type doping. However, n-type doping is extremely difficult for diamond. The activation energy (Ea) of typical n-type dopants such as phosphorus (Ea= ~0.6 eV) is too high to generate free carriers at room temperature. High-quality homojunctions of diamond are hardly fabricated because of poor n-type doping. Instead of finding new n-type dopants with small Ea, we consider another way to fabricate high quality p-n junctions using diamond, that is, substitution of n-type diamond layers in diamond homojunctions with n-type cubic boron nitride (c-BN) layers. Cubic BN is regarded as a suitable layer to fabricate heterojunctions with diamond because it has resemble crystal structure and close lattice constant (a=0.3615 nm) with diamond (a=0.3567 nm) and because the Ea of n-type Si-doped c-BN (Ea= ~0.24 eV) is much lower than that of phosphorus doped diamond. In this study, as a former stage for fabricating diamond/c-BN heterojunctions, we tried fabricating semiconducting c-BN films on CVD diamond. BN films were formed by using ion-beam assisted sputtering (IBAS) method. Two ion sources were used for IBAS; one of the ion sources is for sputtering of boron targets with 1 keV Ar ions, and the other source is used for irradiating with low energy N2 and Ar ions to grow c-BN films. The substrate temperature (TS) was varied from 400 to 600°C. Fourier transformed infrared (FT-IR) spectroscopy was applied to estimate the volume fraction of cubic phase. Hall measurements were performed using the van der Pauw method with Au/Ti layers as ohmic electrodes. In IR spectra of the BN films, strong absorption peaks were observed at 1060 cm-1, which corresponds to the sp3 bond of c-BN, and 1370 and 700 cm-1, which correspond to the sp2 bond of hexagonal (h-) BN. These peaks increased as the TS increased. The volume fraction ratio of c-BN estimated from intensity ratio (I1060/( I1060+ I1370)) was 50-60%, which is independent of the growth temperature. The BN films formed at TS of 500°C showed n-type conductivity with carrier concentration of 2 x 1018 cm3 and mobility of 21 cm2/Vs at room temperature from Hall measurements. The origin of n-type conductivity is not clear, however we think this is due to nitrogen deficiency and/or unintentionally doped impurities such as C, Si, etc. in boron targets.
10:15 AM - A10.3
Growth of Low Defect Heteroepitaxial Diamond Films by Epitaxial Lateral Overgrowth on Stripe Patterned Nucleation.
Shun Washiyama 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 AbstractHeteroepitaxy of diamond is one of the most promising strategy for realization of large-area, mono-crystalline diamond films. However, the lattice defects such as misfit dislocation is included because of the large lattice misfit between diamond and the substrate. We have already shown that coalesced epitaxial lateral overgrowth (ELO)-diamond layers on iridium (Ir) substrate exhibited continuous surface morphologies with macro-step structure without any observed growth interruption at the coalescence boundaries. As a result, it is found that heteroepitaxial diamond films having high crystallinity could be obtained by ELO technique. In this study, we characterized the effect of ELO in heteroepitaxial diamond films. Two different orientations of diamond nucleation stripes along <100> and <110> directions were simultaneously formed on the single (001) Ir/MgO substrate. The width and separation distance of stripes were 3 μm and 20 μm respectively. The ELO-diamonds were grown by direct-current plasma chemical vapor deposition (DCPCVD) at 1250 K and 120 Torr. The defect density is examined by hydrogen plasma etching at 1200 K.The inverted pyramidal shaped etch-pits were observed on ELO-diamond surface. The density of etch pit was approximately 107cm-2 in both stripe directions with 20 μm separation distance of stripe, and this value is lower than that on conventionally grown heteroepitaxial diamond (108cm-2). These pits might be originated from the threading dislocations. This result suggests that the ELO is an effective technique for the reduction of threading dislocations in heteroepitaxial diamond films. The additional results obtained by cathode luminescence (CL) will be presented, and the effect of ELO will be discussed relating to the growth manner of heteroepitaxy.
10:30 AM - A10.4
Nanostructuring of the Ir (001) Surface for Epitaxial Diamond Film Growth.
Murari Regmi 1 , Gyula Eres 1 , Karren More 1
1 , Oak Ridge National Lab, Oak Ridge, Tennessee, United States
Show AbstractIn this work we describe recent results using substrate biasing for preparing nanostructured Ir (001) surfaces that promote heteroepitaxial diamond film growth. Although this step is referred to as “bias enhanced nucleation” actual diamond nucleation and film growth on these surfaces occur in a subsequent step after substrate bias is turned off. We study the evolution of the (001) Ir surface structure on yttria-stabilized zirconia films deposited on Si(001) wafers by systematically varying the bias voltage, bias time and the methane concentration in a microwave chemical vapor deposition (MWCVD) system. A distinct feature of this process is that the window for the formation of the Ir (001) surface structure that promotes high density epitaxial diamond nucleation (>1011 cm-2) is very narrow. Below -100 V bias, the Ir surface remains unchanged. Above this value the formation of nanostructures with characteristic features is observed. The geometry and density of these features depends strongly on the magnitude of the bias voltage, bias time and the methane concentration. Although no diamond nucleation occurs during substrate biasing, a minimum methane concentration of 1.5% is necessary to produce a surface structure that favors diamond nucleation and growth after substrate bias is turned off. The areal density of so called domains consisting of clustering of surface features where highly oriented epitaxial diamond nucleation occurs is a function of bias time. With increasing bias time the domain density increases leading to coalescence of domains and uniform domain coverage for 60 minutes of bias time. We show that the formation of uniform domain coverage is a prerequisite for high quality heteroepitaxial diamond film growth.
A11: Diamond Biosensors
Session Chairs
Wednesday PM, December 01, 2010
Room 306 (Hynes)
11:15 AM - **A11.1
Diamond as an Ultra-stable Platform for Biologically Selective Surfaces: From Proteins to Cells.
Robert Hamers 1 , Tami Lasseter Clare 8 , James Butler 2 , Adarsh Radadia 3 6 , Hongjun Zeng 7 , William King 5 6 , John Carlisle 7 , Rashid Bashir 3 4 6 , Courtney Stavis 1
1 Dept. of Chemistry, University of Wisconsin, Madison, Wisconsin, United States, 8 Dept. of Chemistry, Portland State University, Portland, Oregon, United States, 2 , US Naval Research Laboratory, Washington , District of Columbia, United States, 3 Dept. of Electrical and Computer Engineering, Univ. of Illinois, Urbana, Illinois, United States, 6 Micro and Nanotechnology Laboratory, Univ. of Illinois, Urbana, Illinois, United States, 7 , Advanced Diamond Technology, Romeoville, Illinois, United States, 5 Dept. of Mechanical Science and Engineering, Univ. of Illinois, Urbana, Illinois, United States, 4 Dept .of Bioengineering, Univ. of Illinois, Urbana, Illinois, United States
Show AbstractThe remarkable chemical stability of diamond makes it an attractive substrate for biological interfaces for applications in biomedicine and biosensing. In these environments a key challenge is achieving a high degree of selectivity, binding biological species of interest while rejecting others. Photochemical grafting of oligo(ethylene glycol) oligomers has emerged as an excellent way to produce highly stable surfaces that will resist the binding of fibrinogen and other proteins. Here, we describe recent experiments comparing the use of different for their ability to resist binding of fibrinogen and other proteins, and compare the result with oligomers of different lengths and diamond samples with different roughness, including diamond thin films and single-crystal samples.By using bifunctional molecules to link antibodies to the surface, we have recently demonstrated the ability to make surfaces that will selectively bind to specific types of cells. Using the E. coli K12 strain as a model system, we have investigated how different surface attachment strategies impact the resulting properties of the antibody-modified diamond samples. XPS and FTIR are used as diagnostics to probe the density and conformation of antibodies at the surface, and compared with the resulting efficiency and specificity of binding to glean insights into the chemical factors that control specificity of binding to biological species at diamond surfaces.
11:45 AM - A11.2
Diamond Functionalization Based on Amine Chemistry Applied to Dual Electrochemical and MEMS Biosensing.
Charles Agnes 1 , Sebastien Ruffinatto 2 3 , Alexandre Bongrain 1 , Emmanuel Scorsone 1 , Jean-Charles Arnault 1 , Franck Omnes 2 , Pascal Mailley 3 , Philippe Bergonzo 1
1 LCD, CEA-LIST, Gif-sur-Yvette France, 2 Institut Néel, CNRS, Grenoble France, 3 INAC, CEA, Grenoble France
Show AbstractDiamond is recognized as a promising material for the fabrication of bio-transducers. When heavily doped with boron (BDD), it behaves like a metal interface that withstands corrosion and exhibits superior electrochemical properties such as low background currents, wide potential window and insensitivity to oxygen evolution. It is also biocompatible, and its carbon surface suitable for selective grafting of functions on its surface, thus opening the route towards electroanalysis and interfacing (bio)molecular entities for biosensor fabrication.Here we focus on the grafting of specific biomolecules on the diamond surface. We have developed and patented a process that is fast, selective, leading to monolayers, and compatible with patterning approaches. We have used it successfully for the fabrication of a second generation amperometric enzymatic biosensor based on iridium oxide (IrOx) nanoparticles e.g. for glucose detection. This model is here based on glucose oxidise (GOx) grafting and can also be used for several other systems (glutamate etc). The approach has also been successfully used on diamond MEMS (cantilevers) for subsequent measurements combining electrochemical selective adsorption and mass detection. For example, it was made possible to detect the variations of the surface stress induced on caproic acid monolayer grafted using the amine approach on a diamond cantilever: we will show that the simple pH driven modification from –COOH to –COO- termination induces strong resonant frequency shifts, thus demonstrating the high sensitivity of this dual approach for fine monitoring of the amine chemistry grafting route.
12:00 PM - A11.3
Functionalized Ultra-Nanocrystalline Diamond (UNCD) Films For Pathogen Sensing.
Adarsh Radadia 1 , Courtney Stavis 2 , Yi-Shao Liu 1 , Natalya Privorotskaya 4 , Hongjun Zeng 3 , John Carlisle 3 , William King 4 , Robert Hamers 2 , Rashid Bashir 1
1 Micro and Nano Technology Labs, University of Illinois, Urbana, Illinois, United States, 2 Dept of Chemistry, Univeristy of Wisconsin, Madison, Wisconsin, United States, 4 Mechanical Science and Engineering, University of Illinois, Urbana, Illinois, United States, 3 , Advanced Diamond Technologies, Romeoville, Illinois, United States
Show AbstractUNCD films consist of 2-5 nm phase-pure diamond grains and are attractive for conformal coating of micro-/nano-structures for biosensing applications. The objective of this paper is to show that UNCD surfaces can be used for specific pathogen capture when functionalized with a biorecognition element like an antibody. Here we show that UNCD surfaces can be functionalized via bovine serum albumin (BSA)-streptavidin-biotin non-covalent chemistry or covalent functionalization procedure. We show that a heated silicon microcantilever surface can be conformably coated with a UNCD film and functionalized with heat shock protein Hsp60 (using the non-covalent chemistry) for selective capturing and lysing Listeria monocytogenes V7. The non-covalent functionalization chemistry is based on the strong physisorption of BSA to UNCD surface, however eventually the non-covalently bound molecules are prone to desorption. In contrast, covalent immobilization helps prevent the eventual desorption of protein. Previous work has shown that UV-alkene chemistry on nanocrystalline diamond is more resistant to temperature and electrically mediated compared to silicon, silica, and gold [1,2]. Here we use the UV-alkene chemistry to tether E.coli O157:H7 antibodies to the UNCD surface and show that antibody modified UNCD films acts as efficient pathogen capture surfaces compared to silanized silica surface.[1] Wang, J.; Carlisle, J. A. Diamond and Related Materials 2006, 15, 279-284.[2] Yang, W. S.; Auciello, O.; Butler, J. E.; Cai, W.; Carlisle, J. A.; Gerbi, J.; Gruen, D. M.; Knickerbocker, T.; Lasseter, T. L.; Russell, J. N.; Smith, L. M.; Hamers, R. J. Nature Materials 2002, 1, 253-257.
12:15 PM - A11.4
TiO2 Encapsulated Source/Drain and Gate Electrodes for Miniaturized Diamond Solution Gate FETs.
Kyosuke Tanabe 1 , Yuichirou Ishiyama 1 , Hiroshi Kawarada 1
1 , Waseda University, Tokyo Japan
Show AbstractIn diamond solution gate field effect transistors (SGFETs) different from Si ion sensitive (IS) FET, gate insulating film is not required[1], Biomolecules can be bounded on sensing surface closer, and sensitive detection becomes possible [2,3]. During a number of DNA hybridization and denaturation cycles on the diamond surface, both reversible changes in gate potential were very reproducible throughout a series of measurements [2,3]. But electrode passivating film to prevent leakage current between source/drain electrode and reference electrode is necessary. Previously, we fabricated SGFETs used gold as source/drain electrode and used epoxy resin or resist for the encapsulation of the electrodes. But there was a problem that encapsulation becomes thicker and the epoxy resin is not suitable for miniaturization . Here we propose SGFETs using titanium (Ti) as electrode [4] and its native oxide (TiO2) as protective film for the first time. Very thin TiO2 is formed on the Ti source/drain electrode surface, so that the channel surface can be miniaturized. It is possible to reduce the fluctation in device characteristics leading to the integration of many devices TiO2 is also biocompatible and chemically stable, so it has excellent properties of bio materials. We have succeeded in the miniaturization of the SGFET down to 1.5um gate length and the highest transconductance (gm) of 11.4mS/mm was obtained in SGFETs. From the gate length dependence of gm, the capacitance of the electric double layer was evaluated to be 11uF/cm2 assuming the cahnnel mobility of 4 cm2/Vs. The reasonable electric double layer capacitance was obtained and it is found that the SGFET operates in a MOSFET mode with electric double layer as gate capacitor.We have also created two-dimensional structure SGFETs (in-plane SGFETs) which have the gate electrode (Ti) with gate insulator (TiO2) on diamond surface for the first time. Although conducting channel surface is hydrogen-terminated having the accumulated holes on the surface, the surface near the Ti gate electrode is electrically isolated by strong oxygen-termination.The fabricated devices were working properly without any gate leakage current. Without reference electrode, the device was found to be possible to control the current by gate voltage. Since the in-plane SGFETs can be fabricated, device integration and μ-TAS applications can be expected using Ti.electrode process on diamond.[1] H.Kawarada et al:Phys.Status Solidi A 185,79,2001.[2] K.S.Song, H.Kawarada et al:Phys.Rev.E.74,041919,2006.[3]S.Kuga,H.Kawarada et al:J.Am.Chem.Soc.130,13251,2008.[4] Y.Jingu, H.Kawarada et al. IEEE Trans. Electron Devices 57, 966, 2010.
12:30 PM - A11.5
Optimization of a Boron Doped Nanocrystalline Diamond Temperature Regulator for Sensing Applications.
Tim Clukers 1 2 , Bart Van Grinsven 1 , Thijs Vandenryt 1 2 , Stoffel Janssens 1 , Patrick Wagner 1 3 , Ward De Ceuninck 3 1 , Ronald Thoelen 2 1 , Michael Daenen 2 1 , Ken Haenen 1 3
1 Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Limburg, Belgium, 2 , Xios University College Limburg, Diepenbeek, Limburg, Belgium, 3 Division IMOMEC, IMEC vzw, Diepenbeek, Limburg, Belgium
Show AbstractWithin the idea of creating a boron doped nanocrystalline diamond (B-NCD) based temperature regulator for bio-sensing applications the concept was proven to work, even exceeding the necessary specifications to create a temperature-stable environment [1] The stabilized environment should enable the monitoring of the hybridization and denaturation of DNA covalently bonded onto a diamond surface. In this work the temperature control is achieved by using the boron doped nanocrystalline diamond film as a thermistor and heater at the same time in combination with a PID-control. With this concept it is possible to create a temperature control, with possible setpoints going from room temperature till 70°C, with an accuracy exceeding a maximum temperature variation of 0.02°C. While the first prototype made use of a reference temperature sensor, the ongoing research using this temperature control works fully autonomous following the spirit of creating a handheld device. Parallel with steering the temperature, by varying the current through the B-NCD film, the resistance of the B-NCD film is measured with a 4-point measurement from which the temperature can be derived using a calibration curve. This value is the feedback for the PID-control to steer the current used for the regulation. Once the control is fully integrated onto the temperature control setup, measurements using DNA samples can be executed with a higher accuracy and faster than is possible with the currently available installation.[1] T. Clukers, B. Van Grinsven, T. Vandenrijt, S.D. Janssens, P. Wagner, W. De Ceuninck, R. Thoelen, M. Daenen, K. Haenen, “Boron doped nanocrystalline diamond temperature regulator for sensing applications”, submitted to physica status solidi (a) (2010).
A12: Diamond MEMS and Novel Gas Sensors
Session Chairs
Wednesday PM, December 01, 2010
Room 306 (Hynes)
2:30 PM - **A12.1
Dissipation and Applications of Nanocrystalline Diamond MEMS and NEMS.
Matthias Imboden 1 , Alexei Gaidarzhy 1 , Guiti Zolfagharkhani 1 , Diego Guerra 1 , Tyler Dunn 1 , Pritiraj Mohanty 1
1 Physics, Boston University, Boston, Massachusetts, United States
Show AbstractMicro- and Nanoelectromechanical systems (MEMS and NEMS) are establishing themselves as a viable commercial technology and are becoming more and more prevalent in industrial applications. Current uses range from gyroscopes, to timing oscillators and accelerometers, among others. Devices are becoming smaller, faster and more sensitive; in addition fictionalization and hybrid structures make this emerging technology suitable for biological applications as well. As tools for basic research MEMS and especially NEMS have demonstrated extraordinary sensitivity to external forces, allowing for example, the detection of electron spin flips, single molecules, and even macroscopic quantum states.Here nanocrystalline diamond (NCD) is presented as an alternative device material to silicon for MEMS and NEMS applications. Diamond, well known for its extraordinary mechanical properties, such as being the hardest known natural material, is also biologically and chemically inert and radiation hard, making it an ideal candidate for many NEMS applications. Using CVD growth processes, diamond thin films can be grown to engineer novel NEMS devices. Material properties including resistivity and surface roughness can be tuned controllably.Here, MEMS and NEMS performance is discussed in doubly clamped structures with emphasis on dissipation at both room temperature and sub Kelvin temperatures. The dissipation characterizes the losses associated with resonant motion and ultimately determines the device sensitivity and bandwidth, and is hence of great importance to most applications. Understanding sources and magnitudes of dominant dissipative mechanisms is essential in the further establishment of NCD as a viable NEMS material.We present dissipation measurements for a range of device sizes and frequencies ranging from 5 MHz to over 1 GHz at room temperatures as well as cryogenic temperatures. Frequency and dissipation scaling laws for doubly clamped diamond resonators are demonstrated [1,2]. In the Kelvin to millikelvin-temperature parameter space, measurements of dissipation and frequency shifts in megahertz-range resonators indicate the presence of two level systems (TLS) as the dominant source of dissipation [3].Finally, applications of NEMS are demonstrated, illustrating a range of phenomena such as mechanical switching and a GHz frequency device that is monitored through non-linear mode coupling to a low frequency resonance [4].[1] M. Imboden, A. Gaidarzhy, P. Mohanty, J. Rankin, and B.W. Sheldon, Scaling of dissipation in megahertz-range micromechanical diamond oscillators, Appl. Phys. Lett., 90, 173502 (2007)[2] A. Gaidarzhy, M. Imboden, P. Mohanty, J. Rankin, and B.W. Sheldon, Appl. Phys. Lett. 91, 203503 (2007)[3] M. Imboden, P. Mohanty, Evidence of universality in the dynamical response of micromechanical diamond resonators at millikelvin temperatures, Phys. Rev. B 79, 125424 (2009)[4] To be published
3:00 PM - A12.2
High-frequency Low-impedance Piezoelectric MEMS Resonators Realized Using Polished Ultrananocrystalline Diamond (UNCD) Substrates.
John Carlisle 1 , Hediyeh Fatemi 2 , Hongjun Zeng 1 , Reza Abdolvand 2
1 , Advanced Diamond Technologies, Inc., Romeoville, Illinois, United States, 2 Electrical and computer engineering, Oklahoma State University, Tulsa, Oklahoma, United States
Show AbstractHigh frequency and low motional impedance lateral bulk-mode resonators are fabricated integrating ultrananocrystalline diamond thin films with highly oriented aluminum nitride. A ~56Ω 860MHz lateral mode thin-film piezoelectric-on-diamond (TPoD) resonator is reported and methods to further reduce the motional impedance at high frequencies will be discussed. Diamond as a structural material has received a lot of attention in the MEMS community due to its unique properties such as highest natural Young's modulus (for acoustic devices), biocompatibility (for in vivo biosensors), and chemical inertness (for harsh environment applications). Thin-film piezoelectric-on-diamond (TPoD) lateral bulk-mode resonators with as high as 80% improvement in frequency over the same devices fabricated on silicon substrate has shown much promise in scaling the resonant frequency beyond the limits achievable by silicon. In these devices the piezoelectric transduction is the key to achieving low impedance without the need for large bias voltages and extremely narrow hard-to-fabricate gaps (required for capacitive devices). Also, the substrate is a low-loss acoustic media which provides for improved quality factor, power handling, and structural integrity. In order to sputter a highly-oriented piezoelectric film on the relatively rough surface of the diamond substrate, a polished buffer layer (e.g. oxide) was previously used. However, this layer was identified as a barrier for realization of very high frequency resonators since the presence of the oxide would significantly alter the mode shapes. In this work the surface roughness of the diamond substrate is substantially reduced by depositing ultrananocrystalline diamond (UNCD) and subsequent polishing. Therefore, in this work, the stack of Mo/AlN/Mo is directly sputtered on the diamond, which greatly improves the coupling between the AlN as the electromechanical transducer and the diamond as the resonant body. Also, the AlN’s FWHM is improved to ~4.2 compared to 12 measured for the AlN sputtered on unpolished diamond. In order to achieve low motional impedance at high frequencies, we take advantage of larger actuation areas by increasing the resonant mode. A 21st order lateral bulk-mode resonator was designed and fabricated on both a polished UNCD and a SOI substrate. The resonance frequency on UNCD is almost 1.6 times the frequency on a 4µm thick silicon substrate. The resonator is supported with 9 tethers to subdue the spurious modes as demonstrated. The quality factor of the resonator on diamond is about 2700 compared to 1500 for the same device on Silicon. The motional impedance was measured to be 56 Ω. Also, a temperature coefficient of frequency (TCF) of -9.6 ppm was measured, which is notably smaller than the reported values for silicon (~-29 ppm).
3:15 PM - A12.3
Nanodiamond Coated SAW Platform for High Sensitivity Detection of Warfare Volatile Chemicals.
Emmanuel Scorsone 1 , Emmanuel Chevallier 1 , Philippe Bergonzo 1
1 Diamond Sensors Laboratory, CEA Saclay, Gif-sur-Yvette France
Show AbstractSAW sensors are known as promising platforms for the detection of toxic volatile chemicals due to their high sensitivity. However, the selective coating (often a polymer) deposited on such transducers is generally a limiting element in terms of selectivity, sensor to sensor repeatability and long term stability. We have developed a novel approach where we use modified NanoDiamond particles (NDs) as an alternative sensitive layer solving several of the issues often encountered on such sensors. Indeed, NDs can be found in nanometre sizes and be deposited as single or multiple layers on a variety of sensor surfaces with uniform thicknesses and high surface area, which is in favour of high sensitivity. NDs also feature attractive properties for chemical detection: (i) they are made of sp3 carbon which is very stable in time, and (ii) the carbon terminated surface of diamond offers wide perspectives from organic chemistry and biochemistry for covalent attachment of specific receptors. The sensors were implemented in a very versatile detection platform consisting of a semi-industrial 8 channel SAW sensor system enabling high performance detection of gases or VOCs. In this contribution, we have optimised the NDs coatings for warfare gas detection. We report the detection of traces of dinitrotoluene, a precursor for the fabrication of TNT, and dimethyl methylphosphonate (DMMP), a simulant for sarin gas. We achieved detection thresholds in the low ppb range for both gases with high signal to noise ratio. The sensitivity for DNT was in the order of 200 Hz per ppb and over 5 Hz per ppb in the case of DMMP. Detection limits are below all values reported in the literature, together with improved stability, reproducibility and response time.
3:30 PM - A12.4
Nanodiamonds as a Platform for the Detection of Threat Signatures.
Rezal Ahmad 1 , Carolina Parada 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. The introduction of a chemically sensitive layer to a MEMS sensor can lead a measurable signal being generated in reaction to chemical stimuli. Cantilevers are typically made of single-crystal silicon due to the mature and reliable fabrication technology available with this material. 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 functionilised for sensing purposes. For example, photochemical chlorination, amination and carboxylation functionlisation processes have been widely demonstrated. A single crystal diamond-based cantilever structure has previously been reported, based on the application of FIB milling to pattern a free-standing cantilever in a single crystal diamond plate. However, the processing complexities and time associated with deploying these techniques limits 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.Nano-diamonds produced by detonation (DNDs) were suspended in deionised water and attached to Si cantilevers using sonication. Silicon structures in the form of an array of 8 cantilevers (length 450µm, width 90µm, thickness 0.9µm) were coated. The static and dynamic modes of the cantilever arrays were characterized using an AFM. The extracted spring constant (k) values show the pre-bent steady state of the cantilevers as a result of the DNDs mass loading effect. The k values increase by a factor of around 7. In dynamic mode, the resonant frequency prior decreases around 10% in the presence of the DNDs. Upon exposure to ammonia, the resonant frequency increases by around 1%. DNT, a sensing analogue of TNT (the explosive), could also be detected using these devices. The mechanism leading to these observations will be described in terms of the compressive and tensile stresses present within the DND coated Si cantilever. The prospects for the development of highly efficient cost-effective diamond-Si hybrid sensors for the detection of threatening vapours will be discussed.
A13: Transport in Diamond and Delta-doping
Session Chairs
Wednesday PM, December 01, 2010
Room 306 (Hynes)
4:15 PM - **A13.1
Fabrication and Characterization of Single-crystal CVD Diamond Current Amplifier.
Joan Yater 1 , Jonathan Shaw 1 , Kevin Jensen 1 , Tatyana Feygelson 2 , Robert Myers 3 , Bradford Pate 4 , James Butler 4
1 Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC, District of Columbia, United States, 2 , SAIC, Washington, District of Columbia, United States, 3 , Beam-Wave Research, Inc., Bethesda, Maryland, United States, 4 Chemistry Division, Naval Research Laboratory, Washington, DC, District of Columbia, United States
Show AbstractHigh-current-density cathodes are required for the development of high-power mm-wave and upper mm-wave devices, as well as for other electron beam applications. To address this need, a current amplifier stage is being developed that will multiply an incident electron current (via the secondary-electron multiplication process) and then emit the amplified beam so as to achieve a current gain of 50-100. Diamond is a particularly promising current amplification source due to the negative electron affinity present at stable hydrogenated surfaces. As such, we are fabricating current amplifiers using single-crystal CVD diamond films grown at NRL, with our growth effort focused on reducing the impurity concentration in thin freestanding CVD films and on preparing defect-free, atomically-smooth emission surfaces. While we have demonstrated transmission gains with an unbiased 8-micron-thick diamond film, we are striving to increase the gain by increasing the transport efficiency in a biased amplifier structure. The fabrication approach for achieving such biased amplifiers will be described, along with our progress in the growth, bonding, and metallization efforts. In addition, emission measurements and electrical characterization data will be presented from our initial biased amplifiers.
4:45 PM - A13.2
Ultralow Workfunction Surfaces Based on Diamondoid Monolayers.
Karthik Narasimha 1 2 , Chenhao Ge 1 2 , Jason Fabbri 1 2 , William Clay 2 , Peter Schreiner 3 , Jeremy Dahl 2 , Zhi-Xun Shen 2 , Nick Melosh 1 2
1 Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States, 3 Department of Chemistry, Justus-Liebig University of Giessen, Giessen Germany
Show AbstractDiamondoids are molecular fragments of diamond that combine the facile processing of small molecules together with the unique properties of diamond. Higher diamondoids (~1-2nm) define an important size scale in which interesting property transitions are expected from lower diamondoids (<1nm) and CVD grown nano-crystalline diamond (2nm-mm). Since CVD-diamond is a good field emitter, we performed field emission measurements on diamondoid coated gold nanowires surfaces. Diamondoid-coated nanowires consistently had dramatically lower workfunctions (~1.88 eV) than gold alone (~4.8eV) for several different diamondoid types. This effect was not observed for alkanes, which are similar sp3-hybridized carbon molecules. We hypothesize that this arises due to formation of a stable diamondoid radical cation, which could lead to a new class of tunable low-workfunction surface coatings based on chemically modified diamondoids.
5:00 PM - A13.3
Electron Emission from Diamond and the Diamond Amplified Photocathode.
Erik Muller 1 , John Smedley 2 , Triveni Rao 2
1 Stony Brook University, Physics and Astronomy, Stony Brook, New York, United States, 2 Instrumentation, Brookhaven National Laboratory, Upton, New York, United States
Show AbstractThe ability of diamond to form a stable negative electron affinity (NEA) surface and support large current densities makes it an attractive material for use in the next generation high-brightness and high-average-current electron sources. Diamond can be used as a DUV/X-ray photocathode, and as an amplifier for energetic electrons produced from another photocathode. Emission results from hydrogen terminated (001) diamond will be discussed. In the case of x-ray generated secondary electrons, we have observed electron emission consistent with the expected mean ionization energy (~13 eV) from the hydrogen terminated NEA surface for electric fields greater than 1.5 MV/m. In addition, measurements on a diamond amplified photocathode will be described. Secondary electrons are generated in the diamond by primary electrons emitted from a copper photocathode which have been accelerated to 7 keV. The electrons emitted from the diamond follows the temporal structure of the laser pulse incident on the copper photocathode and a gain of ~10 is observed. Bunch spreading and the effects of charge trapping will also be discussed.
5:15 PM - A13.4
Role of Photoelectron Emission on the Response of Single Crystal Diamond Based Extreme-UV Detectors.
Maurizio Angelone 1 , Isabella Ciancaglioni 2 , Marco Marinelli 2 , Enrico Milani 2 , Mario Pillon 1 , Giuseppe Prestopino 1 , Claudio Verona 2 , Gianluca Verona Rinati 2
1 , Associazione EURATOM/ENEA, Frascati Italy, 2 , Università di Roma "Tor Vergata", Rome Italy
Show AbstractThe physical detection processes which determine the spectral responsivity of diamond based detectors in the Extreme Ultra Violet (EUV) spectral region were extensively studied. In particular, it has been observed that secondary photoelectron current have an extremely relevant role in the detection process at EUV wavelengths. To this purpose, a detailed analysis of both the internal photocurrent and the photoelectric emission current contribution was carried out. Two different structures were compared: (i) a multilayered p type/intrinsic/metal configuration with a semitransparent top electrode and (ii) interdigitated contacts. Different metals, i.e. Silver (Ag), Platinum (Pt), Aluminium (Al), Chromium (Cr) and Gold (Au), deposited by thermal evaporation, have been tested.The devices were electrically characterized by I-V and C-V measurements and tested in the EUV spectral region by using He-Ne DC gas discharge radiation sources and a toroidal grating vacuum monochromator. The external quantum efficiency (EQE) as well as the absolute responsivity have been measured in the spectral range from 20 to 150 nm. A large variation of the spectral response was observed as a function of the adopted contact metal and of the device geometry. The analysis of the data showed that secondary electron emission current from the illuminated surfaces have a deep impact on the photoresponse of the device in the 50-100 nm spectral range and can be even larger than internal photocurrent signal in such wavelengths band. This contribution, which clearly depends on the particular design of the device and on the environmental condition (e.g. external electric fields and charging effects), is less stable and reproducible than the internal photocurrent contribution, producing a worsening of the detector performance. This effect is more relevant in interdigitated geometry devices than in multilayered structure detectors. Moreover, in the latter ones, the contribution of secondary electron emission to the device response can be completely removed by a proper design of the device housing.
5:30 PM - A13.5
Quadrant Detectors for Time-resolved Beam Position Monitoring.
John Smedley 1 , Klaus Attenkofer 2 , Erik Muller 3 , Gianluigi De Geronimo 1 , Jack Fried 1
1 Instrumentation, Brookhaven National Laboratory, Upton, New York, United States, 2 , Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States, 3 Physics and Astronomy, Stony Brook University, Stony Brook, New York, United States
Show AbstractModern Synchrotrons are capable of significant per-pulse x-ray flux, and time resolved pulse-probe experiments have become feasible. These experiments provide unique demands on x-ray monitors, as the beam position, flux and arrival time all potentially need to be recorded for each x-ray pulse. This information must be extracted at a repetition rate of up to several MHz. We report on a diamond quadrant monitor demonstrated at the Advanced Photon Source (APS) at Argonne National Laboratory. The monitor has a position resolution of better than 100 nm for a stable beam, is linear in flux over a wide dynamic range, and can resolve beam motion shot-by-shot in the APS 24-bunch operational mode (6.5 MHz). This device has been used to monitor both the short term and long term stability of the beam. Custom application-specific integrated circuits have been used to provide real-time read-out of this device.