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1

Nitrogen-incorporated ultrananocrystalline diamond and multi-layer-graphene-like hybrid carbon films  

PubMed Central

Nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) and multi-layer-graphene-like hybrid carbon films have been synthesized by microwave plasma enhanced chemical vapor deposition (MPECVD) on oxidized silicon which is pre-seeded with diamond nanoparticles. MPECVD of N-UNCD on nanodiamond seeds produces a base layer, from which carbon structures nucleate and grow perpendicularly to form standing carbon platelets. High-resolution transmission electron microscopy and Raman scattering measurements reveal that these carbon platelets are comprised of ultrananocrystalline diamond embedded in multilayer-graphene-like carbon structures. The hybrid carbon films are of low electrical resistivity. UNCD grains in the N-UNCD base layer and the hybrid carbon platelets serve as high-density diamond nuclei for the deposition of an electrically insulating UNCD film on it. Biocompatible carbon-based heaters made of low-resistivity hybrid carbon heaters encapsulated by insulating UNCD for possible electrosurgical applications have been demonstrated. PMID:24681781

Tzeng, Yonhua; Yeh, Shoupu; Fang, Wei Cheng; Chu, Yuehchieh

2014-01-01

2

Nitrogen-incorporated ultrananocrystalline diamond and multi-layer-graphene-like hybrid carbon films  

NASA Astrophysics Data System (ADS)

Nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) and multi-layer-graphene-like hybrid carbon films have been synthesized by microwave plasma enhanced chemical vapor deposition (MPECVD) on oxidized silicon which is pre-seeded with diamond nanoparticles. MPECVD of N-UNCD on nanodiamond seeds produces a base layer, from which carbon structures nucleate and grow perpendicularly to form standing carbon platelets. High-resolution transmission electron microscopy and Raman scattering measurements reveal that these carbon platelets are comprised of ultrananocrystalline diamond embedded in multilayer-graphene-like carbon structures. The hybrid carbon films are of low electrical resistivity. UNCD grains in the N-UNCD base layer and the hybrid carbon platelets serve as high-density diamond nuclei for the deposition of an electrically insulating UNCD film on it. Biocompatible carbon-based heaters made of low-resistivity hybrid carbon heaters encapsulated by insulating UNCD for possible electrosurgical applications have been demonstrated.

Tzeng, Yonhua; Yeh, Shoupu; Fang, Wei Cheng; Chu, Yuehchieh

2014-03-01

3

Systematic studies of the nucleation and growth of ultrananocrystalline diamond films on silicon substrates coated with a tungsten layer  

SciTech Connect

We report on effects of a tungsten layer deposited on silicon surface on the effectiveness for diamond nanoparticles to be seeded for the deposition of ultrananocrystalline diamond (UNCD). Rough tungsten surface and electrostatic forces between nanodiamond seeds and the tungsten surface layer help to improve the adhesion of nanodiamond seeds on the tungsten surface. The seeding density on tungsten coated silicon thus increases. Tungsten carbide is formed by reactions of the tungsten layer with carbon containing plasma species. It provides favorable (001) crystal planes for the nucleation of (111) crystal planes by Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) in argon diluted methane plasma and further improves the density of diamond seeds/nuclei. UNCD films grown at different gas pressures on tungsten coated silicon which is pre-seeded by nanodiamond along with heteroepitaxially nucleated diamond nuclei were characterized by Raman scattering, field emission-scanning electron microscopy, and high resolution-transmission electron microscopy.

Chu, Yueh-Chieh; Jiang, Gerald [Institute of Microelectronics, No.1, University Road, Tainan 701, Taiwan (China); Tu, Chia-Hao [Institute of Nanotechnology and Microsystems Engineering, No.1, University Road, Tainan 701, Taiwan (China); Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan (China); Chang Chi [Institute of Nanotechnology and Microsystems Engineering, No.1, University Road, Tainan 701, Taiwan (China); Liu, Chuan-pu; Ting, Jyh-Ming [Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan (China); Lee, Hsin-Li [Industrial Technology Research Institute - South, Tainan 701, Taiwan (China); Tzeng, Yonhua [Institute of Microelectronics, No.1, University Road, Tainan 701, Taiwan (China); Advanced Optoelectronics Technology Center, No.1, University Road, Tainan 701, Taiwan (China); Auciello, Orlando [Argonne National Laboratory, Materials Science Division, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States)

2012-06-15

4

Systematic studies of the nucleation and growth of ultrananocrystalline diamond films on silicon substrates coated with a tungsten layer  

NASA Astrophysics Data System (ADS)

We report on effects of a tungsten layer deposited on silicon surface on the effectiveness for diamond nanoparticles to be seeded for the deposition of ultrananocrystalline diamond (UNCD). Rough tungsten surface and electrostatic forces between nanodiamond seeds and the tungsten surface layer help to improve the adhesion of nanodiamond seeds on the tungsten surface. The seeding density on tungsten coated silicon thus increases. Tungsten carbide is formed by reactions of the tungsten layer with carbon containing plasma species. It provides favorable (001) crystal planes for the nucleation of (111) crystal planes by Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) in argon diluted methane plasma and further improves the density of diamond seeds/nuclei. UNCD films grown at different gas pressures on tungsten coated silicon which is pre-seeded by nanodiamond along with heteroepitaxially nucleated diamond nuclei were characterized by Raman scattering, field emission-scanning electron microscopy, and high resolution-transmission electron microscopy.

Chu, Yueh-Chieh; Tu, Chia-Hao; Jiang, Gerald; Chang, Chi; Liu, Chuan-pu; Ting, Jyh-Ming; Lee, Hsin-Li; Tzeng, Yonhua; Auciello, Orlando

2012-06-01

5

Electrical contacts to ultrananocrystalline diamond  

NASA Astrophysics Data System (ADS)

The contact behavior of various metals on n-type nitrogen-doped ultrananocrystalline diamond (UNCD) thin films has been investigated. The influences of the following parameters on the current-voltage characteristics of the contacts are presented: (1) electronegativity and work function of various metals, (2) an oxidizing acid surface cleaning step, and (3) oxide formation at the film/contact interface. Near-ideal ohmic contacts are formed in every case, while Schottky barrier contacts prove more elusive. These results counter most work discussed to date on thin diamond films, and are discussed in the context of the unique grain-boundary conductivity mechanism of the nitrogen-doped UNCD.

Gerbi, J. E.; Auciello, O.; Birrell, J.; Gruen, D. M.; Alphenaar, B. W.; Carlisle, J. A.

2003-09-01

6

Electronic Properties and Applications of Ultrananocrystalline Diamond  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) is a 3?5 nm grain size material with many of the properties of diamond. Whilst intrinsic UNCD films display a mildp-type characteristic with high resistivity, the addition of nitrogen to the gas phase during deposition renders the material n-type with low resistivity and activation energy. Hall effect measurements as a function of temperature show that this conductivity

O. A. Williams; T. Zimmermann; M. Kubovic; A. Denisenko; E. Kohn; R. B. Jackman; D. M. Gruen

7

Nanopatterning of ultrananocrystalline diamond thin films via block copolymer lithography  

Microsoft Academic Search

Nanopatterning of diamond surfaces is critical for the development of diamond-based microelectromechanical system\\/nanoelectromechanical system (MEMS\\/NEMS), such as resonators or switches. Micro-\\/nanopatterning of diamond materials is typically done using photolithography or electron beam lithography combined with reactive ion etching (RIE). In this work, we demonstrate a simple process, block copolymer (BCP) lithography, for nanopatterning of ultrananocrystalline diamond (UNCD) films to produce

Muruganathan Ramanathan; Seth B. Darling; Anirudha V. Sumant; Orlando Auciello

2010-01-01

8

Nanopatterning of ultrananocrystalline diamond thin films via block copolymer lithography.  

SciTech Connect

Nanopatterning of diamond surfaces is critical for the development of diamond-based microelectromechanical system/nanoelectromechanical system (MEMS/NEMS), such as resonators or switches. Micro-/nanopatterning of diamond materials is typically done using photolithography or electron beam lithography combined with reactive ion etching (RIE). In this work, we demonstrate a simple process, block copolymer (BCP) lithography, for nanopatterning of ultrananocrystalline diamond (UNCD) films to produce nanostructures suitable for the fabrication of NEMS based on UNCD. In BCP lithography, nanoscale self-assembled polymeric domains serve as an etch mask for pattern transfer. The authors used thin films of a cylinder-forming organic-inorganic BCP, poly(styrene-block-ferrocenyldimethylsilane), PS-b-PFS, as an etch mask on the surface of UNCD films. Orientational control of the etch masking cylindrical PFS blocks is achieved by manipulating the polymer film thickness in concert with the annealing treatment. We have observed that the surface roughness of UNCD layers plays an important role in transferring the pattern. Oxygen RIE was used to etch the exposed areas of the UNCD film underneath the BCP. Arrays of both UNCD posts and wirelike structures have been created using the same starting polymeric materials as the etch mask.

Ramanathan, M.; Darling, S. B.; Sumant, A. V.; Auciello, O.

2010-07-01

9

Ultrananocrystalline diamond-decorated silicon nanowire field emitters.  

PubMed

Silicon nanowires (SiNWs) were uniformly decorated with ultrananocrystalline diamond (UNCD) by a novel route using paraffin wax as the seeding source, which is more efficient in the creation of diamond nuclei than traditional methods. These one-dimensional ultrananocrystalline diamond-decorated SiNWs (UNCD/SiNWs) exhibit uniform diameters ranging from 100 to 200 nm with a bulbous catalytic tip of ?250 nm in diameter and an UNCD grain size of ?5 nm. UNCD/SiNW nanostructures demonstrated enhanced electron field emission (EFE) properties with a turn-on field of about 3.7 V/?m. Current densities around 2 mA/cm(2) were achieved at 25 V/?m, which is significantly enhanced as compared to bare SiNWs. PMID:25046006

Palomino, Javier; Varshney, Deepak; Resto, Oscar; Weiner, Brad R; Morell, Gerardo

2014-08-27

10

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods  

PubMed Central

Vertically aligned conducting ultrananocrystalline diamond (UNCD) nanorods are fabricated using the reactive ion etching method incorporated with nanodiamond particles as mask. High electrical conductivity of 275??·cm?1 is obtained for UNCD nanorods. The microplasma cavities using UNCD nanorods as cathode show enhanced plasma illumination characteristics of low threshold field of 0.21?V/?m with plasma current density of 7.06?mA/cm2 at an applied field of 0.35?V/?m. Such superior electrical properties of UNCD nanorods with high aspect ratio potentially make a significant impact on the diamond-based microplasma display technology. PMID:23009733

2012-01-01

11

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods.  

PubMed

Vertically aligned conducting ultrananocrystalline diamond (UNCD) nanorods are fabricated using the reactive ion etching method incorporated with nanodiamond particles as mask. High electrical conductivity of 275??·cm-1 is obtained for UNCD nanorods. The microplasma cavities using UNCD nanorods as cathode show enhanced plasma illumination characteristics of low threshold field of 0.21?V/?m with plasma current density of 7.06?mA/cm2 at an applied field of 0.35?V/?m. Such superior electrical properties of UNCD nanorods with high aspect ratio potentially make a significant impact on the diamond-based microplasma display technology. PMID:23009733

Sankaran, Kamatchi Jothiramalingam; Kunuku, Srinivasu; Lou, Shiu-Cheng; Kurian, Joji; Chen, Huang-Chin; Lee, Chi-Young; Tai, Nyan-Hwa; Leou, Keh-Chyang; Chen, Chulung; Lin, I-Nan

2012-01-01

12

Characterization of ultrananocrystalline diamond microsensors for in vivo dopamine detection.  

PubMed

We show the technical feasibility of coating and micro patterning boron-doped ultrananocrystalline diamond (UNCD(®)) on metal microwires and of applying them as microsensors for the detection of dopamine in vivo using fast-scan cyclic voltammetry. UNCD electrode surface consistently generated electrochemical signals with high signal-to-noise ratio of >800 using potassium ferrocyanide-ferricyanide redox couple. Parylene patterned UNCD microelectrodes were effectively applied to detect dopamine reliably in vitro using flow injection analysis with a detection limit of 27?nM and in the striatum of the anesthetized rat during electrical stimulation of dopamine neurons. PMID:23918991

Arumugam, Prabhu U; Zeng, Hongjun; Siddiqui, Shabnam; Covey, Dan P; Carlisle, John A; Garris, Paul A

2013-06-24

13

Characterization of ultrananocrystalline diamond microsensors for in vivo dopamine detection  

NASA Astrophysics Data System (ADS)

We show the technical feasibility of coating and micro patterning boron-doped ultrananocrystalline diamond (UNCD®) on metal microwires and of applying them as microsensors for the detection of dopamine in vivo using fast-scan cyclic voltammetry. UNCD electrode surface consistently generated electrochemical signals with high signal-to-noise ratio of >800 using potassium ferrocyanide-ferricyanide redox couple. Parylene patterned UNCD microelectrodes were effectively applied to detect dopamine reliably in vitro using flow injection analysis with a detection limit of 27 nM and in the striatum of the anesthetized rat during electrical stimulation of dopamine neurons.

Arumugam, Prabhu U.; Zeng, Hongjun; Siddiqui, Shabnam; Covey, Dan P.; Carlisle, John A.; Garris, Paul A.

2013-06-01

14

Characterization of ultrananocrystalline diamond microsensors for in vivo dopamine detection  

PubMed Central

We show the technical feasibility of coating and micro patterning boron-doped ultrananocrystalline diamond (UNCD®) on metal microwires and of applying them as microsensors for the detection of dopamine in vivo using fast-scan cyclic voltammetry. UNCD electrode surface consistently generated electrochemical signals with high signal-to-noise ratio of >800 using potassium ferrocyanide-ferricyanide redox couple. Parylene patterned UNCD microelectrodes were effectively applied to detect dopamine reliably in vitro using flow injection analysis with a detection limit of 27?nM and in the striatum of the anesthetized rat during electrical stimulation of dopamine neurons. PMID:23918991

Arumugam, Prabhu U.; Zeng, Hongjun; Siddiqui, Shabnam; Covey, Dan P.; Carlisle, John A.; Garris, Paul A.

2013-01-01

15

Charging characteritiscs of ultrananocrystalline diamond in RF MEMS capacitive switches.  

SciTech Connect

Modifications to a standard capacitive MEMS switch process have been made to allow the incorporation of ultra-nano-crystalline diamond as the switch dielectric. The impact on electromechanical performance is minimal. However, these devices exhibit uniquely different charging characteristics, with charging and discharging time constants 5-6 orders of magnitude quicker than conventional materials. This operation opens the possibility of devices which have no adverse effects of dielectric charging and can be operated near-continuously in the actuated state without significant degradation in reliability.

Sumant, A. V.; Goldsmith, C.; Auciello, O.; Carlisle, J.; Zheng, H.; Hwang, J. C. M.; Palego, C.; Wang, W.; Carpick, R.; Adiga, V.; Datta, A.; Gudeman, C.; O'Brien, S.; Sampath, S.

2010-05-01

16

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous  

E-print Network

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond report the mechanical properties of three emerging materials in thin film form: single crystal silicon carbide 3C-SiC , ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon

Espinosa, Horacio D.

17

Mechanical stiffness and dissipation in ultrananocrystalline diamond micro-resonators.  

SciTech Connect

We have characterized mechanical properties of ultrananocrystalline diamond (UNCD) thin films grown using the hot filament chemical vapor deposition (HFCVD) technique at 680 C, significantly lower than the conventional growth temperature of {approx}800 C. The films have {approx}4.3% sp{sup 2} content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, {approx}1 {micro}m thick, exhibit a net residual compressive stress of 370 {+-} 1 MPa averaged over the entire 150 mm wafer. UNCD microcantilever resonator structures and overhanging ledges were fabricated using lithography, dry etching, and wet release techniques. Overhanging ledges of the films released from the substrate exhibited periodic undulations due to stress relaxation. This was used to determine a biaxial modulus of 838 {+-} 2 GPa. Resonant excitation and ring-down measurements in the kHz frequency range of the microcantilevers were conducted under ultrahigh vacuum (UHV) conditions in a customized UHV atomic force microscope system to determine Young's modulus as well as mechanical dissipation of cantilever structures at room temperature. Young's modulus is found to be 790 {+-} 30 GPa. Based on these measurements, Poisson's ratio is estimated to be 0.057 {+-} 0.038. The quality factors (Q) of these resonators ranged from 5000 to 16000. These Q values are lower than theoretically expected from the intrinsic properties of diamond. The results indicate that surface and bulk defects are the main contributors to the observed dissipation in UNCD resonators.

Sumant, A. V.; Adiga, V. P.; Suresh, S.; Gudeman, C.; Auciello, O.; Carlis, J. A.; Carpick, R. W.

2009-01-01

18

Two- and three-dimensional ultrananocrystalline diamond (UNCD) structures for a high resolution diamond-based MEMS technology.  

SciTech Connect

Silicon is currently the most commonly used material for the fabrication of microelectromechanical systems (MEMS). However, silicon-based MEMS will not be suitable for long-endurance devices involving components rotating at high speed, where friction and wear need to be minimized, components such as 2-D cantilevers that may be subjected to very large flexural displacements, where stiction is a problem, or components that will be exposed to corrosive environments. The mechanical, thermal, chemical, and tribological properties of diamond make it an ideal material for the fabrication of long-endurance MEMS components. Cost-effective fabrication of these components could in principle be achieved by coating Si with diamond films and using conventional lithographic patterning methods in conjunction with e. g. sacrificial Ti or SiO{sub 2} layers. However, diamond coatings grown by conventional chemical vapor deposition (CVD) methods exhibit a coarse-grained structure that prevents high-resolution patterning, or a fine-grained microstructure with a significant amount of intergranular non-diamond carbon. The authors demonstrate here the fabrication of 2-D and 3-D phase-pure ultrananocrystalline diamond (UNCD) MEMS components by coating Si with UNCD films, coupled with lithographic patterning methods involving sacrificial release layers. UNCD films are grown by microwave plasma CVD using C{sub 60}-Ar or CH{sub 4}-Ar gas mixtures, which result in films that have 3--5 nm grain size, are 10--20 times smoother than conventionally grown diamond films, are extremely resistant to corrosive environments, and are predicted to have a brittle fracture strength similar to that of single crystal diamond.

Auciello, O.; Krauss, A. R.; Gruen, D. M.; Busmann, H. G.; Meyer, E. M.; Tucek, J.; Sumant, A.; Jayatissa, A.; Moldovan, N.; Mancini, D. C.; Gardos, M. N.

2000-01-17

19

Ultrananocrystalline diamond tip integrated onto a heated atomic force microscope cantilever This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Ultrananocrystalline diamond tip integrated onto a heated atomic force microscope cantilever.1088/0957-4484/23/49/495302 Ultrananocrystalline diamond tip integrated onto a heated atomic force microscope cantilever Hoe Joon Kim1, Nicolaie Urbana-Champaign, Urbana, IL 61801, USA 2 Advanced Diamond Technologies Inc., Romeoville, IL 60446, USA 3

King, William P.

20

Ultrathin ultrananocrystalline diamond film synthesis by direct current plasma-assisted chemical vapor deposition  

Microsoft Academic Search

The synthesis of ultrathin, mirror-smooth, and void-free ultra-nanocrystalline diamond (UNCD) film was investigated using DC-PACVD. The seeding process was investigated in the previously reported “two-step” seeding scheme, where the substrate was pretreated in microwave hydrocarbon plasma prior to the ultrasonic seeding to enhance seed density; in the present study, DC plasma and hot filament process were adopted for the pretreatment,

Hak-Joo Lee; Hyeongtag Jeon; Wook-Seong Lee

2011-01-01

21

Investigation of the initial growth of ultrananocrystalline diamond films by multiwavelength Raman spectroscopy  

Microsoft Academic Search

The initial growth phase of ultrananocrystalline diamond\\/amorphous carbon nanocomposite films (UNCD\\/a-C) has been investigated by scanning electron microscopy, atomic force microscopy and especially Raman spectroscopy. As due to resonance effects Raman spectra of carbon materials strongly depend on the excitation wavelength, a multiwavelength analysis has been performed with ?exc ranging from the UV region (325nm) over the visible range (488

W. Kulisch; C. Popov; H. Rauscher; M. Rinke; M. Veres

2011-01-01

22

Engineering the interface characteristics of ultrananocrystalline diamond films grown on Au-coated Si substrates.  

PubMed

Enhanced electron field emission (EFE) properties have been observed for ultrananocrystalline diamond (UNCD) films grown on Au-coated Si (UNCD/Au-Si) substrates. The EFE properties of UNCD/Au-Si could be turned on at a low field of 8.9 V/?m, attaining EFE current density of 4.5 mA/cm(2) at an applied field of 10.5 V/?m, which is superior to that of UNCD films grown on Si (UNCD/Si) substrates with the same chemical vapor deposition process. Moreover, a significant difference in current-voltage curves from scanning tunneling spectroscopic measurements at the grain and the grain boundary has been observed. From the variation of normalized conductance (dI/dV)/(I/V) versus V, bandgap of UNCD/Au-Si is measured to be 2.8 eV at the grain and nearly metallic at the grain boundary. Current imaging tunneling spectroscopy measurements show that the grain boundaries have higher electron field emission capacity than the grains. The diffusion of Au into the interface layer that results in the induction of graphite and converts the metal-to-Si interface from Schottky to Ohmic contact is believed to be the authentic factors, resulting in marvelous EFE properties of UNCD/Au-Si. PMID:22823911

Sankaran, Kamatchi Jothiramalingam; Panda, Kalpataru; Sundaravel, Balakrishnan; Chen, Huang-Chin; Lin, I-Nan; Lee, Chi-Young; Tai, Nyan-Hwa

2012-08-01

23

Low temperature growth of ultrananocrystalline diamond on glass substrates for field emission applications.  

SciTech Connect

Recent studies of field emission from diamond have focused on the feasibility of growing diamond films on glass substrates, which are the preferred choice for cost-effective, large area flat panel displays. However, diamond growth on glass requires temperatures {le} 500 C, which is much lower than the temperature needed for growing conventional microwave plasma chemical vapor deposition (CVD) diamond films. In addition, it is desirable to minimize the deposition time for cost-effective processing. The authors have grown ultrananocrystalline diamond (UNCD) films using a unique microwave plasma technique that involves CH{sub 4}-Ar gas mixtures, as opposed to the conventional CH{sub 4}-H{sub 2} plasma CVD method. The growth species in the CH{sub 4}-Ar CVD method are C{sub 2} dimers, resulting in lower activation energies and consequently the ability to grow diamond at lower temperatures than conventional CVD diamond processes. For the work discussed here, the UNCD films were grown with plasma-enhanced chemical vapor deposition (PECVD) at low temperatures on glass substrates coated with Ti thin films. The turn-on field was as low as 3 V/{mu}m for a film grown at 500 C with a gas chemistry of 1%CH{sub 4}/99%/Ar at 100 Torr, and 7 V/{mu}m for a film grown at 350 C. UV Raman spectroscopy revealed the presence of high quality diamond in the films.

Corrigan, T. D.; Krauss, A. R.; Gruen, D. M.; Auciello, O.; Chang, R. P. H.

2000-01-17

24

Ultrananocrystalline and nanocrystalline diamond thin films for NEMS/MEMS applications.  

SciTech Connect

There has been a tireless quest by the designers of micro- and nanoelectro mechanical systems (MEMS/NEMS) to find a suitable material alternative to conventional silicon. This is needed to develop robust, reliable, and long-endurance MEMS/NEMS with capabilities for working under demanding conditions, including harsh environments, high stresses, or with contacting and sliding surfaces. Diamond is one of the most promising candidates for this because of its superior physical, chemical, and tribomechanical properties. Ultrananocrystalline diamond (UNCD) and nanocrystalline diamond (NCD) thin films, the two most studied forms of diamond films in the last decade, have distinct growth processes and nanostructures but complementary properties. This article reviews the fundamental and applied science performed to understand key aspects of UNCD and NCD films, including the nucleation and growth, tribomechanical properties, electronic properties, and applied studies on integration with piezoelectric materials and CMOS technology. Several emerging diamond-based MEMS/NEMS applications, including high-frequency resonators, radio frequency MEMS and photonic switches, and the first commercial diamond MEMS product - monolithic diamond atomic force microscopy probes - are discussed.

Sumant, A. V.; Auciello, O.; Carpick, R. W.; Srinivasan, S.; Butler, J. E. (Center for Nanoscale Materials); ( MSD); ( PSC-USR)

2010-04-01

25

Low-temperature electrical transport in B-doped ultrananocrystalline diamond film  

SciTech Connect

B-doped ultrananocrystalline diamond (UNCD) films are grown using hot-filament chemical vapor deposition method, and their electrical transport properties varying with temperature are investigated. When the B-doped concentration of UNCD film is low, a step-like increase feature of the resistance is observed with decreasing temperature, reflecting at least three temperature-modified electronic state densities at the Fermi level according to three-dimensional Mott's variable range hopping transport mechanism, which is very different from that of reported B-doped nanodiamond. With increasing B-doped concentration, a superconductive transformation occurs in the UNCD film and the highest transformation temperature of 5.3?K is observed, which is higher than that reported for superconducting nanodiamond films. In addition, the superconducting coherence length is about 0.63?nm, which breaks a reported theoretical and experimental prediction about ultra-nanoscale diamond's superconductivity.

Li, Lin; Zhao, Jing; Hu, Zhaosheng; Quan, Baogang; Li, Junjie, E-mail: jjli@iphy.ac.cn; Gu, Changzhi, E-mail: czgu@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institution of Physics Chinese Academy of Sciences, Beijing 100190 (China)

2014-05-05

26

Flexible electron field emitters fabricated using conducting ultrananocrystalline diamond pyramidal microtips on polynorbornene films  

SciTech Connect

High performance flexible field emitters made of aligned pyramidal shaped conducting ultrananocrystalline diamond (C-UNCD) microtips on polynorbornene substrates is demonstrated. Flexible C-UNCD pyramidal microtips show a low turn-on field of 1.80?V/?m with a field enhancement factor of 4580 and a high emission current density of 5.8?mA/cm{sup 2} (at an applied field of 4.20?V/?m) with life-time stability of 210 min. Such an enhancement in the field emission is due to the presence of sp{sup 2}-graphitic sheath with a nanowire-like diamond core. This high performance flexible C-UNCD field emitter is potentially useful for the fabrication of diverse, flexible electronic devices.

Sankaran, K. J.; Tai, N. H., E-mail: nhtai@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Lin, I. N., E-mail: inanlin@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

2014-01-20

27

Characterization of nitrogen-incorporated ultrananocrystalline diamond as a robust cold cathode material  

NASA Astrophysics Data System (ADS)

Carbon materials, including carbon nanotubes and nanostructured diamond, have been investigated for over a decade for application to electron field emission devices. In particular, they have been investigated because of their low power consumption, potential for miniaturization, and robustness as field emission materials, all properties that make nanocarbon materials strong candidates for applications as long life electron sources for mass spectrometers for space exploration, where electron sources are exposed to harsh environments, .A miniaturized mass spectrometer under development for in situ chemical analysis on the moon and other planetary environments requires a robust, long-lived electron source, to generate ions from gaseous sample using electron impact ionization. To this end, we have explored the field emission properties and lifetime of nitrogen-incorporated ultrananocrystalline diamond films. We will present recent results revealing that UNCD films with nitrogen incorporation during growth (N-UNCD) yield stable/high fieldinduced electron emission in high vacuum for up to 1000 hours.

Getty, Stephanie A.; Auciello, Orlando; Sumant, Anirudha V.; Wang, Xinpeng; Glavin, Daniel P.; Mahaffy, Paul R.

2010-04-01

28

Science and technology of ultrananocrystalline diamond (UNCD) thin films for multifunctional devices.  

SciTech Connect

MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties, and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors, However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophyllic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments. Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS-MMAS) is 10,000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS-MMA applications. A thin film deposition process has been developed that produces phase-pure ultrananocrystalline diamond (UNCD) with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. We have developed lithographic techniques for the fabrication of diamond microstructure including cantilevers and multi-level devices, acting as precursors to micro-bearings and gears, making UNCD a promising material for the development of high performance MEMS devices.

Auciello, O.; Gruen, D. M.; Krauss, A. R.; Jayatissa, A.; Sumant, A.; Tucek, J.; Mancini, D.; Moldovan, N.; Erdemir, A.; Ersoy, D.; Gardos, M. N.; Busmann, H. G.; Meyer, E. M.

2000-11-15

29

Improvement in tribological properties by modification of grain boundary and microstructure of ultrananocrystalline diamond films.  

PubMed

Grain boundaries and microstructures of ultrananocrystalline diamond (UNCD) films are engineered at nanoscale by controlling the substrate temperature (TS) and/or by introducing H2 in the commonly used Ar/CH4 deposition plasma in a microwave plasma enhanced chemical vapor deposition system. A model for the grain growth is proposed. The films deposited at low TS consist of random/spherical shaped UNCD grains with well-defined grain boundaries. On increasing TS, the adhering efficiency of CH radical onto diamond lattice drops and trans-polyacetylene (t-PA) encapsulating the nanosize diamond clusters break due to hydrogen abstraction activated, rendering the diamond phase less passivated. This leads to the C2 radical further attaching to the diamond lattice, resulting in the modification of grain boundaries and promoting larger sized clustered grains with a complicated defect structure. Introduction of H2 in the plasma at low TS gives rise to elongated clustered grains that is attributed to the presence of atomic hydrogen in the plasma, preferentially etching out the t-PA attached to nanosized diamond clusters. On the basis of this model a technologically important functional property, namely tribology of UNCD films, is studied. A low friction of 0.015 is measured for the film when ultranano grains are formed, which consist of large fractions of grain boundary components of sp(2)/a-C and t-PA phases. The grain boundary component consists of large amounts of hydroxylic and carboxylic functional groups which passivates the covalent carbon dangling bonds, hence low friction coefficient. The improved tribological properties of films can make it a promising candidate for various applications, mainly in micro/nanoelectro mechanical system (M/NEMS), where low friction is required for high efficiency operation of devices. PMID:23581966

Sankaran, Kamatchi Jothiramalingam; Kumar, Niranjan; Kurian, Joji; Ramadoss, Radhika; Chen, Huang-Chin; Dash, Sitaram; Tyagi, Ashok Kumar; Lee, Chi-Young; Tai, Nyan-Hwa; Lin, I-Nan

2013-05-01

30

Nitrogen incorporated ultrananocrystalline diamond based field emitter array for a flat-panel x-ray source  

SciTech Connect

A field emission based flat-panel transmission x-ray source is being developed as an alternative for medical and industrial imaging. A field emitter array (FEA) prototype based on nitrogen incorporated ultrananocrystalline diamond film has been fabricated to be used as the electron source of this flat panel x-ray source. The FEA prototype was developed using conventional microfabrication techniques. The field emission characteristics of the FEA prototype were evaluated. Results indicated that emission current densities of the order of 6?mA/cm{sup 2} could be obtained at electric fields as low as 10?V/?m to 20?V/?m. During the prototype microfabrication process, issues such as delamination of the extraction gate and poor etching of the SiO{sub 2} insulating layer located between the emitters and the extraction layer were encountered. Consequently, alternative FEA designs were investigated. Experimental and simulation data from the first FEA prototype were compared and the results were used to evaluate the performance of alternative single and double gate designs that would yield better field emission characteristics compared to the first FEA prototype. The best simulation results are obtained for the double gate FEA design, when the diameter of the collimator gate is around 2.6 times the diameter of the extraction gate.

Posada, Chrystian M.; Grant, Edwin J.; Lee, Hyoung K.; Castaño, Carlos H., E-mail: castanoc@mst.edu [Nuclear Engineering, Missouri University of Science and Technology, 220 Fulton Hall, Rolla, Missouri 65401 (United States); Divan, Ralu; Sumant, Anirudha V.; Rosenmann, Daniel; Stan, Liliana [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2014-04-07

31

Cell adhesion and growth on ultrananocrystalline diamond and diamond-like carbon films after different surface modifications  

NASA Astrophysics Data System (ADS)

Diamond and diamond-like carbon (DLC) films possess a set of excellent physical and chemical properties which together with a high biocompatibility make them attractive candidates for a number of medical and biotechnological applications. In the current work thin ultrananocrystalline diamond (UNCD) and DLC films were comparatively investigated with respect to cell attachment and proliferation after different surface modifications. The UNCD films were prepared by microwave plasma enhanced chemical vapor deposition, the DLC films by pulsed laser deposition (PLD). The films were comprehensively characterized with respect to their basic properties, e.g. crystallinity, morphology, chemical bonding nature, etc. Afterwards the UNCD and DLC films were modified applying O2 or NH3/N2 plasmas and UV/O3 treatments to alter their surface termination. The surface composition of as-grown and modified samples was studied by X-ray photoelectron spectroscopy (XPS). Furthermore the films were characterized by contact angle measurements with water, formamide, 1-decanol and diiodomethane; from the results obtained the surface energy with its dispersive and polar components was calculated. The adhesion and proliferation of MG63 osteosarcoma cells on the different UNCD and DLC samples were assessed by measurement of the cell attachment efficiency and MTT assays. The determined cell densities were compared and correlated with the surface properties of as-deposited and modified UNCD and DLC films.

Miksovsky, J.; Voss, A.; Kozarova, R.; Kocourek, T.; Pisarik, P.; Ceccone, G.; Kulisch, W.; Jelinek, M.; Apostolova, M. D.; Reithmaier, J. P.; Popov, C.

2014-04-01

32

Formation of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films in Vacuum Using Coaxial Arc Plasma Gun  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite films were grown in vacuum using a coaxial arc plasma gun. From the X-ray diffraction measurement, the UNCD crystallite size was estimated to be 1.6 nm. This size is dramatically reduced from that (2.3 nm) of UNCD/hydrogenated amorphous carbon (a-C:H) composite films grown in a hydrogen atmosphere. The sp3/(sp3 + sp2) value, which was estimated from the X-ray photoemission spectrum, was also reduced to be 41%. A reason for it might be the reduction in the UNCD crystallite size. From the near-edge X-ray absorption fine-structure (NEXAFS) spectrum, it was found that the ?*C=C and ?*C?C bonds are preferentially formed instead of the ?*C-H bonds in the UNCD/a-C:H films. Since the extremely small UNCD crystallites (1.6 nm) correspond to the nuclei of diamond, we consider that UNCD crystallite formation should be due predominantly to nucleation. The supersaturated condition required for nucleation is expected to be realized in the deposition using the coaxial arc plasma gun.

Hanada, Kenji; Yoshida, Tomohiro; Nakagawa, You; Yoshitake, Tsuyoshi

2010-12-01

33

Temperature dependence of mechanical stiffness and dissipation in ultrananocrystalline diamond films grown by the HFCVD techinque.  

SciTech Connect

We have characterized mechanical properties of ultrananocrystalline diamond (UNCD) thin films grown using the hot filament chemical vapor deposition (HFCVD) technique at 680 C, significantly lower than the conventional growth temperature of -800 C. The films have -4.3% sp{sup 2} content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, -1 {micro}m thick, exhibit a net residual compressive stress of 370 {+-} 1 MPa averaged over the entire 150 mm wafer. UNCD microcantilever resonator structures and overhanging ledges were fabricated using lithography, dry etching, and wet release techniques. Overhanging ledges of the films released from the substrate exhibited periodic undulations due to stress relaxation. This was used to determine a biaxial modulus of 838 {+-} 2 GPa. Resonant excitation and ring-down measurements in the kHz frequency range of the microcantilevers were conducted under ultrahigh vacuum (UHV) conditions in a customized UHV atomic force microscope system to determine Young's modulus as well as mechanical dissipation of cantilever structures at room temperature. Young's modulus is found to be 790 {+-} 30 GPa. Based on these measurements, Poisson's ratio is estimated to be 0.057 {+-} 0.038. The quality factors (Q) of these resonators ranged from 5000 to 16000. These Q values are lower than theoretically expected from the intrinsic properties of diamond. The results indicate that surface and bulk defects are the main contributors to the observed dissipation in UNCD resonators.

Adiga, V. P.; Sumant, A. V.; Suresh, S.; Gudeman, C.; Auciello, O.; Carlisle, J. A.; Carpick, R. W.; Materials Science Division; Univ. of Pennsylvania; Innovative Micro Tech.; Advanced Diamond Tech.

2009-06-01

34

Model-based simulation of the responses of ultrananocrystalline diamond and nano structures  

NASA Astrophysics Data System (ADS)

Owing to their outstanding mechanical, tribological, electronic transport, chemical and biocompatibility properties, the ultrananocrystalline diamond (UNCD) films grown by the microwave plasma chemical vapor deposition method under hydrogen-poor conditions have become the subject of intense research interests over the past decade. Based on the available computational capabilities and experimental data, a combined kinetic Monte Carlo (KMC) and molecular dynamics (MD) procedure has been developed for large-scale atomistic simulation of the responses of polycrystalline UNCD films under various loading conditions. The mechanical responses of resulting UNCD film have been investigated by applying displacement-controlled loading in the MD simulation box. Recently, a systematic study is being performed to understand the combined effects of grain size, loading rate, temperature, imperfection, loading path and history on the material strengths and failure patterns of both pure and nitrogen-doped UNCD films. Furthermore, recent MD simulation results of the notch size effect on the failure mechanism of nano-scale hierarchical structures consisting of one-dimensional members arranged in parallel will also be discussed to better design MEMS devices.

Shen, Luming; Chen, Zhen

2009-07-01

35

Ultrananocrystalline diamond cantilever wide dynamic range acceleration/vibration/pressure sensor  

DOEpatents

An ultrananocrystalline diamond (UNCD) element formed in a cantilever configuration is used in a highly sensitive, ultra-small sensor for measuring acceleration, shock, vibration and static pressure over a wide dynamic range. The cantilever UNCD element may be used in combination with a single anode, with measurements made either optically or by capacitance. In another embodiment, the cantilever UNCD element is disposed between two anodes, with DC voltages applied to the two anodes. With a small AC modulated voltage applied to the UNCD cantilever element and because of the symmetry of the applied voltage and the anode-cathode gap distance in the Fowler-Nordheim equation, any change in the anode voltage ratio V1/N2 required to maintain a specified current ratio precisely matches any displacement of the UNCD cantilever element from equilibrium. By measuring changes in the anode voltage ratio required to maintain a specified current ratio, the deflection of the UNCD cantilever can be precisely determined. By appropriately modulating the voltages applied between the UNCD cantilever and the two anodes, or limit electrodes, precise independent measurements of pressure, uniaxial acceleration, vibration and shock can be made. This invention also contemplates a method for fabricating the cantilever UNCD structure for the sensor.

Krauss, Alan R. (Naperville, IL); Gruen, Dieter M. (Downers Grove, IL); Pellin, Michael J. (Naperville, IL); Auciello, Orlando (Bolingbrook, IL)

2002-07-23

36

Ultrananocrystalline Diamond Cantilever Wide Dynamic Range Acceleration/Vibration /Pressure Sensor  

DOEpatents

An ultrananocrystalline diamond (UNCD) element formed in a cantilever configuration is used in a highly sensitive, ultra-small sensor for measuring acceleration, shock, vibration and static pressure over a wide dynamic range. The cantilever UNCD element may be used in combination with a single anode, with measurements made either optically or by capacitance. In another embodiment, the cantilever UNCD element is disposed between two anodes, with DC voltages applied to the two anodes. With a small AC modulated voltage applied to the UNCD cantilever element and because of the symmetry of the applied voltage and the anode-cathode gap distance in the Fowler-Nordheim equation, any change in the anode voltage ratio V1/V2 required to maintain a specified current ratio precisely matches any displacement of the UNCD cantilever element from equilibrium. By measuring changes in the anode voltage ratio required to maintain a specified current ratio, the deflection of the UNCD cantilever can be precisely determined. By appropriately modulating the voltages applied between the UNCD cantilever and the two anodes, or limit electrodes, precise independent measurements of pressure, uniaxial acceleration, vibration and shock can be made. This invention also contemplates a method for fabricating the cantilever UNCD structure for the sensor.

Krauss, Alan R. (Naperville, IL); Gruen, Dieter M. (Downers Grove, IL); Pellin, Michael J. (Naperville, IL); Auciello, Orlando (Bolingbrook, IL)

2003-09-02

37

Growth of ultrananocrystalline diamond film by DC Arcjet plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Self-standing diamond films were grown by DC Arcjet plasma enhanced chemical vapor deposition (CVD). The feed gasses were Ar/H2/CH4, in which the flow ratio of CH4 to H2 (F/F) was varied from 5% to 20%. Two distinct morphologies were observed by scanning electron microscope (SEM), i.e. the "pineapple-like" morphology and the "cauliflower-like" morphology. It was found that the morphologies of the as-grown films are strongly dependent on the flow ratio of CH4 to H2 in the feed gasses. High resolution transmission electron microscope (HRTEM) survey results revealed that there were nanocrystalline grains within the "pineapple-like" films whilst there were ultrananocrystalline grains within "cauliflower-like" films. X-ray diffraction (XRD) results suggested that (110) crystalline plane was the dominant surface in the "cauliflower-like" films whilst (100) crystalline plane was the dominant surface in the "pineapple-like" films. Raman spectroscopy revealed that nanostructured carbon features could be observed in both types of films. Plasma diagnosis was carried out in order to understand the morphology dependent growth mechanism. It could be concluded that the film morphology was strongly influenced by the density of gas phases. The gradient of C2 radical was found to be different along the growth direction under the different growth conditions.

Chen, G. C.; Li, B.; Yan, Z. Q.; Liu, J.; Lu, F. X.; Ye, H.

2012-06-01

38

Electroplate and lift lithography for patterned micro/nanowires using ultrananocrystalline diamond (uncd) as a reusable template  

SciTech Connect

A fast, simple, scalable technique is described for the controlled, solution-based, electrochemical synthesis of patterned metallic and semiconducting nanowires from reusable, nonsacrificial, ultrananocrystalline diamond (UNCD) templates. This enables the repeated fabrication of arrays of complex patterns of nanowires, potentially made of any electrochemically depositable material. Unlike all other methods of patterning nanowires, this benchtop technique quickly mass-produces patterned nanowires whose diameters are not predefined by the template, without requiring intervening vacuum or clean room processing. This technique opens a pathway for studying nanoscale phenomena with minimal equipment, allowing the process-scale development of a new generation of nanowire-based devices.

Seley, D. B.; Dissing, D. A.; Divan, R.; Miller, C. S.; Auciello, O.; Terrell, E. A.; Shogren, T. S.; Fahrner, D.; Hamilton, J. P.; Zach, M. P.; Sumant, V. (Center for Nanoscale Materials); ( MSD); ( PSC-USR)

2011-01-01

39

Electroplate and Lift Lithography for Patterned Micro/Nanowires Using Ultrananocrystalline Diamond (UNCD) as a Reusable Template  

PubMed Central

A fast, simple, scalable technique is described for the controlled, solution-based, electrochemical synthesis of patterned metallic and semiconducting nanowires from reusable, nonsacrificial, ultrananocrystalline diamond (UNCD) templates. This enables the repeated fabrication of arrays of complex patterns of nanowires, potentially made of any electrochemically depositable material. Unlike all other methods of patterning nanowires, this benchtop technique quickly mass-produces patterned nanowires whose diameters are not predefined by the template, without requiring intervening vacuum or clean room processing. This technique opens a pathway for studying nanoscale phenomena with minimal equipment, allowing the process-scale development of a new generation of nanowire-based devices. PMID:21405103

2011-01-01

40

Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties.  

SciTech Connect

We present a comprehensive study of surface composition and nanotribology for ultrananocrystalline diamond (UNCD) surfaces, including the influence of film nucleation on these properties. We describe a methodology to characterize the underside of the films as revealed by sacrificial etching of the underlying substrate. This enables the study of the morphology and composition resulting from the nucleation and initial growth of the films, as well as the characterization of nanotribological properties which are relevant for applications including micro-/nanoelectromechanical systems. We study the surface chemistry, bonding configuration, and nanotribological properties of both the topside and the underside of the film with synchrotron-based x-ray absorption near-edge structure spectroscopy to identify the bonding state of the carbon atoms, x-ray photoelectron spectroscopy to determine the surface chemical composition, Auger electron spectroscopy to further verify the composition and bonding configuration, and quantitative atomic force microscopy to study the nanoscale topography and nanotribological properties. The films were grown on SiO{sub 2} after mechanically polishing the surface with detonation synthesized nanodiamond powder, followed by ultrasonication in a methanol solution containing additional nanodiamond powder. The sp{sup 2} fraction, morphology, and chemistry of the as-etched underside are distinct from the topside, exhibiting a higher sp{sup 2} fraction, some oxidized carbon, and a smoother morphology. The nanoscale single-asperity work of adhesion between a diamond nanotip and the as-etched UNCD underside is far lower than for a silicon-silicon interface (59.2 {+-} 2 vs 826 {+-} 186 mJ/m{sup 2}, respectively). Exposure to atomic hydrogen dramatically reduces nanoscale adhesion to 10.2 {+-} 0.4 mJ/m{sup 2}, at the level of van der Waals interactions and consistent with recent ab initio calculations. Friction is substantially reduced as well, demonstrating a direct link between the surface chemistry and nanoscale friction. The proposed mechanism, supported by the detailed surface spectroscopic analysis, is the elimination of reactive (e.g., C*-), polar (e.g., C-O), and {pi}-bonded (C-C) surface groups, which are replaced by fully saturated, hydrogen-terminated surface bonds to produce an inert surface that interacts minimally with the contacting counterface.

Sumant, A. V.; Grierson, D. S.; Gerbi, J. E.; Carlisle, J. A.; Auciello, O.; Carpick, R. W.; Univ. of Wisconsin at Madison

2007-12-01

41

Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties  

SciTech Connect

We present a comprehensive study of surface composition and nanotribology for ultrananocrystalline diamond (UNCD) surfaces, including the influence of film nucleation on these properties. We describe a methodology to characterize the underside of the films as revealed by sacrificial etching of the underlying substrate. This enables the study of the morphology and composition resulting from the nucleation and initial growth of the films, as well as the characterization of nanotribological properties which are relevant for applications including micro-/nanoelectromechanical systems. We study the surface chemistry, bonding configuration, and nanotribological properties of both the topside and the underside of the film with synchrotron-based x-ray absorption near-edge structure spectroscopy to identify the bonding state of the carbon atoms, x-ray photoelectron spectroscopy to determine the surface chemical composition, Auger electron spectroscopy to further verify the composition and bonding configuration, and quantitative atomic force microscopy to study the nanoscale topography and nanotribological properties. The films were grown on SiO{sub 2} after mechanically polishing the surface with detonation synthesized nanodiamond powder, followed by ultrasonication in a methanol solution containing additional nanodiamond powder. The sp{sup 2} fraction, morphology, and chemistry of the as-etched underside are distinct from the topside, exhibiting a higher sp{sup 2} fraction, some oxidized carbon, and a smoother morphology. The nanoscale single-asperity work of adhesion between a diamond nanotip and the as-etched UNCD underside is far lower than for a silicon-silicon interface (59.2{+-}2 vs 826{+-}186 mJ/m{sup 2}, respectively). Exposure to atomic hydrogen dramatically reduces nanoscale adhesion to 10.2{+-}0.4 mJ/m{sup 2}, at the level of van der Waals' interactions and consistent with recent ab initio calculations. Friction is substantially reduced as well, demonstrating a direct link between the surface chemistry and nanoscale friction. The proposed mechanism, supported by the detailed surface spectroscopic analysis, is the elimination of reactive (e.g., C*-), polar (e.g., C=O), and {pi}-bonded (C=C) surface groups, which are replaced by fully saturated, hydrogen-terminated surface bonds to produce an inert surface that interacts minimally with the contacting counterface.

Sumant, A. V.; Grierson, D. S.; Carpick, R. W. [Department of Engineering Physics, University of Wisconsin-Madison, Wisconsin 53706 (United States); Gerbi, J. E. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Carlisle, J. A.; Auciello, O. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-12-15

42

Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties  

NASA Astrophysics Data System (ADS)

We present a comprehensive study of surface composition and nanotribology for ultrananocrystalline diamond (UNCD) surfaces, including the influence of film nucleation on these properties. We describe a methodology to characterize the underside of the films as revealed by sacrificial etching of the underlying substrate. This enables the study of the morphology and composition resulting from the nucleation and initial growth of the films, as well as the characterization of nanotribological properties which are relevant for applications including micro-/nanoelectromechanical systems. We study the surface chemistry, bonding configuration, and nanotribological properties of both the topside and the underside of the film with synchrotron-based x-ray absorption near-edge structure spectroscopy to identify the bonding state of the carbon atoms, x-ray photoelectron spectroscopy to determine the surface chemical composition, Auger electron spectroscopy to further verify the composition and bonding configuration, and quantitative atomic force microscopy to study the nanoscale topography and nanotribological properties. The films were grown on SiO2 after mechanically polishing the surface with detonation synthesized nanodiamond powder, followed by ultrasonication in a methanol solution containing additional nanodiamond powder. The sp2 fraction, morphology, and chemistry of the as-etched underside are distinct from the topside, exhibiting a higher sp2 fraction, some oxidized carbon, and a smoother morphology. The nanoscale single-asperity work of adhesion between a diamond nanotip and the as-etched UNCD underside is far lower than for a silicon-silicon interface ( 59.2±2 vs 826±186mJ/m2 , respectively). Exposure to atomic hydrogen dramatically reduces nanoscale adhesion to 10.2±0.4mJ/m2 , at the level of van der Waals’ interactions and consistent with recent ab initio calculations. Friction is substantially reduced as well, demonstrating a direct link between the surface chemistry and nanoscale friction. The proposed mechanism, supported by the detailed surface spectroscopic analysis, is the elimination of reactive (e.g., C*? ), polar (e.g., C?O ), and ? -bonded (C?C) surface groups, which are replaced by fully saturated, hydrogen-terminated surface bonds to produce an inert surface that interacts minimally with the contacting counterface.

Sumant, A. V.; Grierson, D. S.; Gerbi, J. E.; Carlisle, J. A.; Auciello, O.; Carpick, R. W.

2007-12-01

43

Structural and Physical Characteristics of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Deposited Using a Coaxial Arc Plasma Gun  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) films were formed without initial nucleation using a coaxial arc plasma gun. The UNCD crystallite diameters estimated from the X-ray diffraction peaks were approximately 2 nm. The Fourier transform infrared absorption spectrum exhibited an intense sp3-CH peak that might originate from the grain boundaries between UNCD crystallites whose dangling bonds are terminated with hydrogen atoms. A narrow sp3 peak in the photoemission spectrum implied that the film comprises a large number of UNCD crystallites. Large optical absorption coefficients at photon energies larger than 3 eV that might be due to the grain boundaries are specific to the UNCD/a-C:H films.

Yoshitake, Tsuyoshi; Nakagawa, You; Nagano, Akira; Ohtani, Ryota; Setoyama, Hiroyuki; Kobayashi, Eiichi; Sumitani, Kazushi; Agawa, Yoshiaki; Nagayama, Kunihito

2010-01-01

44

Ultrananocrystalline diamond films with optimized dielectric properties for advanced RF MEMS capacitive switches  

DOEpatents

An efficient deposition process is provided for fabricating reliable RF MEMS capacitive switches with multilayer ultrananocrystalline (UNCD) films for more rapid recovery, charging and discharging that is effective for more than a billion cycles of operation. Significantly, the deposition process is compatible for integration with CMOS electronics and thereby can provide monolithically integrated RF MEMS capacitive switches for use with CMOS electronic devices, such as for insertion into phase array antennas for radars and other RF communication systems.

Sumant, Anirudha V.; Auciello, Orlando H.; Mancini, Derrick C.

2013-01-15

45

Fundamentals and application of materials integration for low-power piezoelectrically actuated ultra-nanocrystalline diamond MEMS/NEMS.  

SciTech Connect

Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical/tribological properties, compromising applications to several projected MEMS/NEMS devices, particularly those that require materials with high Young's modulus for MEMS resonators or low surface adhesion forces for MEMS/NEMS working in conditions with extensive surface contact. Diamond films with superior mechanical/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD{cflx W}) in film form with 2-5 nm grains exhibits excellent properties for high-performance MEMS/NEMS devices. Concurrently, piezoelectric Pb(Zr{sub x}Ti{sub 1-x})O{sub 3} (PZT) films provide high sensitivity/low electrical noise for sensing/high-force actuation at relatively low voltages. Therefore, integration of PZT and UNCD films provides a high-performance platform for advanced MEMS/NEMS devices. This paper describes the bases of such integration and demonstration of low voltage piezoactuated hybrid PZT/UNCD cantilevers.

Auciello, O.; Srinivasan, S.; Hiller, J.; Kabius, B. (Center for Nanoscale Materials); ( MSD)

2009-01-01

46

Enhancement in electron field emission in ultrananocrystalline and microcrystalline diamond films upon 100 MeV silver ion irradiation  

SciTech Connect

Enhanced electron field emission (EFE) behavior was observed in ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films upon irradiation with 100 MeV Ag{sup 9+}-ions in a fluence of 5x10{sup 11} ions/cm{sup 2}. Transmission electron microscopy indicated that while the overall crystallinity of these films remained essentially unaffected, the local microstructure of the materials was tremendously altered due to heavy ion irradiation, which implied that the melting and recrystallization process have occurred along the trajectory of the heavy ions. Such a process induced the formation of interconnected nanocluster networks, facilitating the electron conduction and enhancing the EFE properties for the materials. The enhancement in the EFE is more prominent for MCD films than that for UNCD films, reaching a low turn-on field of E{sub 0}=3.2 V/mum and large EFE current density of J{sub e}=3.04 mA/cm{sup 2} for 5x10{sup 11} ions/cm{sup 2} heavy ion irradiated samples.

Chen, H.-C.; Palnitkar, Umesh; Pong, W.-F.; Lin, I-N. [Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China); Singh, Abhinav Pratap; Kumar, Ravi [Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110007 (India)

2009-04-15

47

Ultrananocrystalline diamond nano-pillars synthesized by microwave plasma bias-enhanced nucleation and bias-enhanced growth in hydrogen-diluted methane  

NASA Astrophysics Data System (ADS)

Bias-enhanced nucleation and growth of ultrananocrystalline diamond (UNCD) nano-pillars on silicon substrates by low-pressure microwave plasma chemical vapor deposition in a hydrogen-rich gas mixture with methane is reported. Direct-current biasing of the substrate in a constant-current mode is applied to substrates, which are pre-heated to 800 °C, to result in a negative bias voltage of greater than 350 V throughout the nucleation and growth process. Self-masking by UNCD clusters, angle dependent sputtering of UNCD clusters, and ion-assisted chemical vapor deposition by bias enhanced bombardment of energetic ions are attributed to the formation of UNCD nano-pillars. High-resolution transmission electron microscopy analysis indicates that an interfacial layer exists between the silicon substrate and the UNCD nano-pillars. The porous UNCD film with high-density nano-pillars exhibits excellent optical anti-reflectivity and improved electron field emission characteristics compared to smooth and solid UNCD films.

Chu, Yueh-Chieh; Tu, Chia-Hao; Liu, Chuan-pu; Tzeng, Yonhua; Auciello, Orlando

2012-12-01

48

Enhancing electrical conductivity and electron field emission properties of ultrananocrystalline diamond films by copper ion implantation and annealing  

SciTech Connect

Copper ion implantation and subsequent annealing at 600?°C achieved high electrical conductivity of 95.0 (?cm){sup ?1} for ultrananocrystalline diamond (UNCD) films with carrier concentration of 2.8?×?10{sup 18}?cm{sup ?2} and mobility of 6.8?×?10{sup 2} cm{sup 2}/V s. Transmission electron microscopy examinations reveal that the implanted Cu ions first formed Cu nanoclusters in UNCD films, which induced the formation of nanographitic grain boundary phases during annealing process. From current imaging tunneling spectroscopy and local current-voltage curves of scanning tunneling spectroscopic measurements, it is observed that the electrons are dominantly emitted from the grain boundaries. Consequently, the nanographitic phases presence in the grain boundaries formed conduction channels for efficient electron transport, ensuing in excellent electron field emission (EFE) properties for copper ion implanted/annealed UNCD films with low turn-on field of 4.80?V/?m and high EFE current density of 3.60?mA/cm{sup 2} at an applied field of 8.0?V/?m.

Sankaran, K. J.; Tai, N. H., E-mail: nhtai@mx.nthu.edu.tw, E-mail: inanlin@mail.tku.edu.tw [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Panda, K.; Sundaravel, B. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Lin, I. N., E-mail: nhtai@mx.nthu.edu.tw, E-mail: inanlin@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

2014-02-14

49

All diamond self-aligned thin film transistor  

DOEpatents

A substantially all diamond transistor with an electrically insulating substrate, an electrically conductive diamond layer on the substrate, and a source and a drain contact on the electrically conductive diamond layer. An electrically insulating diamond layer is in contact with the electrically conductive diamond layer, and a gate contact is on the electrically insulating diamond layer. The diamond layers may be homoepitaxial, polycrystalline, nanocrystalline or ultrananocrystalline in various combinations.A method of making a substantially all diamond self-aligned gate transistor is disclosed in which seeding and patterning can be avoided or minimized, if desired.

Gerbi, Jennifer (Champaign, IL)

2008-07-01

50

Fast growth of ultrananocrystalline diamond films by bias-enhanced nucleation and growth process in CH{sub 4}/Ar plasma  

SciTech Connect

This letter describes the fast growth of ultrananocrystalline diamond (UNCD) films by bias-enhanced nucleation and growth process in CH{sub 4}/Ar plasma. The UNCD grains were formed at the beginning of the film's growth without the necessity of forming the amorphous carbon interlayer, reaching a thickness of ?380?nm in 10?min. Transmission electron microscopic investigations revealed that the application of bias voltage induced the formation of graphitic phase both in the interior and at the interface regions of UNCD films that formed interconnected paths, facilitating the transport of electrons and resulting in enhanced electron field emission properties.

Saravanan, A.; Huang, B. R. [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Sankaran, K. J.; Tai, N. H. [Department of Materials Science and Engineering, National TsingHua University, Hsinchu 300, Taiwan (China); Dong, C. L. [Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Lin, I. N., E-mail: inanlin@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

2014-05-05

51

Near-Edge X-ray Absorption Fine Structure Imaging of Spherical and Flat Counterfaces of Ultrananocrystalline Diamond Tribological Contacts: A Correlation of Surface Chemistry and Friction  

SciTech Connect

A recently installed synchrotron radiation near-edge X-ray absorption fine structure (NEXAFS) full field imaging electron spectrometer was used to spatially resolve the chemical changes of both counterfaces from an ultra-nanocrystalline diamond (UNCD) tribological contact. A silicon flat and Si{sub 3}N{sub 4} sphere were both coated with UNCD, and employed to form two wear tracks on the flat in a linear reciprocating tribometer. The first wear track was produced using a new, unconditioned sphere whose surface was thus conditioned during this first experiment. This led to faster run-in and lower friction when producing a second wear track using the conditioned sphere. The large depth of field of the magnetically guided NEXAFS imaging detector enabled rapid, large area spectromicroscopic imaging of both the spherical and flat surfaces. Laterally resolved NEXAFS data from the tribological contact area revealed that both substrates had an as-grown surface layer that contained a higher fraction of sp{sup 2}-bonded carbon and oxygen which was mechanically removed. Unlike the flat, the film on the sphere showed evidence of having graphitic character, both before and after sliding. These results show that the graphitic character of the sphere is not solely responsible for low friction and short run-in. Rather, conditioning the sphere, likely by removing asperities and passivating dangling bonds, leads to lower friction with less chemical modification of the substrate in subsequent tests. The new NEXAFS imaging spectroscopy detector enabled a more complete understanding of the tribological phenomena by imaging, for the first time, the surface chemistry of the spherical counterface which had been in continual contact during wear track formation.

A Konicek; C Jaye; M Hamilton; W Sawyer; D Fischer; R Carpick

2011-12-31

52

Science and technology of ultrananocrystalline diamond (UNCD) thin films for multifunctional devices  

SciTech Connect

MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties, and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors. However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophyllic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments. Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS-MMAs) is 10,000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS-MMA applications. A thin film deposition process has been developed that produces phase-pure nanocrystalline diamond with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. The authors have developed lithographic techniques for the fabrication of diamond microstructure including cantilevers and multi-level devices, acting as precursors to micro-bearings and gears, making nanocrystalline diamond a promising material for the development of high performance MEMS devices.

Auciello, O.; Krauss, A. R.; Gruen, D. M.; Jayatissa, A.; Sumant, A.; Tucek, J.; Mancini, D.; Molodvan, N.; Erdemir, A.; Ersoy, D.; Gardos, M. N.; Busman, H. G.; Meyer, E. M.

2000-08-24

53

Time-Resolved Spectroscopic Observation of Deposition Processes of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films by Using a Coaxial Arc Plasma Gun  

NASA Astrophysics Data System (ADS)

The deposition of ultrananocrystalline diamond (UNCD)/amorphous carbon composite films using a coaxial arc plasma gun in vacuum and, for comparison, in a 53.3 Pa hydrogen atmosphere was spectroscopically observed using a high-speed camera equipped with narrow-band-pass filters. UNCD crystallites with diameters of approximately 1.6 nm were formed even in vacuum. These extremely small crystallites imply that the formation is predominantly due to nucleation without the subsequent growth. Even in vacuum, emissions from C+ ions, C atoms, and C2 dimers lasted for approximately 100 µs, although the emission lifetimes of these species are generally 10 ns. We consider that the nucleation is due to the supersaturated environment containing excited carbon species with large number densities.

Hanada, Kenji; Yoshitake, Tsuyoshi; Nishiyama, Takashi; Nagayama, Kunihito

2010-08-01

54

Influences of repetition rate of arc discharges on hardness and modulus of ultrananocrystalline diamond films prepared by coaxial arc plasma deposition  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films were prepared at different repetition rates of arc discharge by coaxial arc plasma deposition. With increasing repetition rate from 5 to 20 Hz, the hardness decreased from 23 to 11 GPa. The UNCD grain size and sp3/(sp2 + sp3) estimated from powder x-ray diffraction (XRD) and x-ray photoemission spectra decreased from 2.6 to 1.8 nm and from 71 to 62%, respectively. Near-edge x-ray absorption fine-structure and Fourier transform infrared spectroscopic measurements revealed enlarged ?*C–H and sp2-CH peaks, respectively. The formation of sp2-CH bonds at grain boundaries owing to the reduced grain size results in degraded hardness.

Yoshida, Tomohiro; Hanada, Kenji; Gima, Hiroki; Ohtani, Ryota; Sumitani, Kazushi; Setoyama, Hiroyuki; Tominaga, Aki; Yoshitake, Tsuyoshi

2015-01-01

55

Patterning of nanocrystalline diamond films for diamond microstructures useful in MEMS and other devices  

DOEpatents

MEMS structure and a method of fabricating them from ultrananocrystalline diamond films having average grain sizes of less than about 10 nm and feature resolution of less than about one micron . The MEMS structures are made by contacting carbon dimer species with an oxide substrate forming a carbide layer on the surface onto which ultrananocrystalline diamond having average grain sizes of less than about 10 nm is deposited. Thereafter, microfabrication process are used to form a structure of predetermined shape having a feature resolution of less than about one micron.

Gruen, Dieter M. (Downers Grove, IL); Busmann, Hans-Gerd (Bremen, DE); Meyer, Eva-Maria (Bremen, DE); Auciello, Orlando (Bolingbrook, IL); Krauss, Alan R. (late of Naperville, IL); Krauss, Julie R. (Naperville, IL)

2004-11-02

56

Structural and optical properties of DNA layers covalently attached to diamond surfaces.  

PubMed

Label-free detection of DNA molecules on chemically vapor-deposited diamond surfaces is achieved with spectroscopic ellipsometry in the infrared and vacuum ultraviolet range. This nondestructive method has the potential to yield information on the average orientation of single as well as double-stranded DNA molecules, without restricting the strand length to the persistence length. The orientational analysis based on electronic excitations in combination with information from layer thicknesses provides a deeper understanding of biological layers on diamond. The pi-pi* transition dipole moments, corresponding to a transition at 4.74 eV, originate from the individual bases. They are in a plane perpendicular to the DNA backbone with an associated n-pi* transition at 4.47 eV. For 8-36 bases of single- and double-stranded DNA covalently attached to ultra-nanocrystalline diamond, the ratio between in- and out-of-plane components in the best fit simulations to the ellipsometric spectra yields an average tilt angle of the DNA backbone with respect to the surface plane ranging from 45 degrees to 52 degrees . We comment on the physical meaning of the calculated tilt angles. Additional information is gathered from atomic force microscopy, fluorescence imaging, and wetting experiments. The results reported here are of value in understanding and optimizing the performance of the electronic readout of a diamond-based label-free DNA hybridization sensor. PMID:18558777

Wenmackers, Sylvia; Pop, Simona D; Roodenko, Katy; Vermeeren, Veronique; Williams, Oliver A; Daenen, Michael; Douhéret, Olivier; D'Haen, Jan; Hardy, An; Van Bael, Marlies K; Hinrichs, Karsten; Cobet, Christoph; vandeVen, Martin; Ameloot, Marcel; Haenen, Ken; Michiels, Luc; Esser, Norbert; Wagner, Patrick

2008-07-15

57

Science and technology of piezoelectric/diamond heterostructures for monolithically integrated high performance MEMS/NEMS/CMOS devices.  

SciTech Connect

This paper describes the fundamental and applied science performed to integrate piezoelectric PbZr{sub x}Ti{sub 1-x}O{sub 3} and AlN films with a novel mechanically robust ultrananocrystalline diamond layer to enable a new generation of low voltage/high-performance piezoactuated hybrid piezoelectric/diamond MEMS/NEMS devices.

Auciello, O.; Sumant, A. V.; Hiller, J.; Kabius, B.; Ma, Z.; Srinivasan, S. (Center for Nanoscale Materials); ( MSD); (Univ. of Wisconsin at Madison); (INTEL)

2008-12-01

58

Nanostructured diamond layers enhance the infrared spectroscopy of biomolecules.  

PubMed

We report on the fabrication and practical use of high-quality optical elements based on Au mirrors coated with diamond layers with flat, nanocolumnar, and nanoporous morphologies. Diamond layers (100 nm thickness) are grown at low temperatures (about 300 °C) from a methane, carbon dioxide, and hydrogen gas mixture by a pulsed microwave plasma system with linear antennas. Using grazing angle reflectance (GAR) Fourier transform infrared spectroscopy with p-polarized light, we compare the IR spectra of fetal bovine serum proteins adsorbed on diamond layers with oxidized (hydrophilic) surfaces. We show that the nanoporous diamond layers provide IR spectra with a signal gain of about 600% and a significantly improved sensitivity limit. This is attributed to its enhanced internal surface area. The improved sensitivity enabled us to distinguish weak infrared absorption peaks of <10-nm-thick protein layers and thereby to analyze the intimate diamond-molecule interface. PMID:24524343

Kozak, Halyna; Babchenko, Oleg; Artemenko, Anna; Ukraintsev, Egor; Remes, Zdenek; Rezek, Bohuslav; Kromka, Alexander

2014-03-01

59

Theoretical study on SAW characteristics of layered structures including a diamond layer  

Microsoft Academic Search

Diamond has the highest surface acoustic wave (SAW) velocity among all materials and thus can provide much advantage for fabrication of high frequency SAW devices when it is combined with a piezoelectric thin film. Basic SAW properties of layered structures consisting of a piezoelectric material layer, a diamond layer and a substrate were examined by theoretical calculation. Rayleigh mode SAW's

Hideaki Nakahata; Akihiro Hachigo; Kenjiro Higaki; Satoshi Fujii; Shin-ichi Shikata; Naoji Fujimori

1995-01-01

60

Effect of pretreatment bias on the nucleation and growth mechanisms of ultrananocrystalline diamond films via bias-enhanced nucleation and growth: An approach to interfacial chemistry analysis via chemical bonding mapping  

SciTech Connect

The effect of pretreatment bias on the nucleation and growth mechanisms of the ultrananocrystalline diamond (UNCD) films on the Si substrate via bias-enhanced nucleation and bias-enhanced growth (BEN-BEG) was investigated using cross-sectional high-resolution transmission electron microscopy, chemical bonding mapping, and Raman spectroscopy. The mirror-polished substrate surface showed the formation of a triangular profile produced by a dominant physical sputtering mechanism induced by ion bombardment of ions from the hydrogen plasma accelerated toward the substrate due to biasing and a potential hydrogen-induced chemical reaction component before synthesizing the UNCD films. The BEN-BEG UNCD films grown on the Si substrate with biased and unbiased pretreatments in the hydrogen plasma were compared. In the case of the bias-pretreated substrate, the SiC phases were formed at the peaks of the Si surface triangular profile due to the active unsaturated Si bond and the enhanced local electrical field. The UNCD grains grew preferentially at the peaks of the triangular substrate surface profile and rapidly covered the amorphous carbon (a-C) and oriented graphite phases formed in the valley of the surface profile. In the case of the substrate with unbiased pretreatment, the SiC phases were formed via the reactions between the hydrocarbon species and the active Si atoms released from the substrate with assistance of the hydrogen plasma. The UNCD grains nucleated on the nucleating sites consisting of the SiC, a-C, and graphite phases. Growth mechanisms for the BEN-BEG UNCD films on both Si substrates were proposed to elucidate the different nucleation processes. Applying bias on the Si substrate pretreated in the hydrogen plasma optimized the nucleation sites for growth of UNCD grains, resulting in the low content of the nondiamond phases in UNCD films.

Zhong, X. Y.; Hiller, J. M. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chen, Y. C.; Tai, N. H. [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Lin, I. N. [Department of Physics, Tamkamg University, Tamsui 251, Taiwan (China); Auciello, O. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2009-02-01

61

Diamond-like phases prepared from graphene layers  

NASA Astrophysics Data System (ADS)

The geometrically optimized structure of ten carbon diamond-like phases obtained by crosslinking graphene layers has been calculated using the density functional theory method and the structural parameters, densities, sublimation energies, and densities of electron states have been determined. Bulk moduli of diamond-like phases have been calculated using the PM3 semiempirical quantum-mechanical method. The X-ray powder diffraction patterns have been calculated based on structural parameters. These diffraction patterns can be used to identify new phases.

Belenkov, E. A.; Greshnyakov, V. A.

2015-01-01

62

Diamonds  

NSDL National Science Digital Library

The first site related to diamonds comes from the American Museum of Natural History entitled The Nature of Diamonds (1). A comprehensive site, visitors can learn about what a diamond is, its related history, mining, industry and technology use, and more. The next site, offered by De Beers Industrial Diamonds (2), offers a history of industrial diamond use as well as a look at their various applications such as saw and wheel grits. The third site, Industrial Diamonds Statistics and Information (3), is maintained by the US Geological Survey. Various publications related to diamonds can be found here, including yearly mineral commodity summaries and mineral yearbooks. Next, a companion Web site to the PBS broadcast "The Diamond Deception" (4) chronicles the efforts to create synthetic diamonds. The site contains the science behind the sparkle, diamonds on other planets, an interactive look inside diamonds, and more. The fifth site comes from HowThingsWork.com that is called How Diamonds Work (5). Descriptions of the origin of diamonds, their properties, famous diamonds, etc., are offered here. Next is The Science of Diamonds (6) site, offered by DiamondCutters.com. Uniquely offered is a description of the diamond cutting process along with other diamond science and history information. From a University of Wisconsin Geology Course Web site comes a photographic gallery called Diamonds (7). Dozens of photographs of diamonds, colored diamonds, and synthetic and diamond simulants can be found here. Lastly, a lesson plan entitled The Hope Diamond Legend (8) is offered by Indiana Academy. Among other things, students can learn that carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, including synthetic polymers, oils, and the large molecules essential to life.

Brieske, Joel A.

2002-01-01

63

Diamond Deposition on WC/Co Alloy with a Molybdenum Intermediate Layer  

NASA Astrophysics Data System (ADS)

It is known that in the condition of chemical vapor deposition (CVD) diamond process, molybdenum is capable of forming carbide known as the "glue" which promotes growth of the CVD diamond, and aids its adhesion by (partial) relief of stresses at the interface. Furthermore, the WC grains are reaction bonded to the Mo2C phase. Therefore, molybdenum is a good candidate material for the intermediate layer between WC-Co substrates and diamond coatings. A molybdenum intermediate layer of 1-3 ?m thickness was magnetron sputter-deposited on WC/Co alloy prior to the deposition of diamond coatings. Diamond films were deposited by hot filament chemical vapor deposition (HFCVD). The chemical quality, morphology, and crystal structure of the molybdenum intermediate layer and the diamond coatings were characterized by means of SEM, EDX, XRD and Raman spectroscopy. It was found that the continuous Mo intermediate layer emerged in spherical shapes and had grain sizes of 0.5-1.5 ?m after 30 min sputter deposition. The diamond grain growth rate was slightly slower as compared with that of uncoated Mo layer on the WC-Co substrate. The morphologies of the diamond films on the WC-Co substrate varied with the amount of Mo and Co on the substrate. The Mo intermediate layer was effective to act as a buffer layer for both Co diffusion and diamond growth.

Liu, Sha; Yu, Zhi-Ming; Yi, Dan-Qing

64

Lamb Wave Characteristics of Composite Plates Including a Diamond Layer with Distinct Electrode Arrangements  

NASA Astrophysics Data System (ADS)

Diamond films have been utilized to develop surface acoustic wave filters and micromechanical resonators because of the highest acoustic wave velocity and largest product of frequency and quality factor (f.Q) of diamond among all materials. A theoretical analysis of Lamb wave characteristics in multilayer piezoelectric plates including a diamond layer is presented in this paper. Formulae for effective permittivity are derived using the transfer matrix method and are further employed to calculate Lamb wave phase velocity dispersions. The electromechanical coupling coefficients (ECCs) are also calculated exactly by Green's function method. Detailed calculations are carried out for ZnO/diamond and AlN/diamond composite plates with four distinct electrode arrangements. Results show that the ZnO/diamond structure yields a phase velocity of 6420 m/s and a large ECC of 7.41%, which makes it suitable for high-frequency wideband filter applications. Moreover, in the AlN/diamond structure, the S0 mode exhibits a large phase velocity of up to 10.3 km/s and a moderate ECC of 1.97%. Such favorable characteristics are expected to contribute to the development of AlN/diamond Lamb wave oscillators operating at approximately 5-10 GHz without the need for a sub-micrometer-resolution lithographic process. Therefore, both ZnO/diamond and AlN/diamond Lamb wave devices are highly promising candidates for RF devices in modern communication systems with advantages over conventional surface acoustic wave devices.

Chen, Yung-Yu

2013-07-01

65

Graphene-on-diamond devices with increased current-carrying capacity: carbon sp2-on-sp3 technology.  

PubMed

Graphene demonstrated potential for practical applications owing to its excellent electronic and thermal properties. Typical graphene field-effect transistors and interconnects built on conventional SiO(2)/Si substrates reveal the breakdown current density on the order of 1 ?A/nm(2) (i.e., 10(8) A/cm(2)), which is ~100× larger than the fundamental limit for the metals but still smaller than the maximum achieved in carbon nanotubes. We show that by replacing SiO(2) with synthetic diamond, one can substantially increase the current-carrying capacity of graphene to as high as ~18 ?A/nm(2) even at ambient conditions. Our results indicate that graphene's current-induced breakdown is thermally activated. We also found that the current carrying capacity of graphene can be improved not only on the single-crystal diamond substrates but also on an inexpensive ultrananocrystalline diamond, which can be produced in a process compatible with a conventional Si technology. The latter was attributed to the decreased thermal resistance of the ultrananocrystalline diamond layer at elevated temperatures. The obtained results are important for graphene's applications in high-frequency transistors, interconnects, and transparent electrodes and can lead to the new planar sp(2)-on-sp(3) carbon-on-carbon technology. PMID:22329428

Yu, Jie; Liu, Guanxiong; Sumant, Anirudha V; Goyal, Vivek; Balandin, Alexander A

2012-03-14

66

Effects of conducting layers on surface acoustic wave in AlN films on diamond  

NASA Astrophysics Data System (ADS)

The interdigital transducer (IDT)/AlN/conducting layer/diamond structures are investigated in this study to design surface acoustic wave (SAW) devices in the super high frequency band. Simulation results using the finite element method show that a thin conducting layer can effectively increase the coupling coefficient and, thus, broaden the bandwidth of SAW devices. For the Sezawa mode, it is illustrated that using a Ti layer with a layer thickness-to-wavelength ratio of 0.02 the maximum coupling coefficient is 2.546% and the associated SAW phase velocity is 10657 m/s at the AlN films' thickness-to-wavelength ratio of 0.14. This coupling coefficient is 105% higher than that in the IDT/AlN/diamond structure. The research results can be applied to design SAW devices using diamond based structures in the super high frequency band.

Sung, C. C.; Chiang, Y. F.; Ro, R.; Lee, R.; Wu, S.

2009-12-01

67

Enhancement of the nucleation of smooth and dense nanocrystalline diamond films by using molybdenum seed layers  

NASA Astrophysics Data System (ADS)

A method for the nucleation enhancement of nanocrystalline diamond (NCD) films on silicon substrates at low temperature is discussed. A sputter deposition of a Mo seed layer with thickness 50 nm on Si substrates was applied followed by an ultrasonic seeding step with nanosized detonation diamond powders. Hot-filament chemical vapor deposition (HF-CVD) was used to nucleate and grow NCD films on substrates heated up at 550 °C. The nucleation of diamond and the early stages of NCD film formation were investigated at different methane percentages in methane/hydrogen gas mixtures by atomic force microscopy, micro-Raman spectroscopy, scanning electron microscopy, and grazing incidence x-ray analyses in order to gain specific insight in the nucleation process of NCD films. The nucleation kinetics of diamond on the Mo-coated Si substrates was found to be up to ten times higher than on blank Si substrates. The enhancement of the nucleation of diamond on thin Mo interlayers results from two effects, namely, (a) the nanometer rough Mo surface shows an improved embedding of ultrasonically introduced nanosized diamond seeds that act as starting points for the diamond nucleation during HF-CVD and (b) the rapid carbonization of the Mo surface causes the formation of Mo2C onto which diamond easily nucleates. The diamond nucleation density progressively increases at increasing methane percentages and is about 5×1010 cm-2 at 4.0% methane. The improved nucleation kinetics of diamond on Mo interlayers facilitates the rapid formation of NCD films possessing a very low surface roughness down to ˜6 nm, and allows a submicron thickness control.

Buijnsters, J. G.; Vázquez, L.; van Dreumel, G. W. G.; ter Meulen, J. J.; van Enckevort, W. J. P.; Celis, J. P.

2010-11-01

68

Integrated microwave (centimeter-range) modulator on polycrystalline diamond layers  

NASA Astrophysics Data System (ADS)

Measuring data for the parameters of a microstrip switching superhigh-frequency integrated circuit on a 100-?m-thick polycrystalline diamond film are reported. Measurements are taken in the frequency range 3-7 GHz. It is shown that the decay in developmental modulators is no greater than 1.5 dB in the on state and no less than 29 dB in the off state. Physicochemical analysis of the multilayer contact metallization technology as applied to synthetic diamond and a silicon p-i-n diode is carried out. The metallization is shown to be stable up to 400°C.

Basanets, V. V.; Boltovets, N. S.; Gutsul, A. V.; Zorenko, A. V.; Ral'chenko, V. G.; Belyaev, A. E.; Klad'ko, V. P.; Konakova, R. V.; Kudrik, Ya. Ya.; Kuchuk, A. V.; Milenin, V. V.

2013-03-01

69

Electrospray deposition of diamond nanoparticle nucleation layers for subsequent CVD diamond growth  

E-print Network

the particles) via the corona effect and accelerates them towards a grounded substrate. The technology has found, resulting in a uniform but dense coating of diamond particles. The potential difference pulls the suspension experimental setup which is detailed in Fig.1. Approximately 1 ml of the colloidal suspension (i.e. nanodiamond

Bristol, University of

70

Analysis of coating fracture and substrate plasticity induced by spherical indentors: diamond and diamond-like carbon layers on steel substrates  

Microsoft Academic Search

Hard coatings as diamond or diamond-like carbon (DLC) layers are widely used as protective coatings on metal substrates, such as steel or hard metal. Failure mechanisms of the substrate\\/coating composite are studied in this paper through a parametric elastic-plastic finite element analysis, for the common load case of the indentation of spherical bodies into a layered surface considering a wide

J. Michler; E Blank

2001-01-01

71

Epitaxial synthesis of diamond layers on a monocrystalline diamond substrate in a torch microwave plasmatron  

SciTech Connect

The epitaxial growth of a diamond single-crystal film in a torch microwave discharge excited by a magnetron of a domestic microwave oven with the power of {<=}1 kW in an argon-hydrogen-methane mixture with a high concentration of methane (up to 25% with respect to hydrogen) at atmospheric pressure on a sub-strate of a synthetic diamond single crystal (HPHP) with the orientation (100) and 4 Multiplication-Sign 4 mm in size is obtained. A discharge with the torch diameter of {approx}2 mm and the concentration of the microwave power absorbed in the torch volume of >10{sup 3} W/cm{sup 3} is shown to be effective for epitaxial enlargement of a single crystal of synthetic diamond. The structure of the deposited film with the thickness up to 10 {mu}m with high-quality morphology is investigated with an optical microscope as well as using the methods of the Raman scattering and scanning electron microscopy.

Sergeichev, K. F., E-mail: kserg@fpl.gpi.ru; Lukina, N. A. [Prokhorov Institute of General Physics (Russian Federation)

2011-12-15

72

Electrical properties of lithium-implanted layers on synthetic diamond  

Microsoft Academic Search

Lithium implantation (40 and 50 keV; doses of 2 × 1016 and 4 × 1016 cm?2) has been performed in several synthetic and natural diamond crystals at room temperature (RT) and 850–900 °C (high temperature (HT) implantation). In contrast with the case of the RT implantation, the HT implantation did not result in radiation-induced surface graphitization. The samples implanted at

R. Job; M. Werner; A. Denisenko; A. Zaitsev; W. R. Fahrner

1996-01-01

73

Hybrid sensors based on colour centres in diamond and piezoactive layers  

NASA Astrophysics Data System (ADS)

The ability to measure weak signals such as pressure, force, electric field and temperature with nanoscale devices and high spatial resolution offers a wide range of applications in fundamental and applied sciences. Here we present a proposal for a hybrid device composed of thin film layers of diamond with colour centres and piezoactive elements for the transduction and measurement of physical signals. The magnetic response of a piezomagnetic layer to an external stress or a stress induced by a signal is shown to affect significantly the spin properties of nitrogen-vacancy centres in diamond. Under ambient conditions, realistic environmental noise and material imperfections, we show that this hybrid device can achieve significant improvements in sensitivity over the pure diamond-based approach in combination with nanometre-scale spatial resolution. Furthermore, the proposed hybrid architecture offers novel possibilities for engineering strong coherent couplings between nanomechanical oscillator and solid state spin qubits.

Cai, Jianming; Jelezko, Fedor; Plenio, Martin B.

2014-06-01

74

Slide diamond burnishing of tool steels with adhesive coatings and diffusion layers  

E-print Network

Slide diamond burnishing of tool steels with adhesive coatings and diffusion layers W. Brostow*1 modification of selected tool steels. The steels were covered with adhesive coatings of the hard chrome type in manufacturing tools and structural elements in automotive and aerospace industries. Keywords: Tool steels, Slide

North Texas, University of

75

Using copper substrate to enhance electron field emission properties of carbon nanotube/diamond double-layered structure  

NASA Astrophysics Data System (ADS)

Vertically aligned carbon nanotube (CNT)/diamond double-layered structure was synthesized on copper (Cu) substrate by hot-filament chemical vapor deposition. The structure was characterized by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The results show that the diamond layer has good adhesion to the Cu substrate and the CNTs have direct contact with the diamond layer. Field electron emission measurement shows that the double-layered structure on copper has very good emission stability and a much lower turn-on field than that on silicon (Si).

Yang, Lezhi; Sujith Kumar, C. S.; Li, Yuan-shi; Niakan, Hamid; Zhang, Chunzi; Hirose, Akira; Aravind, Suresh; Yang, Qiaoqin

2015-01-01

76

Characterization of molecular and biomolecular layers on diamond thin films by infrared reflection-absorption spectroscopy  

Microsoft Academic Search

We explore the use of single-bounce infrared reflection-absorption spectroscopy (IRRAS) to characterize molecular and biomolecular layers on doped and undoped diamond thin films on silicon substrates. Experimental measurements of thin layers of poly(methyl methacrylate) (PMMA) as a function of polarization and angle of incidence were used to characterize the intensity, frequency, and symmetry of the vibrational features. Fresnel multilayer reflectivity

Robert J. Hamers; Courtney Stavis; Ankit Pokhrel; Ryan Franking; Rose E. Ruther; Xiaoyu Wang; Michelle C. Cooperrider; Hongjun Zheng; John A. Carlisle; James E. Butler

2011-01-01

77

Hexagonal Diamonds (Lonsdaleite) Discovered in the K/T Impact Layer in Spain and New Zealand  

NASA Astrophysics Data System (ADS)

We present the first evidence from Cretaceous-Tertiary (K/T) boundary clay and rock for shocked hexagonal nanodiamonds (lonsdaleite), these being found in concentrations greater than 50 ppm at Needles Point, New Zealand, and Caravaca, Spain. This is also the first evidence for K/T diamonds of any kind outside of North America. No diamonds were detected immediately above or below the impact layer. Cubic diamonds have been reported earlier from North American K/T sediments by Carlisle and Braman (1991; 45 ppm) and Hough et al. (1997; 18 ppm), but lonsdaleite was not detected. Carlisle and Braman suggested that the cubic diamonds arrived already formed within the impactor, but Hough argued that they were shock-produced by the impact with Earth. Hence, it is not yet clear that K/T cubic diamonds were formed through shock. Lonsdaleite does not co-occur with terrestrial diamonds but is found with cubic diamonds in ET impact craters (e.g., Popigai, Sudbury). Both also have been reported in the impact layer of the proposed Younger Dryas impact event at 12.9 ka. Lonsdaleite is formed by shocking carbonaceous material, e. g., graphite, under extreme conditions of pressure and temperature (more than 15 GPa at more than 1000° C), thus making this mineral an excellent impact-shock indicator (DeCarli, 2002). Although lonsdaleite is also contained in meteorites, such as ureilites, there appears to be a consensus of opinion that crater-related lonsdaleite formed during ET impact. K/T sediment samples were acquired from the boundary layer, as well as above and below. To extract the diamonds from the sediments, we utilized the protocol from Amari (1994) and Huss and Lewis (1995), but modified their methodology after determining that phosphoric and perchloric acids oxidize metastable lonsdaleite. We extracted the diamonds successfully after eliminating those acids, which may explain why lonsdaleite was not apparent in extractions by others. The extracted lonsdaleite was analyzed by transmission electron microscopy (TEM) and by selected area diffraction (SAED), which displayed characteristic reflections corresponding to lattice planar spacings of 2.18, 1.26, 1.09, and 0.82 A. A scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS) confirmed their carbon composition. With exposure to long-wave ultraviolet (365 nm) radiation, clusters of lonsdaleite crystals exhibited a blue fluorescence that is characteristic of many diamonds. Individual crystals were angular to sub-rounded in shape and ranged in size from 20 to 1000 nm, with a mean size of about 50 nm. This discovery represents (1) the strongest available evidence for K/T diamond formation during the impact; (2) the first discovery of K/T diamonds outside North America; and (3) the first occurrence of any form of K/T diamonds in the Southern Hemisphere, about 12,000 km from the Chicxulub Crater in Mexico.

Bunch, T. E.; Wittke, J. H.; West, A.; Kennett, J. P.; Kennett, D. J.; Que Hee, S. S.; Wolbach, W. S.; Stich, A.; Mercer, C.; Weaver, J. C.

2008-12-01

78

Systematic studies on transition layers of carbides between CVD diamond films and substrates of strong carbide-forming elements  

NASA Astrophysics Data System (ADS)

The nucleation and growth mechanism of polycrystalline diamond films prepared by chemical vapor deposition (CVD) have received increasing research interest. To verify the existence of the transition layers between CVD diamond films and substrates, and to investigate their composition, structure and properties are very meaningful research topics for understanding the mechanism of diamond film growth and developing the applications of CVD diamond films. In this work, the transition layers of carbides for the substrates of molybdenum (Mo), silicon (Si), tungsten (W), tantalum (Ta), and niobium (Nb) and titanium (Ti) have been systematically studied by x-ray diffraction characterization. The experiment results have provided evidence of the existence of transition layers and have revealed that the transition layers are polycrystalline Mo2C, SiC, WC and W2C, TaC and Ta2C, NbC and Nb2C, as well as TiC for the substrates of Mo, Si, W, Ta, Nb and Ti, respectively.

Jiang, Xiang-Liu; Zhang, Fang-Qing; Li, Jiang-Qi; Yang, Bin; Chen, Guang-Hua

1991-12-01

79

Accurate Raman spectroscopy of diamond-like carbon films deposited by an anode layer source  

Microsoft Academic Search

Diamond-like carbon (DLC) films deposited by a new room-temperature deposition method were critically investigated by Raman spectroscopy. A gridless, linear anode layer source was fed with acetylene at different flow rates at varying applied voltages producing highly adhesive and transparent DLC films. Raman spectra showed a correlation between the intensity ratio ID\\/IG and the voltage applied to the ion source.

M. Kahn; M. Cekada; R. Berghauser; W. Waldhauser; C. Bauer; C. Mitterer; E. Brandstätter

2008-01-01

80

Temperature dependent creation of nitrogen-vacancy centers in single crystal CVD diamond layers  

NASA Astrophysics Data System (ADS)

In this work, we explore the ability of plasma assisted chemical vapor deposition (PACVD) operating under high power densities to produce thin high-quality diamond layers with a controlled doping with negatively-charged nitrogen-vacancy (NV-) centers. This luminescent defect possesses specific physical characteristics that make it suitable as an addressable solid-state electron spin for measuring magnetic fields with unprecedented sensitivity. To this aim, a relatively large number of NV- centers (> 10^12 cm^-3) should ideally be located in a thin diamond layer (a few tens of nm) close to the surface which is particularly challenging to achieve with the PACVD technique. Here we show that intentional temperature variations can be exploited to tune NV- creation efficiency during growth, allowing engineering complex stacking structures with a variable doping. Because such a temperature variation can be performed quickly and without any change of the gas phase composition, thin layers can be grown. Measurements show that despite the temperature variations, the luminescent centers incorporated using this technique exhibit spin coherence properties similar to those reached in ultra-pure bulk crystals, which suggests that they could be successfully employed in magnetometry applications.

Tallaire, A.; Lesik, M.; Jacques, V.; Pezzagna, S.; Mille, V.; Brinza, O.; Meijer, J.; Abel, B.; Roch, J. F.; Gicquel, A.; Achard, J.

2015-01-01

81

High current density diamond based electron emitters for vacuum thermionic energy conversion  

NASA Astrophysics Data System (ADS)

Vacuum thermionic energy conversion utilizes thermionic emission to release electrons from an emitter into vacuum and collection at a counter-electrode. In our approach for an efficient thermionic emitter a multi-layer diamond thin film structure was synthesized by plasma-assisted CVD on a metallic substrate with controlled surface roughness including a nanodiamond pretreatment step. Introduction of nitrogen during ultra-nanocrystalline diamond (UNCD) film growth resulted in a low resistivity interstitial layer significantly enhancing emission current density which can be related to the Richardson constant. The top layer of polycrystalline nitrogen doped diamond was exposed to a hydrogen plasma inducing negative electron affinity characteristic presenting a low effective emitter work function < 1.3 eV. Thermionic emission from this material commences at temperatures as low as 260^oC and observes the law of Richardson -- Dushman. From a data fit a significant Richardsons constant > 2 A/cm^2 K^2 was extracted and at a temperature of 500^oC a thermionic emission current > 5 mA was measured. This may well be the highest current density reported from a thermionic emitter operating at the moderate temperature of 500^oC.

Koeck, Franz; Nemanich, Robert

2010-03-01

82

Response function measurement of layered type CVD single crystal diamond radiation detectors for 14 MeV neutrons  

SciTech Connect

Response function measurement of layered-type chemical vapor deposition single crystal diamond radiation detectors for 14 MeV neutrons was carried out. The detector had a layered structure that was composed of a boron-doped diamond layer of 0.5 {mu}m in thickness and a nondoped diamond layer of 20 {mu}m on an inexpensive high pressure and high temperature-type Ib diamond substrate. The detector had energy resolution of 2.6% for 5.5 MeV {alpha} particles. This experiment was mainly carried out in order to understand the present status of the detector as a 14 MeV neutron spectrometer and an extent of charge trapping. As result, a peak caused by the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be reactions was clearly observed; the best energy resolution of 6% as for a synthetic diamond radiation detector was achieved. Detection efficiency was 3.2x10{sup -7} counts/unit neutron fluence. However, taking the energy resolution for {alpha} particles, etc., into account, the energy resolution for 14 MeV neutrons was not so high. Further improvement based on better crystal growth is indispensable.

Kaneko, J.H.; Teraji, T.; Hirai, Y.; Shiraishi, M.; Kawamura, S.; Yoshizaki, S.; Ito, T.; Ochiai, K.; Nishitani, T.; Sawamura, T. [Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan); Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan)

2004-10-01

83

Conductive layers in diamond formed by hydrogen ion implantation and annealing  

NASA Astrophysics Data System (ADS)

High conductivity is extremely difficult to obtain in diamond due to its wide band gap and low solubility of dopands. The goal of the investigation was to form a conductor inside HPHT synthetic diamond plates with initial high sheet resistivity ?s (˜1012 ?/sq) for 400 ?m thickness. We used metastable character of diamond structures relative to the graphitization of defective layers formed by 50 keV hydrogen molecular ions at high fluence ? = (1-13) × 1016 cm-2 ion implantation. High temperature (HT) (500-1600 °C) and vacuum or high pressure (VP/HP) (3 × 10-3/4 × 109 Pa) thermal annealing were chosen to provide the annealing regimes where the graphitic carbon is the most stable phase. Sheet resistance, dropped down up to nine orders of magnitude (?s ˜ 103 ?/sq), as well as Raman spectroscopy, and AFM measurements were used to determine electrical, optical and geometrical properties of multilayered heterostructures formed in the set of experiments. Temperature dependences of the conductivity show, that after highest fluencies and annealing temperatures the conductivity is quasimetallic and electronic system is above metal-insulator transition (MIT). At lower fluences and/or annealing temperatures the system is under MIT with the transport of charge carriers being well described by variable range hopping (VRH) mechanism with variable decay length of wave function for localized states. Two or three order of magnitude differences in the conductivity in VP and HP annealed samples are attributed with the higher dimensions of graphite nanocrystals in the case of vacuum annealing. This suggestion coincides with Raman spectra and optimum hopping length for carrier jumps in VRH model for conductivity in the buried layers.

Popov, V. P.; Safronov, L. N.; Naumova, O. V.; Nikolaev, D. V.; Kupriyanov, I. N.; Palyanov, Yu. N.

2012-07-01

84

Effects of metal buffer layer on characteristics of surface acoustic waves in ZnO/metal/diamond structures  

NASA Astrophysics Data System (ADS)

The interdigital transducer (IDT)/ZnO/metal/diamond structure is investigated for use in the design surface acoustic wave (SAW) devices in the super-high-frequency (SHF) band. Simulation results indicate that adding a metal buffer layer with a finite thickness significantly increases the coupling coefficient. In the Sezawa mode, the coupling coefficient is 4.71% when an Al interlayer is applied. This coupling coefficient is 75% and 77% larger than those in the IDT/ZnO/diamond and IDT/ZnO/shorted surface/diamond structures, respectively. The results in this study are useful in designing SAW devices using diamond-based structures with a large coupling coefficient in the SHF band.

Chiang, Yuan-Feng; Sung, Chia-Chi; Ro, Ruyen

2010-04-01

85

Tantalum as a buffer layer in diamond-like carbon coated artificial hip joints.  

PubMed

The acid resistance of tantalum coated and uncoated human hip joint prostheses was studied with commercial CrCoMo acetabular cups. The samples were exposed to 10% HCl solution and the quantities of dissolved Cr, Co, and Mo were measured with proton-induced X-ray emission (PIXE). The absolute quantities were obtained with the use of Cr and Se solution standards. Tantalum coatings (thicknesses 4-6 microm) were prepared in vacuum with magnetron sputtering. Tantalum coating decreased the corrosion rate by a factor of 10(6). As a spinoff from recent wear tests on artificial hip joints it was shown that tantalum has excellent mechanical properties as an intermediate layer of diamond-like carbon (DLC) coatings. When tantalum was tested together with DLC on three metal-on-metal hip joint pairs in a hip simulator, no observable defects occurred during 15 million walking cycles with a periodic 50-300-kg load (Paul curve). PMID:12808604

Kiuru, Mirjami; Alakoski, Esa; Tiainen, Veli-Matti; Lappalainen, Reijo; Anttila, Asko

2003-07-15

86

Growth of micro- and nanocrystalline dual layer composite diamond films by microwave plasma CVD: Influence of CO2 concentration on growth of nano-layer  

NASA Astrophysics Data System (ADS)

The high quality and smooth micro-and nanocrystalline dual layer composite diamond films were successfully prepared using H2/CH4/Ar/CO2 plasma with a synthesis process of nucleation/MCD growth/nucleation/NCD growth. The carbon dioxide content is demonstrated to be important in controlling the NCD layer grain size and growth rate. The influences of carbon dioxide concentration on the morphology, microstructure and growth rate of the deposited NCD layer are investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. It is found that the additional carbonaceous sources supplied by CO2 are favourable to increase the growth rate, and meanwhile, the oxygen related species generated would enhance the etching effect not only to eliminate the non-diamond phase of NCD but also to decrease the growth rate. The appropriate addition of CO2 can increase the high quality and growth rate, decrease the surface roughness. It is demonstrated that adding CO2 strongly affects the contents of various reaction species in plasma, which would determine the growth features of NCD layers. The deposited highly smooth and quality micro-/nano-crystal layered diamond film is also expected to be applicable in surface aroustic wave (SAW) devices and micro-electromechanical systems (MEMS).

Liu, Cong; Wang, Jian-Hua; Weng, Jun

2015-01-01

87

Alumina atomic layer deposition nanocoatings on primary diamond particles using a fluidized bed reactor  

E-print Network

that micron-sized diamond particles can be fluidized with the assistance of vibration. Alumina films are grown as the cutting element in drill bits. Such cutters generally comprise a PDC table formed on a hard metal tungsten

George, Steven M.

88

Sputtered tungsten-based ternary and quaternary layers for nanocrystalline diamond deposition.  

PubMed

Many of today's demanding applications require thin-film coatings with high hardness, toughness, and thermal stability. In many cases, coating thickness in the range 2-20 microm and low surface roughness are required. Diamond films meet many of the stated requirements, but their crystalline nature leads to a high surface roughness. Nanocrystalline diamond offers a smoother surface, but significant surface modification of the substrate is necessary for successful nanocrystalline diamond deposition and adhesion. A hybrid hard and tough material may be required for either the desired applications, or as a basis for nanocrystalline diamond film growth. One possibility is a composite system based on carbides or nitrides. Many binary carbides and nitrides offer one or more mentioned properties. By combining these binary compounds in a ternary or quaternary nanocrystalline system, we can tailor the material for a desired combination of properties. Here, we describe the results on the structural and mechanical properties of the coating systems composed of tungsten-chromium-carbide and/or nitride. These WC-Cr-(N) coatings are deposited using magnetron sputtering. The growth of adherent nanocrystalline diamond films by microwave plasma chemical vapor deposition has been demonstrated on these coatings. The WC-Cr-(N) and WC-Cr-(N)-NCD coatings are characterized with atomic force microscopy and SEM, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and nanoindentation. PMID:22905536

Walock, Michael J; Rahil, Issam; Zou, Yujiao; Imhoff, Luc; Catledge, Shane A; Nouveau, Corinne; Stanishevsky, Andrei V

2012-06-01

89

Young's modulus, fracture strength, and Poisson's ratio of nanocrystalline diamond films  

NASA Astrophysics Data System (ADS)

Young's modulus, fracture stress, and Poisson's ratio are important mechanical characteristics for micromechanical devices. The Poisson's ratio of a material is a good measure to elucidate its mechanical behavior and generally is the negative ratio of transverse to axial strain. A nanocrystalline (NCD) and an ultrananocrystalline (UNCD) diamond sample with grain boundaries of different chemical and structural constitutions have been investigated by an ultrasonic resonance method. For both samples, the elastic moduli are considerably reduced, compared with the elastic modulus of single crystal diamond (sc-diamond). Depending on the chemical and structural constitution of grain boundaries in nano- and ultrananocrystalline diamond different values for Poisson's ratio and for the fracture strength are observed. We found a Poisson's ratio of 0.201 ± 0.041 for the ultrananocrystalline sample and 0.034 ± 0.017 for the nanocrystalline sample. We discuss these results on the basis of a model for granular media. Higher disorder in the grain boundary leads to lower shear stiffness between the single grains and ultimately results in a decrease of Young's and shear modulus and possibly of the fracture strength of the material.

Mohr, Markus; Caron, Arnaud; Herbeck-Engel, Petra; Bennewitz, Roland; Gluche, Peter; Brühne, Kai; Fecht, Hans-Jörg

2014-09-01

90

Band offsets of Al{sub 2}O{sub 3} and HfO{sub 2} oxides deposited by atomic layer deposition technique on hydrogenated diamond  

SciTech Connect

High-k oxide insulators (Al{sub 2}O{sub 3} and HfO{sub 2}) have been deposited on a single crystalline hydrogenated diamond (H-diamond) epilayer by an atomic layer deposition technique at temperature as low as 120 Degree-Sign C. Interfacial electronic band structures are characterized by X-ray photoelectron spectroscopy. Based on core-level binding energies and valence band maximum values, valence band offsets are found to be 2.9 {+-} 0.2 and 2.6 {+-} 0.2 eV for Al{sub 2}O{sub 3}/H-diamond and HfO{sub 2}/H-diamond heterojunctions, respectively. Band gaps of the Al{sub 2}O{sub 3} and HfO{sub 2} have been determined to be 7.2 {+-} 0.2 and 5.4 {+-} 0.2 eV by measuring O 1s energy loss spectra, respectively. Both the Al{sub 2}O{sub 3}/H-diamond and HfO{sub 2}/H-diamond heterojunctions are concluded to be type-II staggered band configurations with conduction band offsets of 1.2 {+-} 0.2 and 2.7 {+-} 0.2 eV, respectively.

Liu, J. W.; Liao, M. Y.; Imura, M. [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Koide, Y. [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Nanofabrication Platform, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Center of Materials Research for Low Carbon Emission, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2012-12-17

91

Photochromism-induced amplification of critical current density in superconducting boron-doped diamond with an azobenzene molecular layer.  

PubMed

A key issue in molecular electronics is the control of electronic states by optical stimuli, which enables fast and high-density data storage and temporal-spatial control over molecular processes. In this article, we report preparation of a photoswitchable superconductor using a heavily boron-doped diamond (BDD) with a photochromic azobenzene (AZ) molecular layer. BDDs electrode properties allow for electrochemical immobilization, followed by copper(I)-catalyzed alkyne-azide cycloaddition (a "click" reaction). Superconducting properties were examined with magnetic and electrical transport measurements, such as field-dependent isothermal magnetization, temperature-dependent resistance, and the low-temperature voltage-current response. These measurements revealed reversible amplification of the critical current density by 55% upon photoisomerization. This effect is explained as the reversible photoisomerization of AZ inducing an inhomogeneous electron distribution along the BDD surface that renormalizes the surface pinning contribution to the critical current. PMID:25494096

Natsui, Keisuke; Yamamoto, Takashi; Akahori, Miku; Einaga, Yasuaki

2015-01-14

92

The ice layer in Uranus and Neptune - Diamonds in the sky  

Microsoft Academic Search

Many of the current models of Uranus and Neptune postulate a three-layer structure, consisting of an inner rocky core, a middle 'ice' layer of fluid, H2O, CH4, NH3 and an outer hydrogen-helium layer of solar composition (Hubbard and McFarland, 1980). The estimated pressures and temperatures of the ice layer ranges from about 6 Mbar and 7,000 K at the inner

Marvin Ross

1981-01-01

93

Industrial diamond  

USGS Publications Warehouse

An overview of the industrial diamond industry is provided. More than 90 percent of the industrial diamond consumed in the U.S. and the rest of the world is manufactured diamond. Ireland, Japan, Russia, and the U.S. produce 75 percent of the global industrial diamond output. In 2000, the U.S. was the largest market for industrial diamond. Industrial diamond applications, prices for industrial diamonds, imports and exports of industrial diamonds, the National Defense Stockpile of industrial diamonds, and the outlook for the industrial diamond market are discussed.

Olson, D.W.

2001-01-01

94

Microstructural evolution of diamond growth during HFCVD  

NASA Technical Reports Server (NTRS)

High resolution transmission electron microscopy (HRTEM) was used to study the nucleation and growth mechanism of diamond by hot filament chemical vapor deposition (HFCVD) process. A novel technique has shown a direct evidence for the formation of the diamond-like carbon layer 8-14 nm thick in which small diamond micro-crystallites were embedded. These diamond micro-crystallites were formed as a result of transformation of diamond-like carbon into diamond. The diamond micro-crystallites present in the amorphous diamond-like carbon layer provided nucleation sites for diamond growth. Large diamond crystallites were observed to grow from these micro-crystallites. The mechanism of diamond growth will be presented based on experimental findings.

Singh, J.

1994-01-01

95

Industrial diamond  

USGS Publications Warehouse

Statistics on the production, consumption, cost, trade, and government stockpile of natural and synthetic industrial diamond are provided. The outlook for the industrial diamond market is also considered.

Olson, D.W.

2003-01-01

96

Diamond Smoothing Tools  

NASA Technical Reports Server (NTRS)

Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors. A diamond smoothing tool according to the proposal would have a smooth spherical surface. For a given finish machining operation, the smoothing tool would be mounted next to the cutting tool. The smoothing tool would slide on the machined surface left behind by the cutting tool, plastically deforming the surface material and thereby reducing the roughness of the surface, closing microcracks and otherwise generally reducing or eliminating microscopic surface and subsurface defects, and increasing the microhardness of the surface layer. It has been estimated that if smoothing tools of this type were used in conjunction with cutting tools on sufficiently precise lathes, it would be possible to reduce the roughness of machined surfaces to as little as 3 nm. A tool according to the proposal would consist of a smoothing insert in a metal holder. The smoothing insert would be made from a diamond/metal functionally graded composite rod preform, which, in turn, would be made by sintering together a bulk single-crystal or polycrystalline diamond, a diamond powder, and a metallic alloy at high pressure. To form the spherical smoothing tip, the diamond end of the preform would be subjected to flat grinding, conical grinding, spherical grinding using diamond wheels, and finally spherical polishing and/or buffing using diamond powders. If the diamond were a single crystal, then it would be crystallographically oriented, relative to the machining motion, to minimize its wear and maximize its hardness. Spherically polished diamonds could also be useful for purposes other than smoothing in finish machining: They would likely also be suitable for use as heat-resistant, wear-resistant, unlubricated sliding-fit bearing inserts.

Voronov, Oleg

2007-01-01

97

Ohmic contact properties of p-type surface conductive layer on H-terminated diamond films prepared by DC arc jet CVD  

NASA Astrophysics Data System (ADS)

With the advantages of high deposition rate and large deposition area, polycrystalline diamond films prepared by direct current (DC) arc jet chemical vapor deposition (CVD) are considered to be one of the most promising materials for high-frequency and high-power electronic devices. In this paper, high-quality self-standing polycrystalline diamond films with the diameter of 100 mm were prepared by DC arc jet CVD, and then, the p-type surface conductive layer with the sheet carrier density of 1011-1013 cm-2 on the H-terminated diamond film was obtained by micro-wave hydrogen plasma treatment for 40 min. Ti/Au and Au films were deposited on the H-terminated diamond surface as the ohmic contact electrode, respectively, afterwards, they were treated by rapid vacuum annealing at different temperatures. The properties of these two types of ohmic contacts were investigated by measuring the specific contact resistance using the transmission line method (TLM). Due to the formation of Ti-related carbide at high temperature, the specific contact resistance of Ti/Au contact gradually decreases to 9.95 × 10-5 ?·cm2 as the temperature increases to 820°C. However, when the annealing temperature reaches 850°C, the ohmic contact for Ti/Au is degraded significantly due to the strong diffusion and reaction between Ti and Au. As for the as-deposited Au contact, it shows an ohmic contact. After annealing treatment at 550°C, low specific contact resistance was detected for Au contact, which is derived from the enhancement of interdiffusion between Au and diamond films.

Liu, Jin-long; Li, Cheng-ming; Zhu, Rui-hua; Chen, Liang-xian; Wang, Jing-jing; Feng, Zhi-hong

2013-08-01

98

On Interlayer Stability and High-Cycle Simulator Performance of Diamond-Like Carbon Layers for Articulating Joint Replacements  

PubMed Central

Diamond like carbon (DLC) coatings have been proven to be an excellent choice for wear reduction in many technical applications. However, for successful adaption to the orthopaedic field, layer performance, stability and adhesion in physiologically relevant setups are crucial and not consistently investigated. In vitro wear testing as well as adequate corrosion tests of interfaces and interlayers are of great importance to verify the long term stability of DLC coated load bearing implants in the human body. DLC coatings were deposited on articulating lumbar spinal disks made of CoCr28Mo6 biomedical implant alloy using a plasma-activated chemical vapor deposition (PACVD) process. As an adhesion promoting interlayer, tantalum films were deposited by magnetron sputtering. Wear tests of coated and uncoated implants were performed in physiological solution up to a maximum of 101 million articulation cycles with an amplitude of ±2° and ?3/+6° in successive intervals at a preload of 1200 N. The implants were characterized by gravimetry, inductively coupled plasma optical emission spectrometry (ICP-OES) and cross section scanning electron microscopy (SEM) analysis. It is shown that DLC coated surfaces with uncontaminated tantalum interlayers perform very well and no corrosive or mechanical failure could be observed. This also holds true in tests featuring overload and third-body wear by cortical bone chips present in the bearing pairs. Regarding the interlayer tolerance towards interlayer contamination (oxygen), limits for initiation of potential failure modes were established. It was found that mechanical failure is the most critical aspect and this mode is hypothetically linked to the ?-? tantalum phase switch induced by increasing oxygen levels as observed by X-ray diffraction (XRD). It is concluded that DLC coatings are a feasible candidate for near zero wear articulations on implants, potentially even surpassing the performance of ceramic vs. ceramic. PMID:24921709

Thorwarth, Kerstin; Thorwarth, Götz; Figi, Renato; Weisse, Bernhard; Stiefel, Michael; Hauert, Roland

2014-01-01

99

On interlayer stability and high-cycle simulator performance of diamond-like carbon layers for articulating joint replacements.  

PubMed

Diamond like carbon (DLC) coatings have been proven to be an excellent choice for wear reduction in many technical applications. However, for successful adaption to the orthopaedic field, layer performance, stability and adhesion in physiologically relevant setups are crucial and not consistently investigated. In vitro wear testing as well as adequate corrosion tests of interfaces and interlayers are of great importance to verify the long term stability of DLC coated load bearing implants in the human body. DLC coatings were deposited on articulating lumbar spinal disks made of CoCr28Mo6 biomedical implant alloy using a plasma-activated chemical vapor deposition (PACVD) process. As an adhesion promoting interlayer, tantalum films were deposited by magnetron sputtering. Wear tests of coated and uncoated implants were performed in physiological solution up to a maximum of 101 million articulation cycles with an amplitude of ±2° and -3/+6° in successive intervals at a preload of 1200 N. The implants were characterized by gravimetry, inductively coupled plasma optical emission spectrometry (ICP-OES) and cross section scanning electron microscopy (SEM) analysis. It is shown that DLC coated surfaces with uncontaminated tantalum interlayers perform very well and no corrosive or mechanical failure could be observed. This also holds true in tests featuring overload and third-body wear by cortical bone chips present in the bearing pairs. Regarding the interlayer tolerance towards interlayer contamination (oxygen), limits for initiation of potential failure modes were established. It was found that mechanical failure is the most critical aspect and this mode is hypothetically linked to the ?-? tantalum phase switch induced by increasing oxygen levels as observed by X-ray diffraction (XRD). It is concluded that DLC coatings are a feasible candidate for near zero wear articulations on implants, potentially even surpassing the performance of ceramic vs. ceramic. PMID:24921709

Thorwarth, Kerstin; Thorwarth, Götz; Figi, Renato; Weisse, Bernhard; Stiefel, Michael; Hauert, Roland

2014-01-01

100

Electronic properties of CVD and synthetic diamond  

Microsoft Academic Search

Transport and contact properties of synthetic IIb- and intrinsic chemical vapor deposition (CVD) -diamond films are discussed. The samples have been investigated by time-of-flight and transient photoconductivity experiments using Cr\\/Au contacts. A hole depletion layer at the Cr\\/Au-IIb-diamond interface and an electron depletion layer at the Cr\\/Au-CVD-diamond interface is detected. The data indicate that our normally undoped CVD-diamond films are

C. E. Nebel; J. Müautnz; M. Stutzmann; R. Zachai; H. Güautttler

1997-01-01

101

Diamond-based capacitive micromachined ultrasonic transducers in immersion.  

PubMed

Diamond is a superior membrane material for capacitive micromachined ultrasonic transducers (CMUTs). By using ultrananocrystalline diamond (UNCD) membrane and plasma-activated wafer bonding technology, a single diamond-based circular CMUT is demonstrated and operated in immersion for the first time. The diamond-based CMUT, biased at 100 V, is excited with a 10-cycle burst of 36 V(p-p) sine signal at 3.5 MHz. Pressure generated on a 2-D plane coincident with the normal of the CMUT is measured using a broadband hydrophone. Peak-to-peak hydrophone voltage measurements along the scan area clearly indicate the main lobe and the side lobes, as theoretically predicted by our directivity function calculations. The peak-to-peak hydrophone voltage on the axial direction of the CMUT is found to be in agreement with our theoretical calculations in the Fraunhofer region (-45 mm diamond-based CMUT is measured for a dc bias of 100 V, and ac excitation with 30-cycle bursts of 9, 36, and 54 V(p-p) sine signal. A peak response at 5.6 MHz is measured for all ac amplitudes. Overall, diamond is shown to be an applicable membrane for CMUT devices and applications. PMID:23357916

Cetin, Ahmet M; Bayram, Baris

2013-02-01

102

Accepted to Diamond and Related Materials A kinetic model of diamond nucleation and silicon carbide interlayer formation during  

E-print Network

Accepted to Diamond and Related Materials A kinetic model of diamond nucleation and silicon carbide intermediate layers on silicon substrates during nucleation and the early stages of diamond deposition have diffusion of carbon atoms into the silicon carbide layer, and the morphology and orientation of the diamond

Dandy, David

103

Investigations of boundary layer formation as a function of nitrogen concentration and reactor pressure during microwave plasma deposition of diamond films  

SciTech Connect

Recent studies within this group have focused on the effects of nitrogen on diamond film growth. Very small concentrations of nitrogen have been shown to enhance CVD diamond film growth, while larger concentrations may result in rough growth. In any CVD growth, within several gas phase mean free paths of the surface, the composition of the gas is perturbed by the effects of the reactions occurring at the surface. A chemical boundary layer with temperature and concentration gradients is formed, through which species diffuse to reach the surface. Boundary layer transport in CVD diamond film growth has been studied for hydrogen, carbon and oxygen species. The transport of nitrogen has been less studied. Also the transport mechanisms and growth are somewhat specific to deposition conditions. The deposition conditions are based on use of a five inch discharge 2.45 GHz microwave plasma reactor, and transport over wide areas has also been less studied. In these investigations, correlated studies of gas phase content and resulting surface morphology are studied as a function of variations in (1) nitrogen concentration and (2) reactor pressure. Previous studies have indicated that formation of and transport through the boundary layer may be sensitive to reactor pressure. Gas phase nitrogen concentration is monitored by OES, CN emission band. Deposition nitrogen concentrations are varied between 15 ppm and 1000 ppm, using an ultrahigh vacuum gas handling system which allows careful control of the gas input variables, down to 10 ppm. The growth and morphology of the series of films are investigated by scanning electron microscopy and atomic force microscopy.

Ayres, V.M.; Farhan, M.; Mossbrucker, J.; Huang, W.S.; Wright, B.; Asmussen, J. [Michigan State Univ., East Lansing, MI (United States). Dept. of Electrical Engineering

1998-12-31

104

Nanofabrication of sharp diamond tips by e-beam lithography and inductively coupled plasma reactive ion etching.  

SciTech Connect

Ultrasharp diamond tips make excellent atomic force microscopy probes, field emitters, and abrasive articles due to diamond's outstanding physical properties, i.e., hardness, low friction coefficient, low work function, and toughness. Sharp diamond tips are currently fabricated as individual tips or arrays by three principal methods: (1) focused ion beam milling and gluing onto a cantilever of individual diamond tips, (2) coating silicon tips with diamond films, or (3) molding diamond into grooves etched in a sacrificial substrate, bonding the sacrificial substrate to another substrate or electrodepositing of a handling chip, followed by dissolution of the sacrificial substrate. The first method is tedious and serial in nature but does produce very sharp tips, the second method results in tips whose radius is limited by the thickness of the diamond coating, while the third method involves a costly bonding and release process and difficulties in thoroughly filling the high aspect ratio apex of molding grooves with diamond at the nanoscale. To overcome the difficulties with these existing methods, this article reports on the feasibility of the fabrication of sharp diamond tips by direct etching of ultrananocrystalline diamond (UNCD{reg_sign}) as a starting and structural material. The UNCD is reactive ion etched using a cap-precursor-mask scheme. An optimized etching recipe demonstrates the formation of ultrasharp diamond tips ({approx} 10 nm tip radius) with etch rates of 650 nm/min.

Moldovan, N.; Divan, R.; Zeng, H.; Carlisle, J. A.; Advanced Diamond Tech.

2009-12-07

105

Characterization of single-crystal diamond grown from the vapor phase on substrates of natural diamond  

SciTech Connect

The results of studies of single-crystal diamond layers with orientation (100) grown on substrates of IIa-type natural diamond by chemical-vapor deposition and of semiconductor diamond obtained subsequently by doping by implantation of boron ions are reported. Optimal conditions of postimplantation annealing of diamond that provide the hole mobility of 1150 cm{sup 2} V{sup -1} s{sup -1} (the highest mobility obtained so far for semiconductor diamond after ion implantation) are given.

Altukhov, A. A. [ITC UralAlmazInvest (Russian Federation); Vikharev, A. L.; Gorbachev, A. M. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Dukhnovsky, M. P.; Zemlyakov, V. E. [FSUE Istok (Russian Federation); Ziablyuk, K. N.; Mitenkin, A. V. [ITC UralAlmazInvest (Russian Federation); Muchnikov, A. B., E-mail: mabl@appl.sci-nnov.ru; Radishev, D. B. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Ratnikova, A. K.; Fedorov, Yu. Yu. [FSUE Istok (Russian Federation)

2011-03-15

106

Industrial diamond  

USGS Publications Warehouse

Estimated 2011 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2011, natural industrial diamonds were produced in more than 20 countries, and synthetic industrial diamond was produced in at least 13 countries. About 98 percent of the combined natural and synthetic global output was produced in China, Ireland, Japan, Russia, South Africa and the United States. China is the world's leading producer of synthetic industrial diamond followed by Russia and the United States.

Olson, D.W.

2012-01-01

107

Industrial diamond  

USGS Publications Warehouse

Estimated world production of natural and synthetic industrial diamond was about 4.44 billion carats in 2010. Natural industrial diamond deposits have been found in more than 35 countries, and synthetic industrial diamond is produced in at least 15 countries.

Olson, D.W.

2011-01-01

108

Industrial diamond  

USGS Publications Warehouse

Estimated 2012 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2012, natural industrial diamonds were produced in at least 20 countries, and synthetic industrial diamond was produced in at least 12 countries. About 99 percent of the combined natural and synthetic global output was produced in Belarus, China, Ireland, Japan, Russia, South Africa and the United States. During 2012, China was the world’s leading producer of synthetic industrial diamond followed by the United States and Russia. In 2012, the two U.S. synthetic producers, one in Pennsylvania and the other in Ohio, had an estimated output of 103 million carats, valued at about $70.6 million. This was an estimated 43.7 million carats of synthetic diamond bort, grit, and dust and powder with a value of $14.5 million combined with an estimated 59.7 million carats of synthetic diamond stone with a value of $56.1 million. Also in 2012, nine U.S. firms manufactured polycrystalline diamond (PCD) from synthetic diamond grit and powder. The United States government does not collect or maintain data for either domestic PCD producers or domestic chemical vapor deposition (CVD) diamond producers for quantity or value of annual production. Current trade and consumption quantity data are not available for PCD or for CVD diamond. For these reasons, PCD and CVD diamond are not included in the industrial diamond quantitative data reported here.

Olson, D.W.

2013-01-01

109

Industrial diamond  

USGS Publications Warehouse

In 2005, estimated world production of natural and synthetic industrial diamond was 630 million carats. Natural industrial diamond deposits were found in more than 35 countries. Synthetic industrial diamond is produced in at least 15 countries. More than 81% of the combined natural and synthetic global output was produced in Ireland, Japan, Russia, South Africa and the United States.

Olson, D.W.

2006-01-01

110

The Design of Diamond Compton Telescope  

E-print Network

We have developed radiation detectors using the new synthetic diamonds. The diamond detector has an advantage for observations of "low/medium" energy gamma rays as a Compton telescope. The primary advantage of the diamond detector can reduce the photoelectric effect in the low energy range, which is background noise for tracking of the Compton recoil electron. A concept of the Diamond Compton Telescope (DCT) consists of position sensitive layers of diamond-striped detector and calorimeter layer of CdTe detector. The key part of the DCT is diamond-striped detectors with a higher positional resolution and a wider energy range from 10 keV to 10 MeV. However, the diamond-striped detector is under development. We describe the performance of prototype diamond detector and the design of a possible DCT evaluated by Monte Carlo simulations.

Hibino, Kinya; Okuno, Shoji; Yajima, Kaori; Uchihori, Yukio; Kitamura, Hisashi; Takashima, Takeshi; Yokota, Mamoru; Yoshida, Kenji

2007-01-01

111

The Design of Diamond Compton Telescope  

E-print Network

We have developed radiation detectors using the new synthetic diamonds. The diamond detector has an advantage for observations of "low/medium" energy gamma rays as a Compton telescope. The primary advantage of the diamond detector can reduce the photoelectric effect in the low energy range, which is background noise for tracking of the Compton recoil electron. A concept of the Diamond Compton Telescope (DCT) consists of position sensitive layers of diamond-striped detector and calorimeter layer of CdTe detector. The key part of the DCT is diamond-striped detectors with a higher positional resolution and a wider energy range from 10 keV to 10 MeV. However, the diamond-striped detector is under development. We describe the performance of prototype diamond detector and the design of a possible DCT evaluated by Monte Carlo simulations.

Kinya Hibino; Toshisuke Kashiwagi; Shoji Okuno; Kaori Yajima; Yukio Uchihori; Hisashi Kitamura; Takeshi Takashima; Mamoru Yokota; Kenji Yoshida

2007-07-23

112

Industrial diamond  

USGS Publications Warehouse

Part of the 1999 Industrial Minerals Review. A review of the state of the global industrial diamond industry in 1999 is presented. World consumption of industrial diamond has increased annually in recent years, with an estimated 500 million carats valued between $650 million and $800 million consumed in 1999. In 1999, the U.S. was the world's largest market for industrial diamond and was also one of the world's main producers; the others were Ireland, Russia, and South Africa. Uses of industrial diamonds are discussed, and prices of natural and synthetic industrial diamond are reported.

Olson, D.W.

2000-01-01

113

Diamond-like carbon (DLC) thin film bioelectrodes: effect of thermal post-treatments and the use of Ti adhesion layer.  

PubMed

The effect of thermal post-treatments and the use of Ti adhesion layer on the performance of thin film diamond like carbon bioelectrodes (DLC) have been investigated in this work. The following results were obtained: (i) The microstructure of the DLC layer after the deposition was amorphous and thermal annealing had no marked effect on the structure, (ii) formation of oxygen containing SiOx and Ti[O,C] layers were detected at the Si/Ti and Ti/DLC interfaces with the help of transmission electron microscope (TEM), (iii) thermal post-treatments increased the polar fraction of the surface energy, (iv) cyclic voltammetry (CV) measurements showed that the DLC films had wide water windows and were stable in contact with dilute sulphuric acid and phosphate buffered saline (PBS) solutions, (v) use of Ti interlayer between Pt(Ir) microwire and DLC layer was crucial for the electrodes to survive the electrochemical measurements without the loss of adhesion of the DLC layer, (vi) DLC electrodes with small exposed Pt areas were an order of magnitude more sensitive towards dopamine than Pt electrodes and (vii) thermal post-treatments did not markedly change the electrochemical behavior of the electrodes despite the significant increase in the polar nature of the surfaces. It can be concluded that thin DLC bioelectrodes are stable under physiological conditions and can detect dopamine in micro molar range, but their sensitivity must be further improved. PMID:24268281

Laurila, Tomi; Rautiainen, Antti; Sintonen, Sakari; Jiang, Hua; Kaivosoja, Emilia; Koskinen, Jari

2014-01-01

114

Conflict Diamonds  

NSDL National Science Digital Library

New from the United Nations, this short, informative site cautions against conflict diamonds, which are defined as "diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognized governments, and are used to fund military action in opposition to those governments." Along with general descriptions of conflict diamonds, the site briefly explains the ways in which the UN, governments, and non-governmental organizations are trying to halt the sale of these gems, including the drafting of a strict "Certificate of Origin" regime which will certify that only legitimate diamonds reach the market. Conflict Diamonds looks at the UN's anti-conflict diamond activity in two specific countries: Angola and Sierra Leone. For more information on Conflict Diamonds, please see the July 27, 2000 Scout Report for Business and Economics.

115

High-reliability passivation of hydrogen-terminated diamond surface by atomic layer deposition of Al{sub 2}O{sub 3}  

SciTech Connect

Although the two-dimensional hole gas (2DHG) of a hydrogen-terminated diamond surface provides a unique p-type conducting layer for high-performance transistors, the conductivity is highly sensitive to its environment. Therefore, the surface must be passivated to preserve the 2DHG, especially at high temperature. We passivated the surface at high temperature (450?°C) without the loss of C-H surface bonds by atomic layer deposition (ALD) and investigated the thermal reliability of the Al{sub 2}O{sub 3} film. As a result, C-H bonds were preserved, and the hole accumulation effect appeared after the Al{sub 2}O{sub 3} deposition by ALD with H{sub 2}O as an oxidant. The sheet resistivity and hole density were almost constant between room temperature and 500?°C by the passivation with thick Al{sub 2}O{sub 3} film thicker than 38?nm deposited by ALD at 450?°C. After the annealing at 550?°C in air The sheet resistivity and hole density were preserved. These results indicate the possibility of high-temperature application of the C-H surface diamond device in air. In the case of lower deposition temperatures, the sheet resistivity increased after air annealing, suggesting an insufficient protection capability of these films. Given the result of sheet resistivity after annealing, the increase in the sheet resistivity of these samples was not greatly significant. However, bubble like patterns were observed in the Al{sub 2}O{sub 3} films formed from 200 to 400?°C by air annealing at 550?°C for 1 h. On the other hand, the patterns were no longer observed at 450?°C deposition. Thus, this 450?°C deposition is the sole solution to enabling power device application, which requires high reliability at high temperatures.

Daicho, Akira, E-mail: notevayas-tales@ruri.waseda.jp; Saito, Tatsuya; Kurihara, Shinichiro; Kawarada, Hiroshi, E-mail: kawarada@waseda.jp [School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Hiraiwa, Atsushi [Institute for Nanoscience and Nanotechnology, Waseda University, 513 Waseda-tsurumaki, Shinjuku, Tokyo 162-0041 (Japan)

2014-06-14

116

Diamond Electronic Devices  

NASA Astrophysics Data System (ADS)

For high-power and high-voltage applications, silicon is by far the dominant semiconductor material. However, silicon has many limitations, e.g. a relatively low thermal conductivity, electric breakdown occurs at relatively low fields and the bandgap is 1.1 eV which effectively limits operation to temperatures below 175° C. Wide-bandgap materials, such as silicon carbide (SiC), gallium nitride (GaN) and diamond offer the potential to overcome both the temperature and power handling limitations of silicon. Diamond is the most extreme in this class of materials. By the fundamental material properties alone, diamond offers the largest benefits as a semiconductor material for power electronic applications. On the other hand, diamond has a problem with a large carrier activation energy of available dopants which necessitates specialised device concepts to allow room temperature (RT) operation. In addition, the role of common defects on the charge transport properties of diamond is poorly understood. Notwithstanding this, many proof-of-principle two-terminal and three-terminal devices have been made and tested. Two-terminal electronic diamond devices described in the literature include: p-n diodes, p-i-n diodes, various types of radiation detectors, Schottky diodes and photoconductive or electron beam triggered switches. Three terminal devices include e.g. MISFETs and JFETs. However, the development of diamond devices poses great challenges for the future. A particularly interesting way to overcome the doping problem, for which there has been some recent progress, is to make so-called delta doped (or pulse-doped) devices. Such devices utilise very thin (˜1 nm) doped layers in order to achieve high RT activation.

Isberg, J.

2010-11-01

117

Thermal diffusivity of diamond films  

NASA Technical Reports Server (NTRS)

A laser pulse technique to measure the thermal diffusivity of diamond films deposited on a silicon substrate is developed. The effective thermal diffusivity of diamond film on silicon was measured by observing the phase and amplitude of the cyclic thermal waves generated by the laser pulses. An analytical model is developed to calculate the effective in-plane (face-parallel) diffusivity of a two layer system. The model is used to reduce the effective thermal diffusivity of the diamond/silicon sample to a value for the thermal diffusivity and conductivity of the diamond film. Phase and amplitude measurements give similar results. The thermal conductivity of the films is found to be better than that of type 1a natural diamond.

Albin, Sacharia; Winfree, William P.; Crews, B. Scott

1990-01-01

118

CHAIRMAN'S CIRCLE DIAMOND CIRCLE  

E-print Network

CHAIRMAN'S CIRCLE DIAMOND CIRCLE PRESIDENTIAL CIRCLE EXECUTIVE CIRCLE OUR SPONSORS Sponsoring Host Scarff CONFERENCE SPONSORS DIAMOND CIRCLE The Venetian | The Palazzo DIAMOND CIRCLE M Resort Spa Casino

Walker, Lawrence R.

119

Extreme ultraviolet transmission of a synthetic diamond thin film  

NASA Technical Reports Server (NTRS)

Measurements are presented of a thin film of synthetic diamond at various wavelengths in the extreme ultraviolet. The synthetic diamond combines the transmission properties of carbon with the strength, density, and ruggedness of a natural diamond. The Extreme Ultraviolet Transmission (EUV) of a film of the synthetic diamond has shown the existence of a thin surface layer of silicon, probably in the form of silicon carbide, which is not a contaminant layer.

Vallerga, John V.; Gibson, J. L.; Knowles, J. L.

1991-01-01

120

Diamond Coatings  

NASA Technical Reports Server (NTRS)

Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

1990-01-01

121

Industrial diamond  

USGS Publications Warehouse

World production of natural and synthetic industrial diamond was about 648 million carats in 2006, with 79 percent of the production coming from Ireland, Japan, Russia, South Africa, and the U.S. U.S. consumption was was an estimated 602 million carats, imports were over 391 million carats, and exports were about 83 million carats. About 87 percent of the industrial diamonds market uses synthetic diamonds, which are expected to become less expensive as technology improves and competition from low-cost producers increases.

Olson, D.W.

2007-01-01

122

Industrial diamond  

USGS Publications Warehouse

Part of the 2003 industrial minerals review. Supply and demand data for industrial diamond are provided. Topics discussed are consumption, prices, imports and exports, government stockpiles, and the outlook for 2004.

Olson, D.W.

2004-01-01

123

Diamond nanophotonics  

PubMed Central

Summary We demonstrate the coupling of single color centers in diamond to plasmonic and dielectric photonic structures to realize novel nanophotonic devices. Nanometer spatial control in the creation of single color centers in diamond is achieved by implantation of nitrogen atoms through high-aspect-ratio channels in a mica mask. Enhanced broadband single-photon emission is demonstrated by coupling nitrogen–vacancy centers to plasmonic resonators, such as metallic nanoantennas. Improved photon-collection efficiency and directed emission is demonstrated by solid immersion lenses and micropillar cavities. Thereafter, the coupling of diamond nanocrystals to the guided modes of micropillar resonators is discussed along with experimental results. Finally, we present a gas-phase-doping approach to incorporate color centers based on nickel and tungsten, in situ into diamond using microwave-plasma-enhanced chemical vapor deposition. The fabrication of silicon–vacancy centers in nanodiamonds by microwave-plasma-enhanced chemical vapor deposition is discussed in addition. PMID:23365803

Beha, Katja; Wolfer, Marco; Becker, Merle C; Siyushev, Petr; Jamali, Mohammad; Batalov, Anton; Hinz, Christopher; Hees, Jakob; Kirste, Lutz; Obloh, Harald; Gheeraert, Etienne; Naydenov, Boris; Jakobi, Ingmar; Dolde, Florian; Pezzagna, Sébastien; Twittchen, Daniel; Markham, Matthew; Dregely, Daniel; Giessen, Harald; Meijer, Jan; Jelezko, Fedor; Nebel, Christoph E; Bratschitsch, Rudolf; Leitenstorfer, Alfred; Wrachtrup, Jörg

2012-01-01

124

Nanocrystalline diamond for medicine  

NASA Astrophysics Data System (ADS)

The unique properties of thin amorphous diamond layers make them perspective candidates for producing advanced micro- electronic devices, coatings for cutting tools and optics. Moreover, due to the highest bicompatibility of carbon resulting from the presence of this element in human body, it appears to be a potential biomaterial. Until present the amorphous diamond has found industrial applications in some areas. One of the applications of the carbon layers are coatings for medical implants. The studies of carbon films as coatings for implants in surgery were aimed on the investigations of biological resistance of implants, histopathological investigations on laboratory animals, tests of corrosion resistance, measurements of mechanical properties and a breakdown test in Tyrod solution. The current state of published work in the subject is reviewed in the paper together with a discussion concerning classification of this material.

Mitura, Stanislaw

1997-06-01

125

Diamond fiber field emitters  

DOEpatents

A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

Blanchet-Fincher, Graciela B. (Wilmington, DE); Coates, Don M. (Santa Fe, NM); Devlin, David J. (Los Alamos, NM); Eaton, David F. (Wilmington, DE); Silzars, Aris K. (Landenburg, PA); Valone, Steven M. (Santa Fe, NM)

1996-01-01

126

Multi-layer haemocompatible diamond-like carbon coatings obtained by combined radio frequency plasma enhanced chemical vapor deposition and magnetron sputtering.  

PubMed

Radio-frequency Plasma Enhanced Chemical Vapour Deposition (in different methane dilutions) was used to synthesize adherent and haemocompatible diamond-like carbon (DLC) films on medical grade titanium substrates. The improvement of the adherence has been achieved by interposing a functional buffer layer with graded composition TixTiC1-x (x = 0-1) synthesized by magnetron co-sputtering. Bonding strength values of up to ~67 MPa have been measured by pull-out tests. Films with different sp(3)/sp(2) ratio have been obtained by changing the methane concentration in the deposition chamber. Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed for the physical-chemical characterization of the samples. The highest concentration of sp(3)-C (~87 %), corresponding to a lower DLC surface energy (28.7 mJ/m(2) ), was deposited in a pure methane atmosphere. The biological response of the DLC films was assayed by a state-of-the-art biological analysis method (surface enhanced laser desorption/ionization-time of flight mass spectroscopy), in conjunction with other dedicated testing techniques: Western blot and partial thromboplastin time. The data support a cause-effect relationship between sp(3)-C content, surface energy and coagulation time, as well as between platelet-surface adherence properties and protein adsorption profiles. PMID:23943017

Popa, A C; Stan, G E; Husanu, M A; Pasuk, I; Popescu, I D; Popescu, A C; Mihailescu, I N

2013-12-01

127

A novel radial anode layer ion source for inner wall pipe coating and materials modification--hydrogenated diamond-like carbon coatings from butane gas.  

PubMed

We report a new ion source development for inner wall pipe coating and materials modification. The ion source deposits coatings simultaneously in a 360° radial geometry and can be used to coat inner walls of pipelines by simply moving the ion source in the pipe. Rotating parts are not required, making the source ideal for rough environments and minimizing maintenance and replacements of parts. First results are reported for diamond-like carbon (DLC) coatings on Si and stainless steel substrates deposited using a novel 360° ion source design. The ion source operates with permanent magnets and uses a single power supply for the anode voltage and ion acceleration up to 10 kV. Butane (C4H10) gas is used to coat the inner wall of pipes with smooth and homogeneous DLC coatings with thicknesses up to 5 ?m in a short time using a deposition rate of 70 ± 10 nm min(-1). Rutherford backscattering spectrometry results showed that DLC coatings contain hydrogen up to 30 ± 3% indicating deposition of hydrogenated DLC (a-C:H) coatings. Coatings with good adhesion are achieved when using a multiple energy implantation regime. Raman spectroscopy results suggest slightly larger disordered DLC layers when using low ion energy, indicating higher sp(3) bonds in DLC coatings. The results show that commercially interesting coatings can be achieved in short time. PMID:25173323

Murmu, Peter P; Markwitz, Andreas; Suschke, Konrad; Futter, John

2014-08-01

128

Advanced Diamond Anvil Techniques (Customized Diamond Anvils)  

SciTech Connect

A complete set of diamond-based fabrication tools now exists for making a wide range of different types of diamond anvils which are tailored for various high-P applications. Current tools include: CVD diamond deposition (making diamond); Diamond polishing, laser drilling, plasma etching (removal of diamond); and Lithography, 3D laser pantography (patterning features onto diamond); - Metal deposition (putting electrical circuits and metal masks onto diamond). Current applications include the following: Electrical Conductivity; Magnetic Susceptibility; and High-P/High-T. Future applications may include: NMR; Hall Effect; de Haas - Shubnikov (Fermi surface topology); Calorimetry; and thermal conductivity.

Weir, S

2009-02-11

129

High-density fluids and the growth of monocrystalline diamonds  

NASA Astrophysics Data System (ADS)

The chemical nature and composition of the growth medium of monocrystalline (MC) diamonds is still a matter of debate, partially because carbonate-bearing high-density fluids (HDFs) that are common in fibrous diamonds have not been found in MC diamonds. Here we report the first finding of HDF microinclusions in a MC octahedral diamond from Finsch, South Africa and in the MC octahedral core of a coated diamond from Kankan, Guinea; both diamonds carry nitrogen in B-centers. Numerous microinclusions in diamond Finsch_2a_cap1 are restricted to two thin layers parallel to the (1 1 1) face, ?20 and 200 ?m from the diamond rim. Low-Mg carbonatitic HDFs are found along the inner layer while the outer layer trapped saline compositions. The major and trace element compositions of the inclusions and their infrared spectra are highly similar to those of microinclusions found in fibrous diamonds. A few isolated microinclusions of saline compositions are scattered around a sulfide inclusion in the center of the octahedral core of diamond ON-KAN-383. This evidence for the involvement of oxidized fluids in the formation of MC diamonds adds to previous reports on the antiquity of HDFs in fibrous diamonds, the presence of carbonate and halide phases in inclusions in MC diamonds and the similarity of trace element pattern of a MC diamond to those of low-Mg carbonatitic HDF in fibrous diamonds. In addition, we show that the interaction of HDFs with depleted garnets can produce sinusoidal REE patterns which are one of the primary features of lherzolitic and harzburgitic garnet inclusions in MC diamonds. Together, these observations suggest that HDFs are involved in the formation of many types of diamonds from the Archaean to the Phanerozoic. HDFs are trapped in large quantities during rapid, fibrous growth, but must also be present during the growth of many MC diamonds.

Weiss, Y.; Kiflawi, I.; Davies, N.; Navon, O.

2014-09-01

130

'Diamond' in 3-D  

NASA Technical Reports Server (NTRS)

This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

The image mosaic is about 6 centimeters (2.4 inches) across.

2004-01-01

131

Superconducting nanowire single photon detector on diamond  

SciTech Connect

Superconducting nanowire single photon detectors are fabricated directly on diamond substrates and their optical and electrical properties are characterized. Dark count performance and photon count rates are measured at varying temperatures for 1310?nm and 632?nm photons. A multi-step diamond surface polishing procedure is reported, involving iterative reactive ion etching and mechanical polishing to create a suitable diamond surface for the deposition and patterning of thin film superconducting layers. Using this approach, diamond substrates with less than 300?pm Root Mean Square surface roughness are obtained.

Atikian, Haig A.; Burek, Michael J.; Choy, Jennifer T.; Lon?ar, Marko, E-mail: loncar@seas.harvard.edu [School of Engineering and Applied Sciences, Harvard University, 33 Oxford Street, Cambridge, Massachusetts 02138 (United States); Eftekharian, Amin; Jafari Salim, A.; Hamed Majedi, A. [University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada); Institute for Quantum Computing, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1 (Canada)

2014-03-24

132

Epitaxial growth of europium monoxide on diamond  

SciTech Connect

We report the epitaxial integration of phase-pure EuO on both single-crystal diamond and on epitaxial diamond films grown on silicon utilizing reactive molecular-beam epitaxy. The epitaxial orientation relationship is (001) EuO ? (001) diamond and [110] EuO ?[100] diamond. The EuO layer is nominally unstrained and ferromagnetic with a transition temperature of 68 ± 2 K and a saturation magnetization of 5.5 ± 0.1 Bohr magnetons per europium ion on the single-crystal diamond, and a transition temperature of 67 ± 2 K and a saturation magnetization of 2.1 ± 0.1 Bohr magnetons per europium ion on the epitaxial diamond film.

Melville, A.; Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)] [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mairoser, T.; Schmehl, A. [Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany)] [Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany); Fischer, M.; Gsell, S.; Schreck, M. [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany)] [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany); Awschalom, D. D. [Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637 (United States)] [Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637 (United States); Holländer, B.; Schubert, J. [Peter Grünberg Institute, PGI9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany)] [Peter Grünberg Institute, PGI9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany); Schlom, D. G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States) [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2013-11-25

133

Large-area low-temperature ultrananocrystaline diamond (UNCD) films and integration with CMOS devices for monolithically integrated diamond MEMD/NEMS-CMOS systems.  

SciTech Connect

Because of exceptional mechanical, chemical, and tribological properties, diamond has a great potential to be used as a material for the development of high-performance MEMS and NEMS such as resonators and switches compatible with harsh environments, which involve mechanical motion and intermittent contact. Integration of such MEMS/NEMS devices with complementary metal oxide semiconductor (CMOS) microelectronics will provide a unique platform for CMOS-driven commercial MEMS/NEMS. The main hurdle to achieve diamond-CMOS integration is the relatively high substrate temperatures (600-800 C) required for depositing conventional diamond thin films, which are well above the CMOS operating thermal budget (400 C). Additionally, a materials integration strategy has to be developed to enable diamond-CMOS integration. Ultrananocrystalline diamond (UNCD), a novel material developed in thin film form at Argonne, is currently the only microwave plasma chemical vapor deposition (MPCVD) grown diamond film that can be grown at 400 C, and still retain exceptional mechanical, chemical, and tribological properties comparable to that of single crystal diamond. We have developed a process based on MPCVD to synthesize UNCD films on up to 200 mm in diameter CMOS wafers, which will open new avenues for the fabrication of monolithically integrated CMOS-driven MEMS/NEMS based on UNCD. UNCD films were grown successfully on individual Si-based CMOS chips and on 200 mm CMOS wafers at 400 C in a MPCVD system, using Ar-rich/CH4 gas mixture. The CMOS devices on the wafers were characterized before and after UNCD deposition. All devices were performing to specifications with very small degradation after UNCD deposition and processing. A threshold voltage degradation in the range of 0.08-0.44V and transconductance degradation in the range of 1.5-9% were observed.

Sumant, A.V.; Auciello, O.; Yuan, H.-C; Ma, Z.; Carpick, R. W.; Mancini, D. C.; Univ. of Wisconsin; Univ. of Pennsylvania

2009-05-01

134

Homoepitaxial Boron Doped Diamond Anvil as Heating Element in a Diamond Anvil Cell  

NASA Astrophysics Data System (ADS)

Recent advances in designer-diamond technology have allowed for the use of electrically and thermally conducting homoepitaxially-grown layers of boron-doped diamond (grown at 1200 C with a 2% mixture of CH4 in H, resulting in extremely high doping levels ˜ 10^20/cm^3) to be used as heating elements in a diamond anvil cell (DAC). These diamonds allow for precise control of the temperature inside of the diamond anvil itself, particularly when coupled with a cryostat. Furthermore, the unmatched thermally conducting nature of diamond ensures that no significant spatial gradient in temperature occurs across the culet area. Since a thermocouple can easily be attached anywhere on the diamond surface, we can also measure diamond temperatures directly. With two such heaters, one can raise sample temperatures uniformly, or with any desired gradient along the pressure axis while preserving optical access. In our initial experiments with these diamond anvils we report on the measurement of the thermal conductivity of copper-beryllium using a single diamond heater and two thermocouples. We augment these measurements with measurements of sample pressure via ruby fluorescence and electrical resistance of the sample and diamond heater.

Montgomery, Jeffrey; Samudrala, Gopi; Vohra, Yogesh

2012-02-01

135

Study of diamond film growth and properties  

NASA Technical Reports Server (NTRS)

The objective was to study diamond film growth and its properties in order to enhance the laser damage threshold of substrate materials. Calculations were performed to evaluate laser induced thermal stress parameter, R(sub T) of diamond. It is found that diamond has several orders of magnitude higher in value for R(sub T) compared to other materials. Thus, the laser induced damage threshold (LIDT) of diamond is much higher. Diamond films were grown using a microwave plasma enhanced chemical vapor deposition (MPECVD) system at various conditions of gas composition, pressure, temperature, and substrate materials. A 0.5 percent CH4 in H2 at 20 torr were ideal conditions for growing of high quality diamond films on substrates maintained at 900 C. The diamond films were polycrystalline which were characterized by scanning electron microscopy (SEM) and Raman scattering spectroscopy. The top surface of the growing film is always rough due to the facets of polycrystalline film while the back surface of the film replicates the substrate surface. An analytical model based on two dimensional periodic heat flow was developed to calculate the effective in-plane (face parallel) diffusivity of a two layer system. The effective diffusivity of diamond/silicon samples was measured using a laser pulse technique. The thermal conductivity of the films was measured to be 13.5 W/cm K, which is better than that of a type Ia natural diamond. Laser induced damage experiments were performed on bare Si substrates, diamond film coated Si, and diamond film windows. Significant improvements in the LIDT were obtained for diamond film coated Si compared to the bare Si.

Albin, Sacharial

1990-01-01

136

Design and fabrication of diamond probe for atomic force microscope  

NASA Astrophysics Data System (ADS)

We realized IC-compatible diamond AFM probe technology using our newly developed anodic bonding technique for diamond film to glass together with microfabrication techniques employing CVD diamond film. Using Al film as an intermediate layer, diamond film can be anodically bonded to Pyrex 7740 glass at a bonding temperature of 400-500 degrees C, with an electrostatic voltage of 600V, and a bonding time of 1-2 h in atmosphere. Based on the batch fabrication process proposed here, we demonstrate diamond AFM probes for contact mode measurements consisting of two kind of V-shaped cantilevers integrated with a pyramidal tip. They were optimally designed by FEA, giving spring constants of approximately 1 N/m and 5 N/m. The diamond cantilevers and diamond tips were fabricated by the selective deposition of diamond film and a Si mold technique, respectively. A diamond base, to which the diamond probes have been attached, was then anodically bonded to a glass backing plate to facilitate handling. This bonding technique was found to provide high accuracy and good repeatability. Finally, diamond proves attached with high accuracy to one end of the glass backing plate were obtained by removing the unnecessary Si substrate. They were then successfully mounted in a Si frame by means of four thin diamond brackets, making a chip array in the substrate. These results indicate that this fabrication process would allow the production of large quantities of diamond AFM probes, resulting in a high cost performance.

Shibata, Takayuki; Nakatsuji, Tae; Unno, Kazuya; Makino, Eiji

1999-09-01

137

Diamond films deposited on WC-Co substrates by use of barrier interlayers and nano-grained diamond seeds  

Microsoft Academic Search

Results on the structure, composition and properties of diamond films deposited onto WC-Co cemented carbides via special multilayer barrier interlayers preliminary seeded by nano-grained diamond particles are presented. The barrier interlayers comprise a layer adjacent to the substrate, which completely prevents substrate decarburization and Co diffusion from the substrate, and a diamond-bonding layer needed to obtain an enhanced adhesion of

I. Y. Konyashin; M. B. Guseva; V. G. Babaev; V. V. Khvostov; G. M. Lopez; A. E. Alexenko

1997-01-01

138

The mechanical properties of various chemical vapor deposition diamond structures compared to the ideal single crystal  

NASA Astrophysics Data System (ADS)

The structural and electronic properties of the diamond lattice, leading to its outstanding mechanical properties, are discussed. These include the highest elastic moduli and fracture strength of any known material. Its extreme hardness is strongly connected with the extreme shear modulus, which even exceeds the large bulk modulus, revealing that diamond is more resistant to shear deformation than to volume changes. These unique features protect the ideal diamond lattice also against mechanical failure and fracture. Besides fast heat conduction, the fast vibrational movement of carbon atoms results in an extreme speed of sound and propagation of crack tips with comparable velocity. The ideal mechanical properties are compared with those of real diamond films, plates, and crystals, such as ultrananocrystalline (UNC), nanocrystalline, microcrystalline, and homo- and heteroepitaxial single-crystal chemical vapor deposition (CVD) diamond, produced by metastable synthesis using CVD. Ultrasonic methods have played and continue to play a dominant role in the determination of the linear elastic properties, such as elastic moduli of crystals or the Young's modulus of thin films with substantially varying impurity levels and morphologies. A surprising result of these extensive measurements is that even UNC diamond may approach the extreme Young's modulus of single-crystal diamond under optimized deposition conditions. The physical reasons for why the stiffness often deviates by no more than a factor of two from the ideal value are discussed, keeping in mind the large variety of diamond materials grown by various deposition conditions. Diamond is also known for its extreme hardness and fracture strength, despite its brittle nature. However, even for the best natural and synthetic diamond crystals, the measured critical fracture stress is one to two orders of magnitude smaller than the ideal value obtained by ab initio calculations for the ideal cubic lattice. Currently, fracture is studied mainly by indentation or mechanical breaking of freestanding films, e.g., by bending or bursting. It is very difficult to study the fracture mechanism, discriminating between tensile, shear, and tearing stress components (mode I-III fracture) with these partly semiquantitative methods. A novel ultrasonic laser-based technique using short nonlinear surface acoustic wave pulses, developing shock fronts during propagation, has recently been employed to study mode-resolved fractures of single-crystal silicon. This method allows the generation of finite cracks and the evaluation of the fracture strength for well-defined crystallographic configurations. Laser ultrasonics reaches the critical stress at which real diamond fails and therefore can be employed as a new tool for mechanistic studies of the fracture behavior of CVD diamond in the future.

Hess, Peter

2012-03-01

139

Coatings technology for CVD diamond optics  

NASA Astrophysics Data System (ADS)

CVD diamond optics are now available for far infrared airborne applications in both flat plate and dome geometries. For many applications, these require durable coatings for antireflection and/or oxidation protection. With a high characteristic modulus, diamond may allow the use of relatively weaker materials for such coatings provided that the coatings are well-adhered to the substrate. Single layer and two-layer designs have been assessed based on yttria, ytterbia and silicon. Magnetron sputtered examples have been assessed with single layer coatings reducing single surface reflectivities by 12%, whilst maintaining transmission to 13.5 micrometers . The erosion properties of these coated optics, assessed by water jet impact testing (MIJA), are found to be exceptional, with damage thresholds > 350 ms-1 achieved, with a 0.8 mm jet size. The pre-deposition treatment of the diamond has been found to influence the strength of the diamond/coating interface and thus the durability of the coatings. The nature of the diamond surface and the effects of oxidizing pre-deposition treatments have been investigated by X-ray electron spectroscopy (XPS). Strong oxidizing etches conventionally used to clean diamond can leave the surface rich in chemisorbed oxygen with a range of valence states evident in XPS data. In comparison, the valence states of the carbon atoms at hydrogen terminated surfaces have a much narrower distribution. The type of carbon oxygen bonding on the surface of the diamond is critical to adhesion of transition metal oxide based coatings.

Mollart, Tim P.; Lewis, Keith L.; Wort, Christopher J. H.; Pickles, Charles S. J.

2001-09-01

140

Laser activation of diamond surface for electroless metal plating  

NASA Astrophysics Data System (ADS)

Selective area electroless nickel and copper deposition onto the surface of diamond single crystals and polycrystalline diamond films has been realized. Three methods of laser-assisted activation of diamond surface were applied: (i) prenucleation of diamond surface with a thin layer of palladium catalyst via laser-induced decomposition of a palladium acetyl-acetonate [Pd(acac)2] solid film; (ii) deposition of palladium by means of the decomposition of Pd(acac)2 dissolved in dimethylformamide; (iii) laser-induced damage of diamond surface.

Pimenov, S. M.; Shafeev, G. A.; Laptev, V. A.; Loubnin, E. N.

1994-04-01

141

A Comparison of Mechanical Properties of Three MEMS Materials -Silicon Carbide, Ultrananocrystalline Diamond, and Hydrogen-Free Tetrahedral  

E-print Network

and strength. It has been used in high temperature sensors, micro power applications, and some bioA Comparison of Mechanical Properties of Three MEMS Materials - Silicon Carbide but their scaling was found to be controlled by different specimen size parameters. Therefore, a cross comparison

Espinosa, Horacio D.

142

Plasma spraying method for forming diamond and diamond-like coatings  

DOEpatents

A method and composition is disclosed for the deposition of a thick layer of diamond or diamond-like material. The method includes high temperature processing wherein a selected composition including at least glassy carbon is heated in a direct current plasma arc device to a selected temperature above the softening point, in an inert atmosphere, and is propelled to quickly quenched on a selected substrate. The softened or molten composition crystallizes on the substrate to form a thick deposition layer comprising at least a diamond or diamond-like material. The selected composition includes at least glassy carbon as a primary constituent and may include at least one secondary constituent. Preferably, the secondary constituents are selected from the group consisting of at least diamond powder, boron carbide (B{sub 4}C) powder and mixtures thereof. 9 figs.

Holcombe, C.E.; Seals, R.D.; Price, R.E.

1997-06-03

143

Plasma spraying method for forming diamond and diamond-like coatings  

DOEpatents

A method and composition for the deposition of a thick layer (10) of diamond or diamond-like material. The method includes high temperature processing wherein a selected composition (12) including at least glassy carbon is heated in a direct current plasma arc device to a selected temperature above the softening point, in an inert atmosphere, and is propelled to quickly quenched on a selected substrate (20). The softened or molten composition (18) crystallizes on the substrate (20) to form a thick deposition layer (10) comprising at least a diamond or diamond-like material. The selected composition (12) includes at least glassy carbon as a primary constituent (14) and may include at least one secondary constituent (16). Preferably, the secondary constituents (16) are selected from the group consisting of at least diamond powder, boron carbide (B.sub.4 C) powder and mixtures thereof.

Holcombe, Cressie E. (Farragut, TN); Seals, Roland D. (Oak Ridge, TN); Price, R. Eugene (Knoxville, TN)

1997-01-01

144

Metal diamond semiconductor interface and photodiode application  

NASA Astrophysics Data System (ADS)

Carrier transport mechanism at p-diamond/metal interfaces are studied by analyzing dependencies of specific contact resistance ( ?c) on measurement temperature and acceptor concentration ( NA). A variety of metals, such as Ti, Mo, Cr (carbide-forming metals), Pd, and Co (carbon-soluble metals), are deposited on boron-doped polycrystalline diamond layers, and the ?c values are measured by a transmission line method. Thermal annealing which produces metallurgical reactions between diamond and metal reduces Schottky barrier heights of the contact metals to a constant value. It is found that use of a metal compound which does not react with diamond at elevated temperatures is the key to develop the thermally stable Schottky contact material for p-diamond. Along this guideline, we test the suitability of tungsten carbide (WC) and hafnium nitride (HfN) as thermally stable Schottky contacts to develop a thermally stable, deep-ultraviolet (DUV) photodiode using a boron-doped homoepitaxial p-diamond epilayer. Thermal annealing at 500 °C improves the rectifying current-voltage characteristics of the photodiode, resulting in the excellent thermal stability. The discrimination ratio between DUV and visible light is measured to be as large as 10 6 at a reverse bias voltage as small as 2 V, and it remains almost constant after annealing at 500 °C for 5 h. Metal carbide and nitride contacts for diamond are thus useful for developing a thermally stable diamond DUV photodetector.

Koide, Yasuo

2008-07-01

145

A Ni/surface-modified Diamond Composite Electroplating Coating on Superelastic NiTi Alloy as Potential Dental Bur Design  

E-print Network

adhesion between diamond and metal matrix; on the other hand, superelastic biomedical NiTi alloy was used energy between diamond and general metals and alloys. Diamond particles coated with titanium layer for cutting and abrasion of non-ferrous materials [2,3]. However, diamond is hard to be wetted under

Zheng, Yufeng

146

Effects of high energy Au-ion irradiation on the microstructure of diamond films  

SciTech Connect

The effects of 2.245 GeV Au-ion irradiation and subsequent annealing processes on the evolution of microstructure of diamond films with microcrystalline (MCD) or ultra-nanocrystalline (UNCD) granular structure were investigated, using near edge x-ray absorption fine structure and electron energy loss spectroscopy in transmission electron microscopy. For MCD films, the Au-ion irradiation disintegrated some of the diamond grains, resulting in the formation of nano-sized carbon clusters embedded in a matrix of amorphous carbon (a-C). The annealing process recrystallized the diamond grains and converted the a-C into nano-sized graphite particulates and, at the same time, induced the formation of nano-sized i-carbon clusters, the bcc structured carbon with a{sub 0} = 0.432 nm. In contrast, for UNCD films, the Au-ion irradiation transformed the grain boundary phase into nano-sized graphite, but insignificantly altered the crystallinity of the grains of the UNCD films. The annealing process recrystallized the materials. In some of the regions, the residual a-C phases were transformed into nano-sized graphites, whereas in other regions i-carbon nanoclusters were formed. The difference in irradiation-induced microstructural transformation behavior between the MCD and the UNCD films is ascribed to the different granular structures of the two types of films.

Chen, Shih-Show [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Department of Information Technology and Mobile Communication, Taipei College of Maritime Technology, Tamsui, New-Taipei 251, Taiwan (China); Chen, Huang-Chin [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wang, Wei-Cheng; Lin, I-Nan; Chang, Ching-Lin [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Lee, Chi-Young [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Guo Jinghua [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2013-03-21

147

Molecular Structure of diamond  

NSDL National Science Digital Library

Diamonds were first mined over 4,000 years ago in India. During this period, however, diamonds were of no use as jewelry. Louis de Berqueur, was the first who discovered how to cut facets of a diamond, changing the world of fine jewelry. The diamond is not only found in India but also in South Africa, Brazil, Russia, Austria, and Arkansas. A diamond can be used for several things. The most obvious includes a gemstone for jewelry purposes. It is also used for various industrial functions, such as cutting, grinding, and polishing. These characteristics make the diamond "a girl's best friend."

2002-08-23

148

Direct growth of sub-micron diamond structures  

Microsoft Academic Search

AbstractBy employing optical and electron beam lithography, micrometer and sub-micrometer wide polymer structures were fabricated on a diamond nano-particle layer. After selective removal of the diamond nano-particles (seeds) in the buffer oxide etchant, all samples were exposed to microwave plasma-assisted chemical vapor deposition. Well-defined diamond channels (in widths from 5 ?m down to 250 nm) were realized. The advantages and limitations of

O. Babchenko; E. Verveniotis; K. Hruska; M. Ledinsky; A. Kromka; B. Rezek

149

Fabrication of thin diamond membranes for quantum information processing  

NASA Astrophysics Data System (ADS)

Coupling of nano-photonic devices to color centers in diamond offers exceptional opportunities to enhance our understanding of light-matter interactions. The formation of thin single crystal diamond membranes containing such centers, is an important prerequisite for the fabrication of diamond based devices. However, there are challenges in forming such membranes in ways that do not compromise the quality of the cavities or the optical properties of the emitters. Here we report the formation of optically active diamond membranes and the subsequent fabrication of optical cavities. In our approach, 1.7 ?m thick diamond membranes were generated by forming a sacrificial layer using ion implantation, followed by thermal annealing. These membranes then served as templates for the epitaxial overgrowth of ˜ 300 nm of diamond using CVD. Remarkably, the regrown films reveal the presence of optically active defects which were not present in the template, such as silicon-vacancy (SiV) or nitrogen vacancy centers. Microdisk cavities were then formed from the regrown single crystal diamond membranes. Whispering gallery modes (WGMs) with quality factors of ˜ 3000 were measured from the diamond cavities. Spectral overlap of WGMs with the zero phonon line of SiV centers was observed and lifetime reduction of the coupled emitter -- cavity system was measured. The demonstration of coupling between diamond emitters and a single crystal diamond cavity is a crucial step towards diamond integrated nano-photonic networks.

Aharonovich, Igor; Lee, Jonathan; Magyar, Andrew; Hu, Evelyn

2012-02-01

150

Diamond Sheet: A new diamond tool material  

NASA Technical Reports Server (NTRS)

Diamond sheet is termed a diamond tool material because it is not a cutting tool, but rather a new material from which a variety of different tools may be fabricated. In appearance and properties, it resembles a sheet of copper alloy with diamond abrasive dispersed throughout it. It is capable of being cut, formed, and joined by conventional methods, and subsequently used for cutting as a metal bonded diamond tool. Diamond sheet is normally made with industrial diamond as the abrasive material. The metal matrix in diamond sheet is a medium hard copper alloy which has performed well in most applications. This alloy has the capability of being made harder or softer if specific cutting conditions require it. Other alloys have also been used including a precipitation hardened aluminum alloy with very free cutting characteristics. The material is suitable for use in a variety of cutting, surfacing, and ring type tools, as well as in such mundane items as files and sandpaper. It can also be used as a bearing surface (diamond to diamond) and in wear resistant surfaces.

Mackey, C. R.

1982-01-01

151

'Diamond Jenness': A Tough Grind  

NASA Technical Reports Server (NTRS)

This microscopic imager mosaic of the target area called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

The image mosaic is about 6 centimeters (2.4 inches) across.

2004-01-01

152

'Diamond Jenness': Before the Grind  

NASA Technical Reports Server (NTRS)

This microscopic imager mosaic of the rock called 'Diamond Jenness' was snapped on sol 177 before NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool, or 'Rat.'

Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer. On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

The image mosaic is about 6 centimeters (2.4 inches) across.

2004-01-01

153

'Diamond Jenness': After the Grind  

NASA Technical Reports Server (NTRS)

This microscopic imager mosaic taken by NASA's Mars Exploration Rover Opportunity shows the rock dubbed 'Diamond Jenness.' It was taken on sol 177 (July 23, 2004) after the rover first ground into the rock with its rock abrasion tool, or 'Rat.' The rover later ground into the rock a second time. A sliced spherule, or 'blueberry,' is visible in the upper left corner of the hole.

Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

The image mosaic is about 6 centimeters (2.4 inches) across.

2004-01-01

154

Synthetic diamond in electrochemistry  

Microsoft Academic Search

The results of studies on the electrochemistry of diamond carried out during the last decade are reviewed. Methods for the preparation, the crystalline structure and the main electrophysical properties of diamond thin films are considered. Depending on the doping conditions, the diamond behaves as a superwide-gap semiconductor or as a semimetal. It is shown that the 'metal-like' diamond is corrosion-resistant

Yurii V. Pleskov

1999-01-01

155

Photoinduced graphitization of diamond  

NASA Astrophysics Data System (ADS)

The accumulative regime of diamond graphitization by a sequence of sub-threshold (for single impulse) femtosecond laser pulses has been studied. The model describing accumulative graphitization as gradual growth of graphite centers embedded into a diamond matrix is presented. The experimental data suggest that both the laser heating of these centers and the direct photodamage of the diamond lattice are involved in the process of diamond–graphite transformation.

Kononenko, V. V.; Gololobov, V. M.; Kononenko, T. V.; Konov, V. I.

2015-01-01

156

Composite and diamond cold cathode materials  

SciTech Connect

Cold-cathode technology for Crossed-Field Amplifiers (CFAs) has not changed significantly over the last thirty years. The material typically used for cold cathode CFAs is either platinum (Pt) or beryllium (Be), although numerous other materials with higher secondary electron emission ratios have been tested. Beryllium cathodes display higher secondary emission ratios, {approximately} 3.4, than Pt, but require a partial pressure of oxygen to maintain a beryllium oxide (BeO) surface layer. These dispensers limit the life of the CFA, both directly, due to oxygen-source filament burnout, and indirectly, by the production of undesirable gases which adversely affect the performance of the CFA. In an attempt to reduce or eliminate the required oxygen dispenser output level, cathodes were constructed from three varieties of Be/BeO composite material and tested in L-4808s, standard forward-wave AEGIS CFAs. Diamond and diamond-like carbons are desirable as cathode materials because of their extremely high secondary electron emission ratio, greater than 20, but their use has previously been prohibitive because of cost, available, and physical characteristics. Because of recent advances in diamond growth technology it is now possible to deposit thin layers of diamond on a variety of geometric objects. In coordination with Penn State University four annular diamond emitters have been fabricated. The diamond emitters will be tested in a standard AEGIS CFA, both under vacuum and with a partial pressure of hydrogen.

Worthington, M.S.; Wheeland, C.L.; Ramacher, K.; Doyle, E. [Litton Systems Inc., Williamsport, PA (United States). Electron Devices Div.

1996-12-31

157

Diamond coated cutting tools for machining of non-ferrous metals and fibre reinforced polymers  

Microsoft Academic Search

Diamond coated cutting tools made their entry into the market already 15 years ago. In the beginning the possible application were limited to machining of graphite and hard polymers, due to the weak adhesion of the diamond coating onto the hardmetal substrates. Intensive theoretical and experimental efforts finally resulted in a significantly increased adhesion of the diamond layers. This development

Arno Köpf; Stefan Feistritzer; Klaus Udier

2006-01-01

158

Zr/oxidized diamond interface for high power Schottky diodes A. Traore,1,2,a)  

E-print Network

Zr/oxidized diamond interface for high power Schottky diodes A. Traore,1,2,a) P. Muret,1,2 A. Fiori larger than 7.7 MV/cm for diamond diodes with a pseudo-vertical architecture, are demonstrated. The power doped diamond layer on a heavily boron doped one, epitaxially grown on a Ib substrate. The origin

Paris-Sud XI, Université de

159

Minimal graphene thickness for wear protection of diamond  

NASA Astrophysics Data System (ADS)

We show, by means of molecular dynamics simulations, that the transformation from diamond to amorphous carbon occurring while sliding under pressure can be prevented by having at least two graphene layers between the diamond slabs. The resulting reduction of wear makes this combination of materials suitable for new coatings and micro- and nanoelectromechanical devices. Grain boundaries, vacancies and steps on the diamond surface do not change this prediction. We attribute this behavior to the bonding in layered materials like graphene. The strong in-plane bonding and the weak interlayer interaction that evolves to a strong interlayer repulsion under pressure prevent the transition to amorphous carbon when more than one layer is present.

van Wijk, M. M.; Fasolino, A.

2015-01-01

160

Voltammetric and impedance behaviours of surface-treated nano-crystalline diamond film electrodes  

NASA Astrophysics Data System (ADS)

The electrochemical performances of hydrogen- and oxygen-terminated nano-crystalline diamond film electrodes were investigated by cyclic voltammetry and AC impedance spectroscopy. In addition, the surface morphologies, phase structures, and chemical states of the two diamond films were analysed by scanning probe microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The results indicated that the potential window is narrower for the hydrogen-terminated nano-crystalline diamond film than for the oxygen-terminated one. The diamond film resistance and capacitance of oxygen-terminated diamond film are much larger than those of the hydrogen-terminated diamond film, and the polarization resistances and double-layer capacitance corresponding to oxygen-terminated diamond film are both one order of magnitude larger than those corresponding to the hydrogen-terminated diamond film. The electrochemical behaviours of the two diamond film electrodes are discussed.

Liu, F. B.; Jing, B.; Cui, Y.; Di, J. J.; Qu, M.

2015-04-01

161

Electronic properties of graphene-single crystal diamond heterostructures  

SciTech Connect

Single crystal diamond has been used as a substrate to support single layer graphene grown by chemical vapor deposition methods. It is possible to chemically functionalise the diamond surface, and in the present case H-, F-, O-, and N-group have been purposefully added prior to graphene deposition. The electronic properties of the resultant heterostructures vary strongly; a p-type layer with good mobility and a band gap of ?0.7?eV is created when H-terminated diamond layers are used, whilst a layer with more metallic-like character (high carrier density and low carrier mobility) arises when N(O)-terminations are introduced. Since it is relatively easy to pattern these functional groups on the diamond surface, this suggests that this approach may offer an exciting route to 2D device structures on single layer graphene sheets.

Zhao, Fang; Thuong Nguyen, Thuong; Golsharifi, Mohammad; Amakubo, Suguru; Jackman, Richard B., E-mail: r.jackman@ucl.ac.uk [London Centre for Nanotechnology and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Loh, K. P. [Department of Chemistry, National University of Singapore, 3 Science Drive, Singapore 117543 (Singapore)

2013-08-07

162

Ultrahydrophobicity of ZnO modified CVD diamond films  

NASA Astrophysics Data System (ADS)

Chemical vapor deposited (CVD) polycrystalline diamond films with an ultrahydrophobic surface were fabricated by constructing a hierarchical structure through sputtering a ZnO layer on diamond grains, with a growth step feature. Under optimized conditions, the combined original diamond with a step structure of the ZnO can achieve a water contact angle (WCA) of as high as 141° ± 1°. It is proved that WCA decreases as the roughness of ZnO/PDF reduced. It can be concluded that the step structure of diamond grains and ZnO nuclei size have a great influence on the variation of WCA.

Yang, YiZhou; Wang, ChuanXi; Li, HongDong; Lin, Quan

2013-04-01

163

Diamond/aluminium nitride composites for efficient thermal management applications  

SciTech Connect

Synthetic diamond/AlN composite materials have been fabricated by a combination of microwave plasma-assisted chemical vapor deposition and molecular beam epitaxy. These wide band gap semiconductor heterojunctions show promises for many applications, including thermal management, deep ultraviolet light emitting devices, and high power and high temperature electronics. Here, we report results of an interface study of polycrystalline diamond layers grown on single crystal AlN(0001). High resolution transmission microscopy revealed atomically sharp interfaces between diamond and AlN. Temperature dependent Raman spectroscopy measurements showed reduced thermal resistance on diamond-coated AlN substrates compared to uncoated AlN at temperatures above 330 K.

Cervenka, J.; Dontschuk, N.; Prawer, S. [School of Physics, University of Melbourne, VIC (Australia); Ladouceur, F. [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW (Australia); Duvall, S. G. [Silanna Semiconductor Pty Ltd., Sydney, NSW (Australia)

2012-07-30

164

Diamonds for beam instrumentation  

SciTech Connect

Diamond is perhaps the most versatile, efficient and radiation tolerant material available for use in beam detectors with a correspondingly wide range of applications in beam instrumentation. Numerous practical applications have demonstrated and exploited the sensitivity of diamond to charged particles, photons and neutrons. In this paper, a brief description of a generic diamond detector is given and the interaction of the CVD diamond detector material with protons, electrons, photons and neutrons is presented. Latest results of the interaction of sCVD diamond with 14 MeV mono-energetic neutrons are shown.

Griesmayer, Erich [CIVIDEC Instrumentation GmbH Schottengasse 3A/1/41, A-1010 Vienna (Austria)

2013-04-19

165

Diamond and Polycrystalline Diamond for MEMS Applications: Simulations and Experiments  

E-print Network

Diamond and Polycrystalline Diamond for MEMS Applications: Simulations and Experiments Tahir C¸ a on Silicon and polycrystalline diamond show that this rapid wear is caused by a variety of factors, related processes on diamond surfaces. We studied the atomic friction of diamond (100)­surface employing an extended

Ã?agin, Tahir

166

Diamond tool machining of materials which react with diamond  

DOEpatents

Apparatus for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond.

Lundin, Ralph L. (Los Alamos, NM); Stewart, Delbert D. (Los Alamos, NM); Evans, Christopher J. (Gaithersburg, MD)

1992-01-01

167

Diamond tool machining of materials which react with diamond  

DOEpatents

An apparatus is described for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond. 1 figs.

Lundin, R.L.; Stewart, D.D.; Evans, C.J.

1992-04-14

168

Handbook of Industrial Diamonds and Diamond Films  

E-print Network

by A T Collins, dedicated to the band structure of diamonds. The article touches a broader range of questions than the contents suggest, since as well as the experimental data, on the basis of which a reliable picture and interpretation of the band structure of diamonds in constructed, it also considers the energy spectra of basic point defects (vacancies) and two electrically active dopants (boron and nitrogen). The contents of the article are largely based on the results of earlier works compiled in Ref. [1], to which have been added the results from the use of synchrotron radiation to find the optical constants for photon energies h# 510 eV (Logofetidis, 1992). Surprisingly, there is no reference to the well-known theoretical calculations carried out by Bernholz and his colleagues in recent years. The following review, by P Klausing, covers the morphology of diamond monocrystals grown using the main contemporary methods, natural diamonds, and crystals (grai

Eds Prelas Popovici; M Prelas; G Popovici; L K Bigelow

169

Growth of single-crystal diamonds in microwave plasma  

NASA Astrophysics Data System (ADS)

A microwave plasma (2.45 GHz) was used for depositing single crystal diamond layers at the deposition rate up to 40 ?m/h in hydrogen-methane mixtures on the substrates from natural and synthetic diamond with the (100) deposition surface and with the size up to 5 × 5 mm. The structure and the defect-impurity composition of the fabricated single crystals with the thickness up to 600 ?m have been investigated using Raman spectroscopy, photoluminescence spectroscopy, cathode luminescence spectroscopy, and electron and optical microscopy. A high quality and purity of the diamond layers deposited from a plasma was confirmed.

Bolshakov, A. P.; Ralchenko, V. G.; Polskiy, A. V.; Konov, V. I.; Ashkinazi, E. E.; Khomich, A. A.; Sharonov, G. V.; Khmelnitsky, R. A.; Zavedeev, E. V.; Khomich, A. V.; Sovyk, D. N.

2012-12-01

170

Ohmic Contact Formation for N-Type Diamond by Selective Doping  

NASA Astrophysics Data System (ADS)

Ohmic contacts with low contact resistivity were formed on phosphorus-doped n-type {111} diamond thin films grown by microwave-plasma chemical-vapor deposition. Heavily-doped diamond layers were selectively grown on a diamond substrate by covering a part of substrate surface with a titanium/gold layer. Gold contacts deposited directory on a lightly phosphorus-doped diamond showed a rectification characteristic, while those formed on the selectively grown, heavily doped diamond layers showed an Ohmic characteristic. The Ohmic property of contacts formed with the heavily doped layers was found to be independent of the metals. It is therefore concluded that the tunneling current dominates carrier transport at the interface between the metal and the heavily doped n-type diamond.

Teraji, Tokuyuki; Katagiri, Masayuki; Koizumi, Satoshi; Ito, Toshimichi; Kanda, Hisao

2003-08-01

171

Diamond anvils with integrated diamond-encapsulated microprobes for high-pressure electrical transport experiments  

SciTech Connect

We have fabricated diamond anvils specially designed for use in ultra-high pressure electrical transport experiments. These anvils, which we refer to as ''designer anvils'', feature thin-film metal microprobes which are encased in a layer of high-quality, epitaxial, chemically vapor deposited (CVD) diamond. The synthetic diamond film ensures that the microprobes are survivable to Mbar pressures, and also serves to electrically insulate the microprobes from the high-pressure gasket. High-pressure resistivity experiments were performed on KI and FeO to pressures of approximately 1.8 and 1.7 Mbars, respectively. Future possible applications of designer anvils are also discussed. [electrical conductivity, synthetic diamond, band overlap, metallization, designer anvils

Akella, J; Catledge, S A; Vohra, Y K; Weir, S

1999-07-21

172

Study on the HPHT synthetic diamond crystal from FeC(H) system and its significance  

Microsoft Academic Search

Investigations of crystal habit, micro-topographic imaging, micro-composition and micro-structural analysis of HPHT synthetic\\u000a diamonds from the Fe-C(H) system indicate that most of them have an octahedral habit. The crystals grow mainly layer-to-layer\\u000a from center to periphery. HPHT synthetic diamond is smaller in size than natural diamond because it only goes through nucleation\\u000a and growth in the early stage. In the

ZhiJun Yang; HongZhong Li; MingSheng Peng; Jun Chen; Feng Lin; YuWei Su

2008-01-01

173

Method for growth of CVD diamond on thin film refractory coatings and glass ceramic materials  

NASA Astrophysics Data System (ADS)

This paper describes a new method for significantly improving diamond film quality and growth rate on insulating substrates and thin films. The usual method of abrading the substrate surface with diamond particles yields good quality CVD diamond films at reasonable deposition rates on semiconducting materials like silicon. However, on insulating materials like fused silica and sapphire, the conventional method of diamond seeding and surface abrasion almost always results in slow growth rates and poor quality films. Current in-house diamond nucleation and growth studies have focused on depositing CVD diamond on substrates such as fused silica, sapphire, and glass ceramics. Diamond was grown successfully on these types of materials using a sacrificial metal layer method called metal induced nucleation of diamond (MIND). This technique offers a way to deposit diamond on glassy materials with improved adhesion and at lower deposition temperatures (less than 650 degree(s)C). In addition, the MIND technique can be used in combination with metal masking and conventional etching to deposit patterns of diamond. The MIND method was combined with another in-house developed technique called sputtered refractory interlayer nucleation technique (SPRINT). Diamond-crystallite size and orientation can be controlled with SPRINT to fabricate low-scatter diamond films. Both techniques are discussed. A reliable, efficient method for growing diamond on insulating materials significantly enhances the feasibility for practical applications of CVD diamond technology. For example, further development of the MIND technique may provide low-scatter, protective diamond films on sapphire and glass ceramics for visible-wavelength windows and missile domes. For electronic applications, reduction in the growth temperature makes CVD diamond more compatible with existing semiconductor processes. The lower growth temperature also helps to alleviate diffusion problems in metal alloys and facilitates the application of diamond coatings to cutting-tool inserts.

Moran, Mark B.; Johnson, Linda F.; Klemm, Karl A.

1994-09-01

174

CHAIRMAN'S CIRCLE DIAMOND CIRCLE  

E-print Network

CHAIRMAN'S CIRCLE DIAMOND CIRCLE PRESIDENTIAL CIRCLE EXECUTIVE CIRCLE OUR SPONSORS CENTER BUSINESS SCHOOL CENTER FOR BUSINESS & ECONOMIC RESEARCH #12;years years years DIAMOND CIRCLE CHAIRMAN'S CIRCLE EXECUTIVE CIRCLE #12;Timing is critical in the ever-changing landscape of commercial real estate

Hemmers, Oliver

175

Diamond Nucleation Using Polyethene  

NASA Technical Reports Server (NTRS)

The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

Morell, Gerardo (Inventor); Makarov, Vladimir (Inventor); Varshney, Deepak (Inventor); Weiner, Brad (Inventor)

2013-01-01

176

Diamond nucleation using polyethene  

DOEpatents

The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

Morell, Gerardo; Makarov, Vladimir; Varshney, Deepak; Weiner, Brad

2013-07-23

177

Optical Absorption of N-Doped Diamond  

E-print Network

Optical Absorption of N- Doped Diamond Presentation by: Winnie H. Liang INT REU: University Diamond Structures · Results · Conclusion #12;Motivation Diamonds... · are fascinating · (natural Colored Diamonds · can be rare and expensive Blue Diamond (Hope Diamond) What about yellow colored diamond

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

178

Layers  

NASA Astrophysics Data System (ADS)

The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states ?4( z), ?5( x), and ?5( y) to the conduction-band state ?1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states ?4( z), ?5( x), and ?5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

Hong, K. J.; Jeong, T. S.; Youn, C. J.

2014-09-01

179

Metal oxynitride and diamond hard coatings for infrared windows  

NASA Astrophysics Data System (ADS)

The protection of IR windows in airborne FLIR sensor systems against erosion resulting from raindrop and particle impact is accomplished by means of a front surface coating. The wavelength ranges required are 8-14 micrometers , where diamond competes with boron phosphide based coatings for the protection of multispectral zinc sulphide used as a window for multiple detectors. This paper describes progress in the development of diamond coatings for germanium windows, including selection and deposition of durable front surface antireflection layers. The diamond layers are deposited by microwave plasma CVD techniques at 500 degrees C. For the multispectral application, hard oxynitride coatings have been developed both as stand-alone coatings and as interlayers for diamond coatings. The multispectral coatings and the antireflection coatings are deposited by a sputtering process, applicable to flats and domes. In both cases, structured surfaces at appropriate scales are used to improve optical transmission and mechanical adhesion.

Miller, Andrew J.; Hudson, Martin D.; Dennis, Paul V.; Wilson, Anthony E. J.

1999-07-01

180

RF Diamond Transistors: Current Status and Future Prospects  

NASA Astrophysics Data System (ADS)

RF diamond transistors have been developed on a hydrogen-terminated surface conductive layer. fT and fmax of 23 and 25 GHz, respectively, have been achieved in a diamond MISFET with a 0.2 ?m gate length. Utilizing de-embedding and small-signal equivalent circuit analysis, parasitic components are extracted. The intrinsic fT and fmax of the 0.2-?m-gate diamond MISFET are estimated to be 26 and 36 GHz, respectively. In this report, some of the challenging steps in device fabrication processes such as the development of a low-resistivity ohmic layer, a high-quality gate insulator and acceptor density control technology, toward high-power and high-frequency diamond transistors with high reliability, are introduced.

Umezawa, Hitoshi; Hirama, Kazuyuki; Arai, Tatsuya; Hata, Hideo; Takayanagi, Hidenori; Koshiba, Toru; Yohara, Keiichiro; Mejima, Soichi; Satoh, Mitsuya; Song, Kwang-Soup; Kawarada, Hiroshi

2005-11-01

181

Surface transfer doping of diamond with a molecular heterojunction  

NASA Astrophysics Data System (ADS)

Surface conductivity and C1s core level measurements were employed to show that surface transfer doping of hydrogen-terminated diamond C(100) can be achieved with a molecular heterojunction formed with C60F48 and an intralayer of zinc-tetraphenylporphyrin. Measurement of the shift in the diamond Fermi energy shows that the zinc-tetraphenylporphyrin (ZnTPP) layer modifies the C60F48-diamond interaction, modulating the extent of charge transfer between the diamond and the fluorofullerene. In contrast to the case of C60F48 acceptors, the presence of a ZnTPP layer prevents the formation of air-induced surface conductivity, showing that the intralayer acts to selectively separate these two doping channels.

Langley, D. P.; Smets, Y.; Stark, C. B.; Edmonds, M. T.; Tadich, A.; Rietwyk, K. J.; Schenk, A.; Wanke, M.; Wu, Q.-H.; Barnard, P. J.; Ley, L.; Pakes, C. I.

2012-01-01

182

Software optimization for electrical conductivity imaging in polycrystalline diamond cutters  

NASA Astrophysics Data System (ADS)

We previously reported on an electrical conductivity imaging instrument developed for measurements on polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. The instrument uses electrical impedance tomography to profile the conductivity in the diamond table. Conductivity images must be acquired quickly, on the order of 5 sec per cutter, to be useful in the manufacturing process. This paper reports on successful efforts to optimize the conductivity reconstruction routine, porting major portions of it to NVIDIA GPUs, including a custom CUDA kernel for Jacobian computation.

Bogdanov, G.; Wiggins, J.; Bertagnolli, K.; Ludwig, R.

2014-02-01

183

Software optimization for electrical conductivity imaging in polycrystalline diamond cutters  

SciTech Connect

We previously reported on an electrical conductivity imaging instrument developed for measurements on polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. The instrument uses electrical impedance tomography to profile the conductivity in the diamond table. Conductivity images must be acquired quickly, on the order of 5 sec per cutter, to be useful in the manufacturing process. This paper reports on successful efforts to optimize the conductivity reconstruction routine, porting major portions of it to NVIDIA GPUs, including a custom CUDA kernel for Jacobian computation.

Bogdanov, G.; Ludwig, R. [Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA 01609 (United States); Wiggins, J.; Bertagnolli, K. [US Synthetic, 1260 South 1600 West, Orem, UT 84058 (United States)

2014-02-18

184

Diamond Schottky barrier diodes  

E-print Network

harder than talc (ranked 1), while corundrum (ranked 9) is only 400 times harder. Diamond cannot be scratched by any other known material, therefore occupies the highest position on Mohs scale. 9 Chapter 2 - Synthetic Single Crystal Diamond en en... cu c "C '"' C'tI J: cu ... ~ '0 en .c ~ 1800 - . - Mohs Scale 1600 10 1 - Talc (1) 2 - Gypsum (2) Diamond-. 1400 3 - Calcite (9) 1200 4 - Fluorite (21) 5 - Apatite (48) 1000 6 - Orthoclase (72) 7 - Quartz (100) 800 8 - Topaz (200...

Brezeanu, Mihai

2008-03-11

185

Diamond and Related Materials, 3 (1994) 783-786 783 Comparison of two models of thin diamond film microhardness data to  

E-print Network

of diamond films (1-3 ~tm thick) on silicon and on a titanium alloy is reported. The measured hardness of the diamond film. Two models were used. The first was an empirical equation determined from finite element for the silicon and titanium alloy substrates respectively. There is a large titanium carbide interfacial layer

Bristol, University of

186

Homoepitaxial {111}-oriented diamond pn junctions grown on B-doped Ib synthetic diamond  

Microsoft Academic Search

Boron- and phosphorus-doped diamond layers were grown successively by microwave plasma-assisted chemical vapour deposition on {111}-oriented boron-doped Ib substrates. The resulting diodes were studied electrically with and without metallization. Although cathodoluminescence results showed that the material quality of the p-type {111} layer could still be improved, Electron Beam Induced Current imaging (EBIC) provided evidence for a space charge region. At

A. Tajani; C. Tavares; M. Wade; C. Baron; E. Gheeraert; E. Bustarret; S. Koizumi; D. Araujo

2004-01-01

187

Diamond Ranch High School.  

ERIC Educational Resources Information Center

Highlights award-winning Diamond Ranch High School (California) that was designed and built on a steep site around Los Angeles considered unsatisfactory for building due to its unstable soils. Building organization is discussed, and photos are provided. (GR)

Betsky, Aaron

2000-01-01

188

Amorphous diamond films  

DOEpatents

Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

Falabella, S.

1998-06-09

189

31 CFR 592.310 - Rough diamond.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Rough diamond. 592.310 Section 592.310 ...DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means...

2013-07-01

190

31 CFR 592.310 - Rough diamond.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Rough diamond. 592.310 Section 592.310 ...DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means...

2012-07-01

191

31 CFR 592.310 - Rough diamond.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Rough diamond. 592.310 Section 592.310 ...DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means...

2014-07-01

192

Simulation of 1550-nm diamond VECSEL with high contrast grating  

NASA Astrophysics Data System (ADS)

In the following paper a simulation of optically pumped vertical external cavity surface emitting lasers (VECSEL) with a novel approach for the improvement of the heat management is presented. In recent VECSEL structures, it was common to use one top diamond heat spreader in order to decrease the thermal resistance of the device by redistributing the heat flow to the lateral regions and thus transporting heat down to the copper heat sink more efficiently. We present here further improvement of the heat management by eliminating the bottom DBR from the heat flow path and substituting it for a diamond with a High Contrast Grating (HCG). Hence the active region, which consists of 5 pairs of AlGaInAs quaternary alloy quantum wells, is sandwiched between two diamond heat spreading layers. The structure of Si HCG deposited on a diamond provides broad wavelength range in which reflectivity is close to 100% for the emitted beam for perpendicular mode polarization with respect to the direction of the HCG trenches. The HCG assures less than 20% reflection and near zero absorption of pumping light, hence it allows for on-axis bottom pumping scheme and integration of the VECSEL with the pumping laser. According to the simulations 300 ?m thick top diamond heat spreader is enough to assure effective heat dissipation mechanism. Replacing the bottom DBR with the diamond heat spreader will provide additional 10% reduction of the thermal impedance. The minimum of thermal impedance is achieved for about 450 ?m thick bottom diamond heat spreader.

Walczak, Jaroslaw; Czyszanowski, Tomasz; Dems, Maciej; Sarzala, Robert P.; Sokol, Adam; Wasiak, Michal; Iakovlev, Vladimir

2012-06-01

193

Heteroepitaxial diamond growth  

NASA Astrophysics Data System (ADS)

Technical highlights from 1993 include the following: Growth Chemistries: A clear correlation was observed between ionization potential of feedstock gasses and critical power necessary for inductive coupling of the plasma and consequent diamond growth. Substrate preparation and epitaxial film quality: Ion-implantation of C and O has been coupled with either electrochemical etching or acid cleaning for surface preparation prior to homoepitaxial growth. Reactor modifications: Key improvements were made to the RF reactor to allow for long growths to consolidate substrates. Liquid mass flow controllers were added to precisely meter both the water and selected alcohol. Ion-implantation and lift off: Lift off of diamond platelets has been achieved with two processes. Ion-implantation of either C or O followed by annealing and implantation of either C or O followed by water based electrolysis. Diamond characterization: Development of novel detect characterization techniques: (1) Etch delineation of defects by exposure to propane torch flame. (2) Hydrogen plasma exposure to enhance secondary electron emission and provide non-topographical defect contrast. Acetylene will react at room temperature with sites created by partial desorption of oxygen from the (100) diamond surface. Thermal desorption measurements give an apparent activation energy for CO desorption from diamond (100) of 45 kcal/mol. Quantum chemical calculations indicate an activation energy of 38 kcal/mol for CO desorption. Ab initio calculations on (100) surfaces indicates that oxygen adsorbed at one dimer site has an effect on the dimerization of an adjacent site.

Markunas, R. J.; Rudder, R. A.; Posthill, J. B.; Thomas, R. E.; Hudson, G.

1994-02-01

194

Partial melting of dry peridotites at high pressures: Determination of compositions of melts segregated from peridotite using aggregates of diamond  

Microsoft Academic Search

The compositions of melts formed by partial melting of two relatively fertile spinel lherzolites were determined at pressures between 10 and 30 kbar under dry conditions using a layer of diamond aggregates sandwiched between peridotite layers. Partial melts segregate and migrate into the pore space between diamond grains soon after their formation. Overgrowth of minerals at quenching modifies the composition

Kei Hirose; Ikuo Kushiro

1993-01-01

195

Au/p-diamond ohmic contacts deposited by RF sputtering  

NASA Astrophysics Data System (ADS)

Ohmic contacts have been formed on diamond films using a monolayer Au. Au film was deposited by radio frequency sputtering. I- V measurements show the good ohmic behavior of the contacts in the as-deposited and annealed states and the specific contact resistivity obtained by circular transmission line model was 1.27 × 10 -3 and 5.43 × 10 -4 ? cm 2, respectively. Radio frequency sputtering makes an obvious interdiffusion between Au and diamond in the as-deposited contacts. Annealing the contact enhances the interdiffusion. X-ray photoelectron spectroscopy analyses and cross-sectional scan electron microscopy reveal the presence of an intermediate layer at the interface due to the intermixing between Au and diamond. Surface native oxide of the diamond film was effectively removed by treating the substrate film in boiling aqua regia solution.

Zhen, C. M.; Wang, X. Q.; Wu, X. C.; Liu, C. X.; Hou, D. L.

2008-12-01

196

Laser Patterning of Diamond. Part II. Surface Nondiamond Carbon Formation and its Removal  

SciTech Connect

As diamond becomes more prevalent for electronic and research applications, methods of patterning diamond will be required. One such method, laser ablation, has been investigated in a related work. We report on the formation of surface nondiamond carbon during laser ablation of both polycrystalline and single-crystal synthetic diamonds. Near edge x-ray absorption fine structure spectroscopy was used to confirm that the nondiamond carbon layer formed during the ablation was amorphous, and Fourier transform infrared absorption spectroscopy (FTIR) was used to estimate the thickness of this layer to be {approx} 60 nm. Ozone cleaning was used to remove the nondiamond carbon layer.

Smedley, J.; Jaye, C; Bohon, J; Rao, T; Fischer, D

2009-01-01

197

Making Diamond in the Laboratory  

ERIC Educational Resources Information Center

Discusses the graphite to diamond transformation and a phase diagram for carbon. Describes high temperature-higher pressure experimental apparatus and growth of diamonds from seed crystals. Reviews properties of the diamond which suggest uses for the synthetic product. Illustrations with text. (GH)

Strong, Herbert

1975-01-01

198

Diamond collecting in northern Colorado.  

USGS Publications Warehouse

The discovery of numerous diamond-bearing kimberlite diatremes in the N Front Range of Colorado and Wyoming is of both scientific and economic interest. Species recovered from heavy-mineral concentrates include Cr-diopside, spinel, Mg-ilmenite, pyrope and diamond. A nodule tentatively identified as a graphite-diamond eclogite was also found. -G.W.R.

Collins, D.S.

1982-01-01

199

CURRICULUM VITAE Howard J. Diamond  

E-print Network

______________________ CURRICULUM VITAE FOR Howard J. Diamond ______________________ NOAA/National Climatic Data Center 1100 Wayne Avenue Silver Spring, Maryland USA 20901 Tel: +1-301-427-2475 Email: howard.diamond@noaa.gov or hjdiamond45@gmail.com #12;Curriculum Vitae Mr. Howard Jeffrey Diamond NOAA/National Climatic Data Center

200

A kinetic model of diamond nucleation and silicon carbide interlayer formation during chemical vapor deposition  

E-print Network

A kinetic model of diamond nucleation and silicon carbide interlayer formation during chemical February 2005 Available online 7 April 2005 Abstract The presence of thin silicon carbide intermediate of carbon atoms into the silicon carbide layer and the morphology and orientation of the diamond film

Dandy, David

201

Impurity impact ionization avalanche in p-type diamond V. Mortet1-3  

E-print Network

acid mixed with potassium nitrate, rinsed in hot DI water and dried with nitrogen. A pair of tungsten temperature. #12;2 The investigation of hot carriers in semiconductor, i.e. carriers subjected to high. The boron doped diamond layer studied in this work was grown on Ib (100) oriented single crystal diamond

Paris-Sud XI, Université de

202

Experimental study of diamond resorption during mantle metasomatism  

NASA Astrophysics Data System (ADS)

Many of kimberlite-derived diamonds are partially dissolved to various degree but show similar resorption style. This resorption style has been observed in experiments with aqueous fluid at the conditions corresponding to kimberlite emplacement (1-2 GPa). At the same time, each diamond population has more than ten percent of diamond crystals with several drastically different resorption styles, which have not been observed in experiments, and may represent partial dissolution of diamonds during metasomatism in different mantle domains. Metasomatic processes modify the composition of subcratonic mantle, may trigger the formation of kimberlite magma, and result in the growth and partial dissolution of diamonds. Composition of metasomatic agents as constrained from studies of the reaction rims on mantle minerals (garnet, clinopyroxene) and experimental studies vary between carbonatitic melt, aqueous silicate melt, and CHO fluid. However, complex chemical pattern of mantle minerals and estimates of redox regime in subcratonic mantle allow different interpretations. Here we explore diamond dissolution morphology as an indicator of the composition of mantle metasomatic agents. Towards this end we examine diamond dissolution morphologies developed in experiments at the conditions of mantle metasomatism in different reacting media and compare them to the mantle-derived dissolution features of natural diamonds. The experiments were conducted in multi-anvil (Walker-Type) apparatus at 6 GPa and 1200-1500oC. Dissolution morphology of natural octahedral diamond crystals (0.5 mg) was examined in various compositions in synthetic system MgO-CaO- SiO2-CO2-H2O. The runs had the following phases present: solid crystals with fluid (various ratio of H2O-CO2-SiO2, and in the air), carbonate melt, carbonate-silicate melt, and carbonate melt with CHO fluid. Experiments produced three different styles of diamond resorption. In the presence of a fluid phase with variable proportions of H2O and CO2 diamond crystals develop ditrigonal outline of {111} faces, striation or hillocks along the edges, and shallow negatively oriented trigonal etch pits with flat or pointed bottom. Presence of SiO2 in the fluid resulted in multi-corner morphology, layering and / or more intensive etching of {111} faces. Dissolution in carbonate melt in the absence of water produced deep stepped-wall hexagonal and trigonal etch pits with negative orientation. The three resorption styles show strong resemblance to the secondary morphology of natural diamonds. This suggests that CHO fluid, aqueous silicate melt, and carbonatatitic melt are metasomatic agents reacting with natural diamonds in subcratonic mantle. The comparison of the experimentally-induced resorption styles to those on natural diamonds show that mantle metasomatism induced by CHO fluid develop morphologies similar to those developed in kimberlite magma. This indicates that significant proportion of kimberlite-hosted diamonds may show resorption features of mantle origin. Aqueous silicate melt induces step-faced multi-corner resorption morphology, similar to natural diamonds with nitrogen aggregation corresponding to eclogitic diamonds. Dissolution in carbonatitic melt results in complex morphologies with deep hexagonal pits similar to natural diamonds with nitrogen data corresponding to peridotitic diamonds.

Fedorchuk, Yana; Schmidt, Max W.; Liebske, Christian

2014-05-01

203

Peculiarities of boron distribution in as-grown boron-doped diamond  

NASA Astrophysics Data System (ADS)

Boron doped diamond (BDD) single crystals have been grown under conditions of high isostatic pressure by the temperature gradient method. Numerous equilateral triangles were found on the fluorescence images of {111}-diamond facets. Structural peculiarities of BDD were investigated by JEM-2010 transmission electron microscope with GIF Quantum attachment for electron energy loss spectroscopy (EELS). High resolution image of diamond lattice revealed some distorted {111}-layers. EELS testifies the presence of boron in distorted regions of diamond lattice. The crystallographic features of BDD and their connection with the superconductivity are discussed.

Blank, V. D.; Kulnitskiy, B. A.; Perezhogin, I. A.; Terentiev, S. A.; Nosukhin, S. A.; Kuznetsov, M. S.

2014-09-01

204

Diamond turned optics  

NASA Astrophysics Data System (ADS)

Diamond turning techniques for high power laser optics were developed during the 70s and 80s as the alternative to conventional polishing of optical surfaces. In principle there are two main areas of applications for diamond tooled high power CO2 laser optics: (1) Aspheric transmissive ZnSe-/Ge-lenses for focussing at very short focal lengths or parabolic Cu- surfaces for laser welding heads. (2) Cu-surfaces for use as extracavity and intracavity beam bending mirrors. In this presentation we concentrate on item two.

Chmelir, Martina; Berger, Manfred R.

1994-08-01

205

Process for making diamonds  

NASA Technical Reports Server (NTRS)

A description is given of a device and process for making industrial diamonds. The device is composed of an exponential horn tapering from a large end to a small end, with a copper plate against the large end. A magnetic hammer abuts the copper plate. The copper plate and magnetic hammer function together to create a shock wave at the large end of the horn. As the wave propagates to the small end, the extreme pressure and temperature caused by the wave transforms the graphite, present in an anvil pocket at the small end, into diamonds.

Rasquin, J. R.; Estes, M. F. (inventors)

1973-01-01

206

Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)  

PubMed Central

In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. and discussed by others [1–3]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H2-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pregrowth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding. PMID:21617759

Fhaner, Mathew; Zhao, Hong; Bian, Xiaochun; Galligan, James J.; Swain, Greg M.

2010-01-01

207

Chemical vapor deposition of diamond thin films on titanium silicon carbide  

NASA Astrophysics Data System (ADS)

Chemical vapor deposition (CVD) has been the main method for synthesizing diamond thin films on hetero substrate materials since 1980s. It has been well acknowledged that both nucleation and growth of diamond on non-diamond surfaces without pre-treatment are very difficult and slow. Furthermore, the weak adhesion between the diamond thin films and substrates has been a major problem for widespread application of diamond thin films. Up to now, Si has been the most frequently used substrate for the study of diamond thin films and various methods, including bias and diamond powder scratching, have been applied to enhance diamond nucleation density. In the present study, nucleation and growth of diamond thin films on Ti3SiC2, a newly developed ceramic-metallic material, using Microwave Plasma Enhanced (MPE) and Hot- Filament (HF) CVD reactors were carried out. In addition, synchrotron-based Near Edge Extended X-Ray Absorption Fine Structure Spectroscopy (NEXAFS) was used to identify the electronic and chemical structures of various NCD films. The results from MPECVD showed that a much higher diamond nucleation density and a much higher film growth rate can be obtained on Ti3SiC2 compared with on Si. Consequently, nanocrystalline diamond (NCD) thin films were feasibly synthesized on Ti3SiC2 under the typical conditions for microcrystalline diamond film synthesis. Furthermore, the diamond films on Ti3SiC 2 exhibited better adhesion than on Si. The early stage growth of diamond thin films on Ti3SiC2 by HFCVD indicated that a nanowhisker-like diamond-graphite composite layer, different from diamond nucleation on Si, initially formed on the surface of Ti3SiC2, which resulted in high diamond nucleation density. These results indicate that Ti3SiC 2 has great potentials to be used both as substrates and interlayers on metals for diamond thin film deposition and application. This research may greatly expand the tribological application of both Ti3SiC 2 and diamond thin films. The results demonstrated that NEXAFS is a reliable and powerful tool to identify NCD films.

Yang, Songlan

2008-10-01

208

Fluidized bed deposition of diamond  

DOEpatents

A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

Laia, Jr., Joseph R. (Los Alamos, NM); Carroll, David W. (Los Alamos, NM); Trkula, Mitchell (Los Alamos, NM); Anderson, Wallace E. (Los Alamos, NM); Valone, Steven M. (Santa Fe, NM)

1998-01-01

209

Nucleation and growth of chemical vapor deposited diamond films  

NASA Astrophysics Data System (ADS)

This research involves a study of the nucleation and growth processes during diamond chemical vapor deposition (CVD) via numerical modeling and simulations. Numerical models have been developed: (1) to examine the chemistry of the intermediate layer that forms at the interface between diamond and non-diamond substrate, (2) to understand the nucleation, size and structure of diamond phase carbon clusters on Si(111) substrates, (3) to study the morphological instabilities associated with diamond growth during chemical vapor deposition. The chemistry of the intermediate layer that develops at the interface between diamond and non-diamond substrate during chemical vapor deposition is analyzed using a thermodynamic quasiequilibrium model. Substrates of Si, Mo, W, Ti, Ta, Fe and Ni are examined, and operating parameters such as the substrate temperature, reactor pressure, and CHsb4:Hsb2 ratio in the gas phase required for the growth of the respective metal carbides/solid carbon are predicted. It is shown that the quasiequilibrium approach is advantageous in that it minimizes the use of kinetics to the degree that rate expressions are obtained without requiring the knowledge of the detailed kinetic models of the processes. A theoretical study of the nucleation, size, and structure of diamond-phase carbon clusters on Si(111) substrates is presented. Silicon is chosen as the non-diamond substrate in this work as it is a common substrate material for diamond deposition. Molecular mechanics analysis has been utilized to predict energetically and entropically feasible pathways for nucleation of carbon clusters. Several mechanistic pathways for nucleation of carbon clusters are examined with Csb2Hsb2 and/or CHsb3 as the nucleation precursors. A possible model for the nucleation mechanism of diamond-phase carbon clusters on beta-SiC(111) surface, which forms epitaxially on Si(111) substrates, is presented. The critical size of the carbon clusters is calculated based on the atomistic theory of nucleation and the proposed nucleation mechanisms. The diamond CVD process has been examined theoretically and the morphological instabilities associated with the growth of diamond films have been investigated with a model based on the continuum species conservation equations coupled to surface reaction kinetics. An analytical model is developed to study the morphological instabilities of the diamond-gas interface during the diamond CVD process based on the linear and nonlinear perturbation theories. Linear stability analysis cannot be used to analyze the evolution of the unstable planar interface to a nonplanar cellular interface. Nonlinear analysis is carried out to study the growth behavior of an interface more accurately over a longer period of time. A two-dimensional numerical model describes the evolution of the gas-solid interface. The numerical and analytical models determine the critical parameters affecting the diamond deposition layer morphology. A dispersive relation is derived which relates the effects of species diffusive transport towards the growing interface, surface diffusion, surface tension, and geometrical factors with the stability of perturbations on the interface. (Abstract shortened by UMI.)

Mahalingam, Pushpa

210

Laser-assisted selective metallisation of diamonds by electroless Ni and Cu plating  

NASA Astrophysics Data System (ADS)

Results are presented on area-selective metallisation of diamond single crystals and CVD diamond films realised by means of electroless metal deposition onto laser-activated diamond surfaces. Two techniques of laser activation of the diamond surface are applied: (1) prenucleation of the surface with a thin layer of Pd catalyst via laser-induced decomposition of a corresponding acetyl-acetonate solid film, and (2) laser-induced damage of the diamond surface. The activated surface is characterised with Auger spectra and X-ray microanalysis techniques. The possible mechanisms of surface activation are discussed along with alternative methods of diamond activation for electroless plating. The adherence strength of the Cu deposit is 1.5-2 N/mm 2.

Shafeev, G. A.; Pimenov, S. M.; Loubnin, E. N.

1995-02-01

211

Diamond-coated tools  

Microsoft Academic Search

Industrial interests have focused on exploiting the special characteristics of diamond coatings as protection for parts which must resist high wear forces or extreme pressures. Such parts are generally fabricated from sintered tungsten carbide. Despite its hardness and toughness, tungsten carbide, even when coated with traditional protective films, does not hold up in certain applications where parts are subjected to

C Faure; W Hänni; C. Julia Schmutz; M Gervanoni

1999-01-01

212

Fracture of synthetic diamond  

SciTech Connect

The fracture behavior of synthetic diamond has been investigated using indentation methods and by the tensile testing of pre-notched fracture-mechanics type samples. Specifically, the fracture toughness of free-standing diamond plates, grown by chemically-vapor deposited (CVD) methods, was measured using Vickers indentations and by the use of disk-shaped compact-tension specimens; the latter method provides an evaluation of the through-thickness fracture properties, whereas the indentation method was performed on the nucleation surface of the sample. Measured fracture toughness ({ital K}{sub c}) values were found to be approximately 5--6 MPa{radical}m by both methods, indicating that the fracture resistance of CVD diamond does not vary appreciably with grain size (within the certainty of the testing procedures). Complications, however, arose with the fracture-mechanics testing regarding crack initiation from a relatively blunt notch; further work is needed to develop pre-cracking methods to permit more reliable fracture toughness testing of diamond. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Drory, M.D. [Crystallume, 3506 Bassett Street, Santa Clara, California 95054 (United States)] [Crystallume, 3506 Bassett Street, Santa Clara, California 95054 (United States); Dauskardt, R.H.; Kant, A.; Ritchie, R.O. [Center for Advanced Materials, Materials Sciences Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)] [Center for Advanced Materials, Materials Sciences Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)

1995-09-01

213

ELECTRON AMPLIFICATION IN DIAMOND.  

SciTech Connect

We report on recent progress toward development of secondary emission ''amplifiers'' for photocathodes. Secondary emission gain of over 300 has been achieved in transmission mode and emission mode for a variety of diamond samples. Techniques of sample preparation, including hydrogenation to achieve negative electron affinity (NEA), have been adapted to this application.

SMEDLEY, J.; BEN-ZVI, I.; BURRILL, A.; CHANG, X.; GRIMES, J.; RAO, T.; SEGALOV, Z.; WU, Q.

2006-07-10

214

Lower pressure synthesis of diamond material  

DOEpatents

Methods of synthesizing a diamond material, particularly nanocrystalline diamond, diamond-like carbon and bucky diamond are provided. In particular embodiments, a composition including a carbon source, such as coal, is subjected to addition of energy, such as high energy reactive milling, producing a milling product enriched in hydrogenated tetrahedral amorphous diamond-like carbon compared to the coal. A milling product is treated with heat, acid and/or base to produce nanocrystalline diamond and/or crystalline diamond-like carbon. Energy is added to produced crystalline diamond-like carbon in particular embodiments to produce bucky diamonds.

Lueking, Angela (State College, PA); Gutierrez, Humberto (State College, PA); Narayanan, Deepa (Redmond, WA); Burgess Clifford, Caroline E. (State College, PA); Jain, Puja (King Of Prussia, PA)

2010-07-13

215

Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings. Chapter 10  

NASA Technical Reports Server (NTRS)

This chapter describes three studies on the surface design, surface engineering, and tribology of chemical-vapor-deposited (CVD) diamond films and coatings toward wear-resistant, self-lubricating diamond films and coatings. Friction mechanisms and solid lubrication mechanisms of CVD diamond are stated. Effects of an amorphous hydrogenated carbon on CVD diamond, an amorphous, nondiamond carbon surface layer formed on CVD diamond by carbon and nitrogen ion implantation, and a materials combination of cubic boron nitride and CVD diamond on the adhesion, friction, and wear behaviors of CVD diamond in ultrahigh vacuum are described. How surface modification and the selected materials couple improved the tribological functionality of coatings, giving low coefficient of friction and good wear resistance, is explained.

Miyoshi, Kazuhisa

1999-01-01

216

Progress on Diamond-Based Cylindrical Dielectric Accelerating Structures  

SciTech Connect

The development of a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high rf breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the waveguide to structure rf coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits. We conclude with a brief overview of the use of diamond microstructures for use in compact rf sources.

Kanareykin, A.; Schoessow, P. [Euclid Techlabs LLC, Solon, OH-44139 (United States); Conde, M.; Gai, W. [High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2006-11-27

217

Thermal diffusivity of diamond films using a laser pulse technique  

NASA Technical Reports Server (NTRS)

Polycrystalline diamond films were deposited using a microwave plasma-enhanced chemical vapor deposition process. A laser pulse technique was developed to measure the thermal diffusivity of diamond films deposited on a silicon substrate. The effective thermal diffusivity of a diamond film on silicon was measured by observing the phase and amplitude of the cyclic thermal waves generated by laser pulses. An analytical model is presented to calculate the effective in-plane (face-parallel) diffusivity of a two-layer system. The model is used to reduce the effective thermal diffusivity of the diamonds/silicon sample to a value for the thermal diffusivity and conductivity of the diamond film. The average effective diffusivity values are 1.47 + or - 0.03 and 1.83 + or - 0.10 yielding thermal diffusivity values of 7.46 + or - 0.90 and 7.33 + or - 0.70 sq cm/s respectively, for the two samples; the calculated thermal con ductivity values are 13.50 and 13.28 W/cmK, which are better than that of type 1a natural diamond. The phase and amplitude measurements give similar results.

Albin, Sacharia; Winfree, William P.; Crews, B. Scott

1990-01-01

218

South Africa, Namibia Diamond Deposits  

NASA Technical Reports Server (NTRS)

This radar image covers a portion of the Richtersveld National Park and Orange River (top of image) in the Northern Cape Province of the Republic of South Africa. The Orange River marks the boundary between South Africa to the south and Namibia to the north. This is an area of active mining for diamonds, which were washed downstream from the famous Kimberley Diamond Area, millions of years ago when the river was much larger. The mining is focused on ancient drainages of the Orange River which are currently buried by think layers of sand and gravel. Scientists are investigating whether these ancient drainages can be seen with the radar's ability to penetrate sand cover in extremely dry regions. A mine, shown in yellow, is on the southern bank of the river in an abandoned bend which is known as an 'oxbow.' The small bright circular areas (left edge of image) west of the mine circles are fields of a large ostrich farm that are being watered with pivot irrigation. The large dark area in the center of the image is the Kubus Pluton, a body of granite rock that broke through the surrounding rocks about 550 million years ago. North is toward the upper right. The area shown is about 55 by 60 kilometers (34 by 37 miles) centered at 28.4 degrees south latitude, 16.8 degrees east longitude. Colors are assigned to different radar frequencies and polarizations as follows: red is L-band horizontally transmitted and horizontally received; green is L-band horizontally transmitted and vertically received; blue is C-band horizontally transmitted and vertically received. The image was acquired on April 18, 1994 by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour. SIR-C/X-SAR is a joint mission of the U.S./German and Italian space agencies.

1998-01-01

219

Diamondization of Graphene and Graphene-BN Bilayers: Chemical Functionalization and Electronic Structure Engineering  

E-print Network

In this article, based on first-principles calculations, we systematically study functionalization induced diamonization of graphene bilayer and graphene-BN hybrid bilayer. With single-side functionalization, the diamondized structures are magnetic semiconductor. Interestingly, if both sides of the bilayer are functionalized, diamondization becomes spontaneous without a barrier. On the other hand, when the bottom layer of the bilayer graphene is replaced by a single hexagonal BN layer, the diamondized structure becomes nonmagnetic metal. The tunable electronic and magnetic properties pave new avenues to construct graphene-based electronics and spintronics devices.

Yuan, Long; Yang, Jinlong; Hou, Jian Guo

2011-01-01

220

High-frequency SAW filters based on diamond films.  

PubMed

We have developed a diamond SAW resonator capable of operating at frequencies over 3 GHz using a SiO(2)/ interdigital transducer (IDT)/AlN/diamond structure. This structure is expected to have a high Q value and a zero temperature coefficient of frequency (TCF) over 3 GHz, based on the high acoustic velocity of AlN. The SAW characteristics of various layered structures composed of SiO(2)/IDT/AlN/diamond substrates were studied both theoretically and experimentally. The SiO(2)/IDT/AlN/diamond substrate structure allows for a thicker IDT metal layer compared with other SAW device designs, such as the SiO(2)/IDT/ZnO/diamond structure. The thicker metal IDT in the present design leads to a lower series resistance and, in turn, a low insertion loss for SAW devices over 3 GHz. Using a second-mode (Sezawa-mode) SAW, the phase velocity and electromechanical coupling coefficient of the SiO(2)/IDT/AlN/diamond substrate reached the larger values of 11 150 m/s and 0.5%, respectively, and a zero TCF characteristic at 25°C was achieved. One-port SAW resonators fabricated from diamond substrates showed a high Q of 660 at 5.4 GHz. The frequency drift over a temperature range of -25°C to 80°C was about 90 ppm, even less than that for ST-quartz SAW substrates. A two-port resonator showed a low insertion loss of 8 dB at 5.4 GHz. Finally, we designed a 5-GHz band-stop SAW filter. A 30-MHz-wide stopband at a -6-dB rejection level was achieved while keeping the passband insertion loss to 0.76 dB. These characteristics of these filters show good potential for SHF-band filters. PMID:23221225

Fujii, Satoshi; Jian, Chunyun

2012-12-01

221

Genetics Home Reference: Diamond-Blackfan anemia  

MedlinePLUS

... literature OMIM Genetic disorder catalog Conditions > Diamond-Blackfan anemia On this page: Description Genetic changes Inheritance Diagnosis ... definitions Reviewed February 2012 What is Diamond-Blackfan anemia? Diamond-Blackfan anemia is a disorder of the ...

222

Fracture of synthetic diamond M. D. Droty  

E-print Network

Fracture of synthetic diamond M. D. Droty Ctystallume, 3506 Bassett Street, Santa Clara, California 1995) The fracture behavior of synthetic diamond has been investigated using indentation methods of synthetic polycrystalline diamond make it a promising material for many structural applications

Ritchie, Robert

223

Diamond Thin Films Handbook David S. Dandy  

E-print Network

1 Diamond Thin Films Handbook Chapter 4 David S. Dandy Department of Chemical Engineering Colorado Sandia National Laboratories Albuquerque, New Mexico 87185 To appear in Diamond Thin Films Handbook J...............................................................................................................................3 II. Gas-phase processes in CVD diamond

Dandy, David

224

Effects of hydrogen atoms on surface conductivity of diamond film  

NASA Astrophysics Data System (ADS)

To investigate the effects of surface chemisorbed hydrogen atoms and hydrogen atoms in the subsurface region of diamond on surface conductivity, models of hydrogen atoms chemisorbed on diamond with (100) orientation and various concentrations of hydrogen atoms in the subsurface layer of the diamond were built. By using the first-principles method based on density functional theory, the equilibrium geometries and densities of states of the models were studied. The results showed that the surface chemisorbed hydrogen alone could not induce high surface conductivity. In addition, isolated hydrogen atoms in the subsurface layer of the diamond prefer to exist at the bond centre site of the C-C bond. However, such a structure would induce deep localized states, which could not improve the surface conductivity. When the hydrogen concentration increases, the C-H-C-H structure and C-3Hbc-C structure in the subsurface region are more stable than other configurations. The former is not beneficial to the increase of the surface conductivity. However, the latter would induce strong surface states near the Fermi level, which would give rise to high surface conductivity. Thus, a high concentration of subsurface hydrogen atoms in diamond would make significant contributions to surface conductivity.

Liu, Fengbin; Cui, Yan; Qu, Min; Di, Jiejian

2015-04-01

225

Low Temperature Growth of Nanostructured Diamond Films on Metals  

NASA Technical Reports Server (NTRS)

The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments performed without the starting nanostructured diamond layer resulted in poorly adhered films with a more crystalline appearance and a higher surface roughness. This low temperature deposition of nanostructured diamond films on metals offers advantages in cases where high residual thermal stress leads to delamination at high temperatures.

Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

2001-01-01

226

The structure of diamond nanoclusters  

Microsoft Academic Search

A model describing the structure of diamond nanoclusters produced by explosive shocks is proposed. The model is based on experimental\\u000a data obtained from x-ray diffraction and small-angle x-ray scattering. This model considers the diamond nanocluster as a crystalline\\u000a diamond core coated by a carbon shell having a fractal structure. The shell structure depends both on the cooling kinetics\\u000a of the

A. E. Aleksenskii; M. V. Baidakova; A. Ya. Vul’; V. I. Siklitskii

1999-01-01

227

Conversion of fullerenes to diamond  

SciTech Connect

A method of forming synthetic diamond on a substrate is disclosed. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond thickness on the substrate.

Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

1993-01-01

228

Conversion of fullerenes to diamond  

SciTech Connect

A method of forming synthetic diamond on a substrate. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond film thickness on the substrate.

Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

1994-01-01

229

Integrated diamond sapphire laser.  

PubMed

We use analytic expressions and simulations to examine a model laser gain element formed by integrating diamond and a solid state laser material, such as, Ti:sapphire. The gain element is designed to provide in a single composite structure the thermal management capabilities of diamond and the optical amplification of the laser material. The model results indicate low temperature and a specific radial dependence of the heat transfer coefficient at the material interfaces are needed to access the highest average powers and highest quality optical fields. We outline paths designed to increase average output power of a lowest order mode laser oscillator based on these gain elements to megawatt levels. The long term goal is economically viable solar power delivered safely from space. The short term goal is a design strategy that will facilitate "proof of principle" demonstrations using currently accessible optical pump and thermal management capabilities. PMID:19471366

Fork, Richard; Walker, Wesley; Laycock, Rustin; Green, Jason; Cole, Spencer

2003-10-01

230

Diamond turning of glass  

SciTech Connect

A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

Blackley, W.S.; Scattergood, R.O.

1988-12-01

231

DIAMOND SECONDARY EMITTER  

SciTech Connect

We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

2005-10-09

232

DIAMOND PEAK WILDERNESS, OREGON.  

USGS Publications Warehouse

No metallic mineral resources were identified during a mineral survey of the Diamond Peak Wilderness in Oregon. Cinder cones within the wilderness contain substantial cinder resources, but similar deposits that are more accessible occur outside the wilderness. The area could have geothermal resources, but available data are insufficient to evaluate their potential. Several deep holes could be drilled in areas of the High Cascades outside the wilderness, from which extrapolations of the geothermal potential of the several Cascade wilderness could be made.

Sherrod, David R.; Moyle, Phillip R.

1984-01-01

233

Ohmic contacts to boron-doped diamond  

NASA Astrophysics Data System (ADS)

Two types of contacts, namely Au and Au/Ta, were fabricated on B-doped diamond films by rf sputtering deposition. I- V measurements show that our Au and Au/Ta contacts have exhibited good ohmic characteristics in their as-deposited states. Upon annealing, their ohmic behaviors were improved to different extent. Compared with Au contact, Au/Ta contact has lower specific contact resistance value and better adhesion. X-ray photoelectron spectroscopy (XPS) analyses indicate that there is an obvious interdiffusion between Au and diamond film in Au contact. The interdiffusion was enhanced by annealing. This interdiffusion layer may be the reason why Au contacts are ohmic in the as-deposited and annealed states. As for Au/Ta contacts, XPS analyses show the formation of TaC at the interface between Ta and diamond film in the as-deposited state, there is an increase of TaC in the annealed contact. The presence of TaC promotes our Au/Ta contacts to have better ohmic characteristic.

Zhen, Congmian; Wang, Yinyue; He, Shanhu; Guo, Qiufen; Yan, Zhijun; Pu, Yuejiao

2003-07-01

234

Surface channel MESFETs on hydrogenated diamond.  

PubMed

Metal–semiconductor field effect transistors (MESFETs) based on hydrogen terminated diamond were fabricated according to different layouts. Aluminum gates were used on single crystal and low-roughness polycrystalline diamond substrates while gold was used for ohmic contacts. Hydrogen terminated layers were deeply investigated by means of Hall bars and transfer length structures. Room temperature Hall and field effect mobility values in excess of 100 cm2 V?¹ s?¹ were measured on commercial and single crystal epitaxial growth (100) plates by using the same hydrogenation process. Hydrogen induced two-dimensional hole gas resulted in sheet resistances essentially stable and repeatable depending on the substrate quality. Self-aligned 400 nm gate length FETs on single crystal substrates showed current density and transconductance values>100 mA mm?¹ and >40 mS mm?¹, respectively. Devices with gate length LG=200 nm showed fMax=26.4 GHz and fT=13.2 GHz whereas those fabricated on polycrystalline diamond, with the same gate geometry, exceeded fMax=23 GHz and fT=7 GHz. This work focused on the optimization of a self-aligned gate structure with respect to the fixed drain-to-source structure with which we observed higher frequency values; the new structure resulted in improvement of DC characteristics, better impedance matching and a reduction in the fMax/fT ratio. PMID:22166514

Conte, G; Giovine, E; Bolshakov, A; Ralchenko, V; Konov, V

2012-01-20

235

Surface channel MESFETs on hydrogenated diamond  

NASA Astrophysics Data System (ADS)

Metal-semiconductor field effect transistors (MESFETs) based on hydrogen terminated diamond were fabricated according to different layouts. Aluminum gates were used on single crystal and low-roughness polycrystalline diamond substrates while gold was used for ohmic contacts. Hydrogen terminated layers were deeply investigated by means of Hall bars and transfer length structures. Room temperature Hall and field effect mobility values in excess of 100 cm2 V-1 s-1 were measured on commercial and single crystal epitaxial growth (100) plates by using the same hydrogenation process. Hydrogen induced two-dimensional hole gas resulted in sheet resistances essentially stable and repeatable depending on the substrate quality. Self-aligned 400 nm gate length FETs on single crystal substrates showed current density and transconductance values >100 mA mm-1 and >40 mS mm-1, respectively. Devices with gate length LG = 200 nm showed fMax = 26.4 GHz and fT = 13.2 GHz whereas those fabricated on polycrystalline diamond, with the same gate geometry, exceeded fMax = 23 GHz and fT = 7 GHz. This work focused on the optimization of a self-aligned gate structure with respect to the fixed drain-to-source structure with which we observed higher frequency values; the new structure resulted in improvement of DC characteristics, better impedance matching and a reduction in the fMax/fT ratio.

Conte, G.; Giovine, E.; Bolshakov, A.; Ralchenko, V.; Konov, V.

2012-01-01

236

Controlled synthesis of diamond and carbon nanotubes on Ni-base alloy  

NASA Astrophysics Data System (ADS)

A Ni-base alloy Inconel 600 has been used as substrate for growing two typical carbon thin film materials, diamond and carbon nanotubes (CNTs), in a hot filament chemical vapor deposition reactor with methane-hydrogen mixture. Under typical deposition conditions, the deposits formed on the as-polished alloy substrate comprise duplex layers, outer diamond layer and intermediate graphite layer. An Al thin film applied as an interlayer on the Inconel alloy effectively prevented the growth of intermediate graphite, and only a dense, adherent diamond film was deposited. When the substrate was negatively biased, a glow discharge was initiated and aligned carbon nanotubes were exclusively synthesized. No diamond was formed in this case.

Li, Y. S.; Hirose, A.

2008-12-01

237

Nanocrystalline tungsten carbide: As incompressible as diamond  

SciTech Connect

We investigate the compressibility of nanocrystalline tungsten carbide (nano-WC) using synchrotron x-ray diffraction. Nano-WC displays a bulk modulus (452 GPa) comparable to that of diamond; it is 10%-15% larger than previously reported values for bulk WC. This finding is consistent with a generalized model of nanocrystal with a compressed surface layer. The linear bulk moduli of nano-WC along a- and c-axes were determined to be 407 and 546 GPa, respectively. First-principles density functional theory (DFT) calculations confirm the experimental observations of an anisotropic linear compressibility and a lower bulk modulus for microsized WC.

Lin, Zhijun; Wang, Lin; Zhang, Jianzhong; Mao, Ho-kwang; Zhao, Yusheng; (CIW); (LANL)

2009-12-10

238

Stable metallization for diamond and other materials  

NASA Technical Reports Server (NTRS)

An adherent and metallurgically stable metallization system for diamond is presented. The big improvement in metallurgical stability is attributed to the use of a ternary, amorphous Ti--Si--N diffusion barrier. No diffusion between the layers and no delamination of the metallization was observed after annealing the schemes at 400.degree. C. for 100 hours and at 900.degree. C. for 30 minutes. Thermal cycling experiments in air from -65 to 155.degree. C. and adhesion tests were performed. Various embodiments are disclosed.

Bachli, Andreas (Inventor); Kolawa, Elzbieta (Inventor); Nicolet, Marc-Aurele (Inventor); Vandersande, Jan W. (Inventor)

2000-01-01

239

Evidence for hexagonal diamond in CVD grown diamond thin films  

NASA Astrophysics Data System (ADS)

Hexagonal diamond, an energetically unfavorable carbon structure, has been of interest, since the first report of its synthesis from crystalline graphite at high pressure and temperature (>=130 kbar and 1000^oC)......^1 The physical properties of this allotrope of carbon are significantly different from those of the cubic diamond. Although, the C-C bonding in both cubic and hexagonal structures is sp^3, the stacking sequences are different. Whereas it is ``ABCABC'' in the commonly observed cubic structure, it is ``ABAB'' in hexagonal diamond. These structures are further characterized by: (i) bond length a = 1.545 å for cubic diamond and a = 2.52 å and c = 4.12 å for hexagonal diamond, (ii) calculated band gaps of 5.6 and 4.5 eV for the cubic and hexagonal structures, respectively, and (iii) relative stability (hexagonal being less stable), hardness (hexagonal is harder than cubic diamond), and different vibrational spectra.....^2 Based on the SEM and Raman spectroscopy data, we present clear evidence for nanometer size (10-100 nm) hexagonal diamond particles in CVD-grown diamond thin films....^3, 4 ^1F. P. Bundy and J. S. Kasper, J. Chem. Phys. 46, 3437 (1967) ^2M. R. Salehpour and S. Satpathy, Phys. Rev. B 41, 3048 (1990) ^3S. C. Sharma et al, J. Mater. Res.5, 2424 (1990)

Chakraborty, Rajarshi; Sharma, Suresh

2010-10-01

240

Influence of diamond surface termination on thermal boundary conductance between Al and diamond  

NASA Astrophysics Data System (ADS)

The effect of diamond surface treatment on the Thermal Boundary Conductance (TBC) between Al and diamond is investigated. The treatments consist in either of the following: exposition to a plasma of pure Ar, Ar:H and Ar:O, and HNO3:H2SO4 acid dip for various times. The surface of diamond after treatment is analyzed by X-ray Photoelectron Spectroscopy, revealing hydrogen termination for the as-received and Ar:H plasma treated samples, pure sp2 termination for Ar treated ones and oxygen (keton-like) termination for the other treatments. At ambient, all the specific treatments improve the TBC between Al and diamond from 23 ± 2 MW m-2 K-1 for the as-received to 65 ± 5, 125 ± 20, 150 ± 20, 180 ± 20 MW m-2 K-1 for the ones treated by Ar:H plasma, acid, pure Ar plasma, and Ar:O plasma with an evaporated Al layer on top, respectively. The effect of these treatments on temperature dependence are also observed and compared with the most common models available in the literature as well as experimental values in the same system. The results obtained show that the values measured for an Ar:O plasma treated diamond with Al sputtered on top stay consistently higher than the values existing in the literature over a temperature range from 78 to 290 K, probably due a lower sample surface roughness. Around ambient, the TBC values measured lay close to or even somewhat above the radiation limit, suggesting that inelastic or electronic processes may influence the transfer of heat at this metal/dielectric interface.

Monachon, Christian; Weber, Ludger

2013-05-01

241

Raman and conductivity studies of boron doped microcrystalline diamond, facetted nanocrystalline diamond and cauliflower diamond films  

NASA Astrophysics Data System (ADS)

We present data showing how the electrical conductivity and Raman spectra of boron-doped CVD diamond films vary with both B content and crystallite size, for microcrystalline diamond (MCD), facetted nanocrystalline diamond (f-NCD) and 'cauliflower' diamond (c-NCD). The position of the Lorentzian contribution to the 500 cm -1 Raman feature was used to estimate the B content. This underestimated the SIMS concentration of B by a factor of ˜5 for the f-NCD and c-NCD films, but remained reasonably accurate for MCD films. One explanation for this is that most of the B incorporates at the grain boundaries and not in substitutional sites.

May, P. W.; Ludlow, W. J.; Hannaway, M.; Heard, P. J.; Smith, J. A.; Rosser, K. N.

2007-09-01

242

Microwave plasma enhanced chemical vapor deposition of nanocrystalline diamond films by bias-enhanced nucleation and bias-enhanced growth  

SciTech Connect

Effects of biasing voltage-current relationship on microwave plasma enhanced chemical vapor deposition of ultrananocrystalline diamond (UNCD) films on (100) silicon in hydrogen diluted methane by bias-enhanced nucleation and bias-enhanced growth processes are reported. Three biasing methods are applied to study their effects on nucleation, growth, and microstructures of deposited UNCD films. Method A employs 320?mA constant biasing current and a negative biasing voltage decreasing from ?490?V to ?375?V for silicon substrates pre-heated to 800?°C. Method B employs 400?mA constant biasing current and a decreasing negative biasing voltage from ?375?V to ?390?V for silicon pre-heated to 900?°C. Method C employs ?350?V constant biasing voltage and an increasing biasing current up to 400?mA for silicon pre-heated to 800?°C. UNCD nanopillars, merged clusters, and dense films with smooth surface morphology are deposited by the biasing methods A, B, and C, respectively. Effects of ion energy and flux controlled by the biasing voltage and current, respectively, on nucleation, growth, microstructures, surface morphologies, and UNCD contents are confirmed by scanning electron microscopy, high-resolution transmission-electron-microscopy, and UV Raman scattering.

Chu, Yueh-Chieh [Institute of Microelectronics, National Cheng Kung University No.1, University Road, Tainan 701, Taiwan (China); Tzeng, Yonhua, E-mail: tzengyo@mail.ncku.edu.tw [Institute of Microelectronics, National Cheng Kung University No.1, University Road, Tainan 701, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University No.1, University Road, Tainan 701, Taiwan (China); Auciello, Orlando [Department of Materials Science and Engineering and Bioengineering, University of Texas in Dallas, 800 W. Campbell Rd, Richardson, Texas 75080 (United States)

2014-01-14

243

Ion beam induced surface graphitization of CVD diamond for x-ray beam position monitor applications  

SciTech Connect

The Advanced Photon Source at ANL is a third-generation synchrotron facility that generates powerful x-ray beams on its undulator beamlines. It is important to know the position and angle of the x- ray beam during experiments. Due to very high heat flux levels, several patented x-ray beam position monitors (XBPM) exploiting chemical vapor deposition (CVD) diamond have been developed. These XBPMs have a thin layer of low-atomic-mass metallic coating so that photoemission from the x rays generate a minute but measurable current for position determination. Graphitization of the CVD diamond surface creates a very thin, intrinsic and conducting layer that can stand much higher temperatures and minimal x-ray transmission losses compared to the coated metallic layers. In this paper, a laboratory sputter ion source was used to transform selected surfaces of a CVD diamond substrate into graphite. The effect of 1-5 keV argon ion bombardment on CVD diamond surfaces at various target temperatures from 200 to 500 C was studied using Auger electron spectroscopy and in-situ electrical resistivity measurements. Graphitization after the ion bombardment has been confirmed and optimum conditions for graphitization studied. Raman spectroscopy was used to identify the overall diamond structure in the bulk of CVD diamond substrate after the ion bombardments. It was found that target temperature plays an important role in stability and electrical conductivity of the irradiated CVD diamonds.

Liu, Chian; Shu, D.; Kuzay, T.M. [Argonne National Lab, IL (United States). Advanced Photon Source; Wen, L.; Melendres, C.A. [Argonne National Lab., IL (United States). Materials Science Div.]|[Argonne National Lab., IL (United States). Chemical Technology Div.

1996-12-31

244

Friction and Wear Properties of As-Deposited and Carbon Ion-Implanted Diamond Films  

NASA Technical Reports Server (NTRS)

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 x 10(exp 17) carbon ions per cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to lO(exp -8) mm(exp 3) N(exp -1) m(exp -1)) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4) mm(exp 7) N(exp -1) m(exp -1)) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, non-diamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7) mm(exp 3) N(exp -1) m(exp-1)). Even in ultrahigh vacuum, the presence of the non-diamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6) mm(exp 3) N(exp -1) m(exp -1). Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum.

Miyoshi, Kazuhisa

1996-01-01

245

‘BLACK DIAMOND’ THORNLESS TRAILING BLACKBERRY  

Technology Transfer Automated Retrieval System (TEKTRAN)

The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), the Oregon Agricultural Experiment Station, and the Washington Agricultural Research Center have released 'Black Diamond', a thornless (botanically “spineless”) blackberry for the processing and fresh market. 'Black Diamond...

246

Interfaces in nano-/microcrystalline multigrade CVD diamond coatings.  

PubMed

The interfaces of multilayered CVD diamond films grown by the hot-filament technique were characterized with high detail using HRTEM, STEM-EDX, and EELS. The results show that at the transition from micro- (MCD) to nanocrystalline diamond (NCD), a thin precursor graphitic film is formed, irrespectively of the NCD gas chemistry used (with or without argon). On the contrary, the transition of the NCD to MCD grade is free of carbon structures other than diamond, the result of a higher substrate temperature and more abundant atomic H in the gas chemistry. At those transitions WC nanoparticles could be found due to contamination from the filament, being also present at the first interface of the MCD layer with the silicon nitride substrate. PMID:24164667

Almeida, Flávia A; Salgueiredo, Ermelinda; Oliveira, Filipe J; Silva, Rui F; Baptista, Daniel L; Peripolli, Suzana B; Achete, Carlos A

2013-11-27

247

Micro CVD diamond heat sink  

NASA Astrophysics Data System (ADS)

Chemical vapor deposition (CVD) diamond film has broad application prospect as heat sink in microelectronic field for its excellent thermal conductivity. The micro CVD diamond heat sinks with the size of 50?m×100?m×2000?m were prepared using mould copy technique. The micro silicon moulds for deposition of micro CVD diamond heat sinks were fabricated using inductivity coupling plasma (ICP) etching process. Micro CVD diamond heat sinks were synthesized under 2% methane and 98% hydrogen by hot filament CVD (HFCVD) method. The micro CVD diamond heat sinks were investigated by SEM, Raman and photo thermal deflection. The results show that favorable micro CVD heat sinks having a thermal conductivity of 960W·m-1·K-1 can be prepared by mould copy technique.

Lu, Wenzhuang; Ai, Guoping; Li, Pin; Sun, Yuli; Zhang, Dan; Zuo, Dunwen

2013-08-01

248

Diamond and Related Materials 8 (1999) 13931401 www.elsevier.com/locate/diamond  

E-print Network

Diamond and Related Materials 8 (1999) 1393­1401 www.elsevier.com/locate/diamond CVD diamond grown Abstract Diamond has been deposited on silicon and molybdenum substrates by microwave plasma enhanced/O ratio around 1:1 was found necessary for diamond to be deposited under our deposition conditions

Tzeng, Yonhua

249

2D photonic crystals fabricated in wide bandgap nanocrystalline diamond  

NASA Astrophysics Data System (ADS)

Chemical vapor deposited (CVD) nanocrystalline diamond films and novel lithography techniques were used to fabricate short wavelength photonic slab crystals (PhC) with feature sizes below 100 nm. CVD diamond was chosen as a promising material for photonic structures due to a large bandgap (5.45 eV) and high index of refraction (2.38). Two methods of fabricating diamond PhC, both based on electron-beam lithography, have been developed. For structures with a high filling coefficient, the best results were obtained with an organic-inorganic bilayer negative resist structure utilizing a polymer-based resist as the bottom layer and a flowable oxide (FOx-12) as the top layer. After E-beam exposure and developing, the FOx pattern was used as a mask for dry etching the bottom resist layer. The resulting structure provides rigid overhang with very fine feature size control that is not affected by the surface roughness of the diamond film. A metal mask was deposited over the patterned bilayer resist followed by lift-off. The remaining metal pattern was used as a protective mask for a highly anisotropic oxygen plasma etch of the nanodiamond film. With the proper choice of the metal mask, this method can be applied to a wide range of materials and feature sizes. Relatively thin nanodiamond structures with a low filling coefficient can be fabricated in a simpler process that utilizes E-beam patterned FOx-12 as an etch mask. Freely suspended PhC slabs were formed by wet etch removal of the sacrificial oxide layer underneath the diamond film. We will present fabrication techniques, experimental data of the mechanical properties of the nanodiamond resonator, and analysis of the optical bandgap of the nanodiamond PhC.

Baldwin, Jeffrey W.; Zalalutdinov, Maxim; Butler, James E.; Feygelson, Tatyana; Houston, Brian H.

2005-11-01

250

Curriculum Vitae Mr. Howard J. Diamond  

E-print Network

Curriculum Vitae Mr. Howard J. Diamond NOAA/National Climatic Data Center 1100 Wayne Avenue, Suite) Fax: +1-301-427-0033 Email: howard.diamond@noaa.gov or h.diamond@auckland.ac.nz Personal Statement: Howard Diamond has worked in various positions within the National Oceanic and Atmospheric Administration

251

Diamond and Related Materials 13 (2004) 270276  

E-print Network

Diamond and Related Materials 13 (2004) 270­276 doi:10.1016/j.diamond.2003.10.076 A new polarised hot filament chemical vapor deposition process for homogeneous diamond nucleation on Si(100) C designed for an intense nucleation and subsequent growth of diamond films on Si(100).Growth process as well

Paris-Sud XI, Université de

252

Integrated AlN/diamond heat spreaders for silicon device processing  

NASA Astrophysics Data System (ADS)

Growth and characterization of AlN and diamond films on the backside of a Si (100) wafer and the integration of AlN/diamond heat spreaders into silicon device technology is investigated. AlN film was deposited by pulsed dc reactive magnetron sputtering at 600 degC and diamond film was deposited by microwave plasma chemical vapor deposition at 900 degC. The films were characterized by x-ray diffraction and transmission electron microscopy for crystalline quality, by scanning electron microscopy for morphology, and by infrared thermography for heat spreading characteristics. The heat spreading characteristics of the silicon wafer with the composite AlN/diamond films were found to be superior to that of wafers with no heat spreaders or to the wafers with either single layer diamond or single layer AlN heat spreaders. Deep level transient spectroscopy and secondary ion mass spectroscopy were performed on the samples with and without the heat spreader to determine the concentration of the impurities that may have been introduced during deposition of AlN or diamond. The results showed that the purity of the wafers is not altered due to the deposition of AlN and diamond and subsequent device processing steps such as high temperature oxidation. The device characteristics were studied by fabrication of Schottky diodes on the wafers with the composite AlN/diamond heat spreader and compared with that of devices on wafers with no heat spreader. The device characteristics were found to be similar and unaffected by integration with an AlN/diamond heat spreader. Integration of AlN/diamond heat spreaders with silicon device processing has been shown to be successful. copyright 2002 American Vacuum Society.

Yoganand, S. N.; Jagannadham, K.; Karoui, A.; Wang, H.

2002-11-01

253

Numerical analysis of Nd:YAG pulsed laser polishing CVD self-standing diamond film  

NASA Astrophysics Data System (ADS)

Chemical vapor deposited (CVD) diamond film has broad application foreground in high-tech fields. But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications. Laser polishing is a useful method to smooth self-standing diamond film. At present, attentions have been focused on experimental research on laser polishing, but the revealing of theoretical model and the forecast of polishing process are vacant. The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory. The experimental investigation is also carried out on Nd:YAG pulsed laser smoothing diamond thick film. The simulation results have good accordance with the results of experimental results. The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd:YAG pulsed laser. The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields. The temperature at the peak of diamond film is much higher than that in the valley, which leads to the smoothing of diamond thick film. The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out. The results show that high power density laser makes the diamond surface rapid heating, evaporation and sublimation after its graphitization. It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle, moderate laser pulsed energy, large repetition rate and moderate laser pulse width. The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality.

Xu, Feng; Hu, Haifeng; Zuo, Dunwen; Xu, Chun; Qing, Zhenghua; Wang, Min

2013-01-01

254

Electron energy loss spectrometry of interstellar diamonds  

NASA Technical Reports Server (NTRS)

The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

1990-01-01

255

Theoretical investigation of the electronic structure and quantum transport in the graphene-C(111) diamond surface system.  

PubMed

We investigate the interaction of a graphene monolayer with the C(111) diamond surface using ab initio density functional theory. To accommodate the lattice mismatch between graphene and diamond, the overlayer deforms into a wavy structure that binds strongly to the diamond substrate. The detached ridges of the wavy graphene overlayer behave electronically as free-standing polyacetylene chains with delocalized ? electrons, separated by regions containing only sp(3) carbon atoms covalently bonded to the (111) diamond surface. We performed quantum transport calculations for different geometries of the system to study how the buckling of the graphene layer and the associated bonding to the diamond substrate affect the transport properties. The system displays high carrier mobility along the ridges and a wide transport gap in the direction normal to the ridges. These intriguing, strongly anisotropic transport properties qualify the hybrid graphene-diamond system as a viable candidate for electronic nanodevices. PMID:24096938

Selli, Daniele; Baburin, Igor; Leoni, Stefano; Zhu, Zhen; Tománek, David; Seifert, Gotthard

2013-10-30

256

Direct coating adherent diamond films on Fe-based alloy substrate: the roles of Al, Cr in enhancing interfacial adhesion and promoting diamond growth.  

PubMed

Direct CVD deposition of dense, continuous, and adherent diamond films on conventional Fe-based alloys has long been considered impossible. The current study demonstrates that such a deposition can be realized on Al, Cr-modified Fe-based alloy substrate (FeAl or FeCrAl). To clarify the fundamental mechanism of Al, Cr in promoting diamond growth and enhancing interfacial adhesion, fine structure and chemical analysis around the diamond film-substrate interface have been comprehensively characterized by transmission electron microscopy. An intermediate graphite layer forms on those Al-free substrates such as pure Fe and FeCr, which significantly deteriorates the interfacial adhesion of diamond. In contrast, such a graphite layer is absent on the FeAl and FeCrAl substrates, whereas a very thin Al-rich amorphous oxide sublayer is always identified between the diamond film and substrate interface. These comparative results indicate that the Al-rich interfacial oxide layer acts as an effective barrier to prevent the formation of graphite phase and consequently enhance diamond growth and adhesion. The adhesion of diamond film formed on FeCrAl is especially superior to that formed on FeAl substrate. This can be further attributed to a synergetic effect including the reduced fraction of Al and the decreased substrate thermal-expansion coefficient on FeCrAl in comparison with FeAl, and a mechanical interlocking effect due to the formation of interfacial chromium carbides. Accordingly, a mechanism model is proposed to account for the different interfacial adhesion of diamond grown on the various Fe-based substrates. PMID:23829602

Li, X J; He, L L; Li, Y S; Yang, Q; Hirose, A

2013-08-14

257

A subpicotesla diamond magnetometer  

E-print Network

Diamond defect centers are promising solid state magnetometers. Single centers allow for high spatial resolution field imaging but are limited in their magnetic field sensitivity to around 10 nT/Hz^(1/2) at room-temperature. Using defect center ensembles sensitivity can be scaled as N^(1/2) when N is the number of defects. In the present work we use an ensemble of 1e11 defect centers for sensing. By carefully eliminating all noise sources like laser intensity fluctuations, microwave amplitude and phase noise we achieve a photon shot noise limited field sensitivity of 0.9 pT/Hz^(1/2) at room-temperature with an effective sensor volume of 8.5e-4 mm^3. The smallest field we measured with our device is 100 fT. While this denotes the best diamond magnetometer sensitivity so far, further improvements using decoupling sequences and material optimization could lead to fT/Hz^(1/2) sensitivity.

Thomas Wolf; Philipp Neumann; Kazuo Nakamura; Hitoshi Sumiya; Junichi Isoya; Jörg Wrachtrup

2014-11-24

258

Nano-diamond film pressure sensor  

Microsoft Academic Search

The edges and corners of nanocrystalline diamond were natural field-emitters. Nano-graphite was mixed in nanocrystalline diamond and cellulose or other organic vehicles to fabricate paste for screen-printed film. The aim of mixed nano-graphite to enhance electric conduction of Nano-diamond film. Through enough ultrasonic disperse the nano-diamond, the paste was screen-printed on the substrates to form Nano- diamond film (NDF). The

Xiuxia Zhang; Wei Shuyi; Erlei Wang; Lixia Zhang; Bingheng Lu

2011-01-01

259

Mechanical properties of different types of diamond  

Microsoft Academic Search

The mechanical properties of different types of diamond (synthetic diamonds with different nitrogen impurity concentrations 0.3 and 200ppm) have been investigated by sclerometry hardness and wear resistance measurements. Diamond (111) and (100) faces in the ?100? and ?110? directions were tested. It was found the synthetic diamond with nitrogen impurity concentration of 0.3ppm exceeds other diamond types with respect to

V. Blank; M. Popov; G. Pivovarov; N. Lvova; S. Terentev

1999-01-01

260

Chemical-Vapor-Deposited Diamond Film  

NASA Technical Reports Server (NTRS)

This chapter describes the nature of clean and contaminated diamond surfaces, Chemical-vapor-deposited (CVD) diamond film deposition technology, analytical techniques and the results of research on CVD diamond films, and the general properties of CVD diamond films. Further, it describes the friction and wear properties of CVD diamond films in the atmosphere, in a controlled nitrogen environment, and in an ultra-high-vacuum environment.

Miyoshi, Kazuhisa

1999-01-01

261

Building Diamond-free Posets Aaron Dutle  

E-print Network

Building Diamond-free Posets Aaron Dutle AMS Southeastern Sectional October 5, 2013 Joint with ´Eva Czabarka, Travis Johnston, and L´aszl´o Sz´ekely Dutle Building Diamond-free Posets #12;The Diamond Johnston, and L´aszl´o Sz´ekely Dutle The Diamond Conjecture is False #12;#12;Building Diamond-free Posets

Biro, Csaba

262

Diamond and Related Materials 6 ( 1997) 1759-I771 Simulation of morphological instabilities during diamond  

E-print Network

Diamond and Related Materials 6 ( 1997) 1759- I771 Simulation of morphological instabilities during diamond chemical vapor deposition P. Mahalingam, D.S. Dandy * Departnlent of Chemical Engineering Abstract The diamond chemical vapor deposition (CVD) process has been investigated theoretically

Dandy, David

263

Carrier transport mechanism of Ohmic contact to p-type diamond  

NASA Astrophysics Data System (ADS)

The carrier transport mechanism through the p-diamond/metal interface was studied by measuring specific contact resistances (?c) using a transmission line method for Ti, Mo, and Cr (carbide forming metals) and Pd and Co (carbon soluble metals) metals contacting to the boron-doped polycrystalline diamond films. Schottky barrier heights (?B) of around 0.5 eV were measured for the annealed contacts. The present result indicates that formation of thermally stable graphite layers at the diamond/metal interfaces upon annealing would pin the Fermi level of the p-diamond. This model led to the preparation of in situ Ohmic contacts by depositing a thin diamondlike carbon on the p-diamond surface prior to metal deposition, and also to excellent Schottky contacts with breakdown voltages higher than 900 V. The present experiment concluded that the existence of a graphite layer at the diamond/metal interface controlled the electrical properties through the p-diamond/metal interface.

Yokoba, M.; Koide, Yasuo; Otsuki, A.; Ako, F.; Oku, T.; Murakami, Masanori

1997-05-01

264

Carbonatitic melts in diamond inclusions  

NASA Astrophysics Data System (ADS)

Fluid inclusions in diamonds are commonly smaller than a micrometer and form clouds or concentric zones carrying many millions of inclusions. Fluid composition varies between four end-members: Hydrous melts rich in silica and alkalis, carbonatitic melts rich in magnesium and calcium, brines rich in chlorine and potassium and sulfide melts rich in iron and nickel. Carbonatitic melts were found together with all the other fluids. No mixing or mutual occurrence was detected between the other three end-members. The carbonatitic melts in most diamonds are rich in magnesium, calcium and iron and carry variable amounts of alkalies and barium. Carbonate and water absorption in the IR spectrum along with EPMA detection of variable amounts of chlorine, silica and phosphorus indicate that the micro-inclusions trapped carbonatitic melts. A clear continuous array extends from the carbonatitic melt composition towards the hydrous, silicic end member. Another array connects the carbonatitic melt with the brines. The occurrence of carbonatitic melts in conjunction with all other fluids indicates their important role in the evolution of all fluids and in diamond growth. This is also supported by experimental diamond growth from carbonate-rich melts at pressures and temperatures recorded by natural diamonds. Carbon for diamond growth may originate from reduction of the carbonate in the melt, dissolved elemental carbon or contemporaneous resorption of other diamonds. Metasomatic interaction with melts or fluids is evident in many diamond-inclusions and xenocrysts. The carbonatitic melts as well as the other melts and brines can account for many such enrichment or resetting events. The entrapment of these fluids in diamond micro-inclusions provides a unique opportunity for a direct study of their composition and evolution.

Izraeli, E. S.; Klein-Bendavid, O.; Navon, O.

2003-04-01

265

Electrochemically grafted polypyrrole changes photoluminescence of electronic states inside nanocrystalline diamond  

NASA Astrophysics Data System (ADS)

Hybrid diamond-organic interfaces are considered attractive for diverse applications ranging from electronics and energy conversion to medicine. Here we use time-resolved and time-integrated photoluminescence spectroscopy in visible spectral range (380-700 nm) to study electronic processes in H-terminated nanocrystalline diamond films (NCD) with 150 nm thin, electrochemically deposited polypyrrole (PPy) layer. We observe changes in dynamics of NCD photoluminescence as well as in its time-integrated spectra after polymer deposition. The effect is reversible. We propose a model where the PPy layer on the NCD surface promotes spatial separation of photo-generated charge carriers both in non-diamond carbon phase and in bulk diamond. By comparing different NCD thicknesses we show that the effect goes as much as 200 nm deep inside the NCD film.

Galá?, P.; ?ermák, J.; Malý, P.; Kromka, A.; Rezek, B.

2014-12-01

266

Synthesis of a diamond and metal mixture by the chemical vapor deposition process  

NASA Astrophysics Data System (ADS)

A mixture of diamond and metal film was synthesized by a hybrid process combining plasma-jet chemical vapor deposition and a plasma-spray process. Sprayed molybdenum and tungsten were changed to Mo2C and tungsten carbide, respectively, and the lattice constants of Ni, Fe, and Co were increased by carbon-plasma spraying. Adhesion of film to the substrate was improved using the hybrid process to form a layer 50 to 150 microns thick of mixed metal and diamond between the substrate and pure diamond film.

Kawarada, M.; Kurihara, K.; Sasaki, K.

1992-02-01

267

Competitive graphitization and diamond growth on hot-dip aluminized carbon steel substrate  

NASA Astrophysics Data System (ADS)

When carbon steel is directly exposed in 99%H2-1%CH4 gas mixture for plasma enhanced CVD deposition of diamond coatings, an intermediate graphite layer is preferentially formed on the substrate surface, and the substrate is subjected to a severe internal carburization attack. The diamond coatings formed easily delaminate from the steel substrate. Hot dip aluminizing treatment of the carbon steel has markedly promoted diamond nucleation, growth and interfacial adhesion. The formation of graphite intermediate phase on the substrate surface is effectively inhibited and the substrate carburization is also suppressed. The possible mechanism of this transition is discussed based on a series of analytical techniques.

Li, Y. S.; Ma, H. T.; Yang, L. Z.; Zhang, C. Z.; Feng, R. F.; Yang, Q.; Hirose, A.

2014-09-01

268

CVD Diamond Dielectric Accelerating Structures  

SciTech Connect

The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerating structures: high RF breakdown field, extremely low dielectric losses and the highest available thermoconductive coefficient. Using chemical vapor deposition (CVD) cylindrical diamond structures have been manufactured with dimensions corresponding to fundamental TM{sub 01} mode frequencies in the GHz to THz range. Surface treatments are being developed to reduce the secondary electron emission (SEE) coefficient below unity to reduce the possibility of multipactor. The diamond CVD cylindrical waveguide technology developed here can be applied to a variety of other high frequency, large-signal applications.

Schoessow, P.; Kanareykin, A. [Euclid Techlabs, 1375 Piccard Dr Rockville MD 20850 (United States); Gat, R. [CTS Inc., Boston MA (United States)

2009-01-22

269

CVD diamond cost analysis update  

NASA Astrophysics Data System (ADS)

Progress for IBIS Associates in the fourth quarter of 1994 includes discussion with 3M and Research Triangle Institute regarding their radio frequency (RF) CVD diamond deposition technology. Although modeling this technology has not been accomplished, the non-disclosure agreements have been taken care of. IBIS awaits feedback on the schedules of 3M and RTI contacts for modeling to proceed. Also accomplished in the fourth quarter of 1994 was initial discussion with Torch Temed (Arava, Israel) concerning the economics of their DC arcjet CVD diamond deposition technology. IBIS intends to follow up with 3M and RF and analyze the economics of their CVD diamond process.

270

Tailoring nanocrystalline diamond film properties  

DOEpatents

A method for controlling the crystallite size and growth rate of plasma-deposited diamond films. A plasma is established at a pressure in excess of about 55 Torr with controlled concentrations of hydrogen up to about 98% by volume, of unsubstituted hydrocarbons up to about 3% by volume and an inert gas of one or more of the noble gases and nitrogen up to about 98% by volume. The volume ratio of inert gas to hydrogen is preferably maintained at greater than about 4, to deposit a diamond film on a suitable substrate. The diamond film is deposited with a predetermined crystallite size and at a predetermined growth rate.

Gruen, Dieter M. (Downers Grove, IL); McCauley, Thomas G. (Somerville, MA); Zhou, Dan (Orlando, FL); Krauss, Alan R. (Naperville, IL)

2003-07-15

271

Diamond and Diamond-Like Materials as Hydrogen Isotope Barriers  

SciTech Connect

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The purpose of this project was to develop diamond and diamond-like thin-films as hydrogen isotope permeation barriers. Hydrogen embrittlement limits the life of boost systems which otherwise might be increased to 25 years with a successful non-reactive barrier. Applications in tritium processing such as bottle filling processes, tritium recovery processes, and target filling processes could benefit from an effective barrier. Diamond-like films used for low permeability shells for ICF and HEDP targets were also investigated. Unacceptable high permeabilities for hydrogen were obtained for plasma-CVD diamond-like-carbon films.

Foreman, L.R.; Barbero, R.S.; Carroll, D.W.; Archuleta, T.; Baker, J.; Devlin, D.; Duke, J.; Loemier, D.; Trukla, M.

1999-07-10

272

Improved performance in synthetic diamond neutron detectors: Application to boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

An improved thermal and fast neutrons detector is obtained, modifying a recently proposed multilayered homoepitaxial Chemical Vapor Deposition (CVD) diamond detector (M. Marinelli, et al., Appl. Phys. Lett. 89 (2006) 143509), where a 6LiF layer deposited on the sensing layer was used to convert thermal neutrons into charged particles. By sandwiching this layer between two CVD diamond detectors connected in parallel, a better signal-to-background separation is achieved. This allows to use 10B as converting element, so to realize a detector suitable for Boron Neutron Capture Therapy dosimetry. Also, the doubled detector volume enhances the sensitivity to fast neutrons.

Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.

2010-01-01

273

Isolated words: Reply to Diamond  

Microsoft Academic Search

Replies to comments by S. Diamond (1980) on S. R. Sabat's (1979) article on Wilhelm Wundt, suggesting that Wundt was aware of, and had outlined, many problems that continue to animate neuropsychology.

Steven R. Sabat

1980-01-01

274

Fabrication of amorphous diamond films  

DOEpatents

Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

Falabella, S.

1995-12-12

275

Facts about Diamond Blackfan Anemia  

MedlinePLUS

... DBA Diamond Blackfan anemia (DBA) is a rare blood disorder that is also associated with birth defects or ... in the United States and Canada. Related Pages Blood Disorders Homepage CDC’s National Center on Birth Defects and ...

276

Surface Design and Engineering Toward Wear-Resistant, Self-Lubricating Diamond Films and Coatings  

NASA Technical Reports Server (NTRS)

The tribological properties of chemical-vapor-deposited (CVD) diamond films vary with the environment, possessing a Jekyll-and-Hyde character. CVD diamond has low coefficient of friction and high wear resistance in air but high coefficient of friction and low wear resistance in vacuum. Improving the tribological functionality of materials (such as achieving low friction and good wear resistance) was an aim of this investigation. Three studies on the surface design, surface engineering, and tribology of CVD diamond have shown that its friction and wear are significantly reduced in ultrahigh vacuum. The main criteria for judging whether diamond films are an effective wear-resistant, self-lubricating material were coefficient of friction and wear rate, which must be less than 0.1 and on the order of 10(exp 6) cu mm/N(dot)m, respectively. In the first study the presence of a thin film (less than 1 micron thick) of amorphous, nondiamond carbon (hydrogenated carbon, also called diamondlike carbon or DLC) on CVD diamond greatly decreased the coefficient of friction and the wear rate. Therefore, a thin DLC film on CVD diamond can be an effective wear-resistant, lubricating coating in ultrahigh vacuum. In the second study the presence of an amorphous, nondiamond carbon surface layer formed on CVD diamond by ion implantation significantly reduced the coefficient of friction and the wear rate in ultrahigh vacuum. Therefore, such surface layers are acceptable for effective self-lubricating, wear-resistant applications of CVD diamond. In the third study CVD diamond in contact with cubic boron nitride exhibited low coefficient of friction in ultra high vacuum. Therefore, this materials combination can provide an effective self-lubricating, wear-resistant couple in ultrahigh vacuum.

Miyoshi, Kazuhisa

1999-01-01

277

3D neutron and X-ray imaging of diamondiferous eclogites, Siberia: Evidence for the secondary origin of diamonds  

NASA Astrophysics Data System (ADS)

Non-destructive, 3D tomography of diamondiferous eclogites (Siberia) has effectively imaged diamonds and their spatial and textural relationships in situ. A rare suite of 17 diamondiferous eclogites have been analyzed, representing the largest collection outside of Siberia. New innovations in X-ray imaging, in combination with the first effective use of neutron imaging techniques, allow for the identification of secondary metasomatic minerals and the delineation of metasomatic pathways through the eclogites. Combining observations from both imaging techniques provides first-order characterizations and textural descriptions critical for understanding diamond genesis that has heretofore been absent in the literature. Eclogitic diamonds are generally octahedral in morphology, but dodecahedral diamonds are also observed, completely enclosed within the eclogites, implying in situ resorption. Diamonds are never observed in contact with primary minerals - i.e., always surrounded by secondary phases. Primary garnet and clinopyroxene show varying degrees of alteration, discerning the delineation of metasomatic pathways. In general, such pathways are observed as interconnected networks of veinlets, commonly cross-cutting the eclogites. Furthermore, clinopyroxene-rich layers observed show higher degrees of alteration, relative to garnet-rich layers within the same sample, highlighting clinopyroxene as more susceptible to metasomatic alteration than garnet. Diamonds are always observed within such metasomatic pathways. For example, eclogite U-112 contains ~22 macro-diamonds, all of which are contained within an altered clinopyroxene-rich layer. In addition, no spatial relationship is observed between diamonds and sulfide phases. The ubiquitous association of diamonds with metasomatic minerals and pathways provides compelling evidence for the secondary origin of diamonds, in agreement with current interpretations on the origin of diamonds [1,2]. However, diamonds are generally believed to be ancient (1-3 Ga) [3], whereas the metasomatic mineral assemblages observed within eclogites are interpreted to have formed much later, perhaps just prior to incorporation into the rising kimberlite magma [4]. This age dichotomy indicates that either the metasomatic pathways have remained open for billions of years or that diamond growth is significantly younger than previously believed. We suggest that diamond growth may be related to metasomatic fluids circulating just prior to kimberlite emplacement and that diamonds may be significantly younger than previously believed. [1] T. Stachel, J.W. Harris, Ore. Geol. Rev. 34, 5 (2008). [2] Y. Liu et al., Lithos 112S, 1014 (2009). [3] S.B. Shirey, S.H. Richardson, Science 333, 434 (2011). [4] K.C. Misra et al., Contrib. Mineral. Petrol. 146, 696 (2004).

Howarth, G. H.; Pernet-Fisher, J. F.; Sobolev, N. V.; Penumadu, D.; Puplampu, S.; Ketcham, R. A.; Maisano, J. A.; Taylor, D.; Taylor, L. A.

2013-12-01

278

33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).  

Code of Federal Regulations, 2012 CFR

...Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation...Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island)....

2012-07-01

279

33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).  

Code of Federal Regulations, 2013 CFR

...Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation...Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island)....

2013-07-01

280

33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).  

Code of Federal Regulations, 2014 CFR

...Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation...Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island)....

2014-07-01

281

DIAMOND CHEMICAL VAPOR DEPOSITION Nucleation and Early Growth Stages  

E-print Network

DIAMOND CHEMICAL VAPOR DEPOSITION Nucleation and Early Growth Stages by Huimin Liu David S. Dandy of high-quality diamond coatings on preshaped parts and synthesis of free-standing shapes of diamond a reality. Epi- taxial diamond has been grown on diamond and cubic-BN. Polycrystalline diamond films have

Dandy, David

282

Diamonds: Exploration, mines and marketing  

NASA Astrophysics Data System (ADS)

The beauty, value and mystique of exceptional quality diamonds such as the 603 carat Lesotho Promise, recovered from the Letseng Mine in 2006, help to drive a multi-billion dollar diamond exploration, mining and marketing industry that operates in some 45 countries across the globe. Five countries, Botswana, Russia, Canada, South Africa and Angola account for 83% by value and 65% by weight of annual diamond production, which is mainly produced by four major companies, De Beers, Alrosa, Rio Tinto and BHP Billiton (BHPB), which together account for 78% by value and 72% by weight of annual diamond production for 2007. During the last twelve years 16 new diamond mines commenced production and 4 re-opened. In addition, 11 projects are in advanced evaluation and may begin operations within the next five years. Exploration for diamondiferous kimberlites was still energetic up to the last quarter of 2008 with most work carried out in Canada, Angola, Democratic Republic of the Congo (DRC) and Botswana. Many kimberlites were discovered but no new economic deposits were outlined as a result of this work, except for the discovery and possible development of the Bunder project by Rio Tinto in India. Exploration methods have benefitted greatly from improved techniques of high resolution geophysical aerial surveying, new research into the geochemistry of indicator minerals and further insights into the formation of diamonds and the relation to tectonic/structural events in the crust and mantle. Recent trends in diamond marketing indicate that prices for rough diamonds and polished goods were still rising up to the last quarter of 2008 and subsequently abruptly sank in line with the worldwide financial crisis. Most analysts predict that prices will rise again in the long term as the gap between supply and demand will widen because no new economic diamond discoveries have been made recently. The disparity between high rough and polished prices and low share prices of publicly traded diamond companies may be due to investors losing patience with the slow pace or absence of new promising discoveries and switching into shares of base metals and fertilizers for agriculture (potash and phosphates).

Read, George H.; Janse, A. J. A. (Bram)

2009-11-01

283

Carbon onions as nanoscopic pressure cells for diamond formation  

Microsoft Academic Search

SPHERICAL particles of carbon consisting of concentric graphite-like shells ('carbon onions') can be formed by electron irradiation of graphitic carbon materials1,2. Here we report that, when such particles are heated to ~700 °C and irradiated with electrons, their cores can be transformed to diamond. Under these conditions the spacing between layers in the carbon onions decreases from 0.31 in the

F. Banhart; P. M. Ajayan

1996-01-01

284

Stiff diamond/buckypaper carbon hybrids.  

PubMed

Given the specific properties of each carbon allotrope such as high electrical/thermal conductivity of multiwall carbon nanotubes (MWCNT) and extreme hardness and high inertness of nanocrystalline diamond (NCD), the integration of both carbon phases is highly desirable. Therefore, in the present work, buckypapers were produced from MWCNT suspensions and were used as free-standing substrates to be coated with NCD by microwave plasma chemical vapor deposition (MPCVD). The integration of both allotropes was successfully achieved, the CNTs being preserved after diamond growth as confirmed by ?-Raman spectroscopy and scanning electron microscopy (SEM). Additionally, a good linkage was observed, the CNTs remaining embedded within the NCD matrix, thus reinforcing the interface of the resulting hybrid structure. This was corroborated by bending tests in a modified nanohardness tester. The increase of the Young's modulus from 0.3 to 300 GPa after NCD growth enables the use of this material in a wide range of applications including microelectromechanical systems (MEMS). Additionally, a highly anisotropic electrical resistivity behavior was confirmed: low in-plane values were found for the CNT layer (1.39 × 10(-2) ?.cm), while high transverse ones were measured for both the NCD coated and uncoated CNT buckypapers (8.13 × 10(5) and 6.18 × 10(2) ?.cm, respectively). PMID:25412196

Holz, T; Mata, D; Santos, N F; Bdikin, I; Fernandes, A J S; Costa, F M

2014-12-24

285

Boron doping of diamond powder by enhanced diffusion and forced diffusion: Diffusion concentrations, mechanical, chemical and optical properties  

NASA Astrophysics Data System (ADS)

Diamond, with its unique mechanical properties, is an excellent material for a wide range of applications. However, there exist some problems. One such problem is integration of diamond of diamond into tool's (usually tungsten-carbide) lattice matrix for the purpose of increasing its performance. The presence of cobalt in the matrix, which acts as a poison for diamond, causes graphitization and degradation of diamond. In addition, diamond graphitizes at sintering temperatures (1770 K). The results of this work suggest that boron has produced a protective layer for diamond, thus reducing the effects of annealing at high temperatures. Boron has been introduced into single crystal high pressure, high temperature diamond powder by enhanced diffusion and forced diffusion techniques. Enhanced diffusion resulted in higher concentrations of boron in diamond powder. Total boron concentrations of 500 to 600 ppm, and 10sp{20} cmsp{-3} at a depth of 0.5 micrometer, have been achieved. Hardness tests performed on doped samples reveal that diamond did not lose its strength due to diffusion at elevated temperatures. Raman spectroscopy and X-ray diffraction analysis did not show any change in the "quality" of diamond due to doping. Oxidation experiments performed on doped and undoped samples revealed that the samples with the highest boron concentrations had superior performance and resistance to oxidation. Final weight loss in these samples was much less than in undoped samples and samples with low boron concentrations. Scanning electron microscopy of these samples showed that degradation due to oxidation of heavily doped diamond samples was significantly less than other samples.

Golshani, Fariborz

286

Diamond magnetometry of superconducting thin films  

NASA Astrophysics Data System (ADS)

In recent years, diamond magnetometers based on the nitrogen-vacancy (NV) center have been of considerable interest for applications at the nanoscale. An interesting application which is well suited for NV centers is the study of nanoscale magnetic phenomena in superconducting materials. We employ NV centers to interrogate magnetic properties of a thin-layer yttrium barium copper oxide (YBCO) superconductor. Using fluorescence-microscopy methods and samples integrated with an NV sensor on a microchip, we measure the temperature of phase transition in the layer to be 70.0(2) K and the penetration field of vortices to be 46(4) G. We observe pinning of the vortices in the layer at 65 K and estimate their density after cooling the sample in a ˜10-G field to be 0.45(1) ?m-2. These measurements are done with a 10-nm-thick NV layer, so that high spatial resolution may be enabled in the future. Based on these results, we anticipate that this magnetometer could be useful for imaging the structure and dynamics of vortices. As an outlook, we present a fabrication method for a superconductor chip designed for this purpose.

Waxman, A.; Schlussel, Y.; Groswasser, D.; Acosta, V. M.; Bouchard, L.-S.; Budker, D.; Folman, R.

2014-02-01

287

Diamond and Related Materials 9 (2000) 12631269 www.elsevier.com/locate/diamond  

E-print Network

for patterning synthetic diamond nano-grit ontopretreatment steps involving at some point the use of a polishedDiamond and Related Materials 9 (2000) 1263­1269 www.elsevier.com/locate/diamond Properties of electron field emitters prepared by selected area deposition of CVD diamond carbon films N.A. Fox a,*, M

Bristol, University of

288

Combined single-crystalline and polycrystalline CVD diamond substrates for diamond electronics  

SciTech Connect

The fabrication of diamond substrates in which single-crystalline and polycrystalline CVD diamond form a single wafer, and the epitaxial growth of diamond films on such combined substrates containing polycrystalline and (100) single-crystalline CVD diamond regions are studied.

Vikharev, A. L., E-mail: val@appl.sci-nnov.ru; Gorbachev, A. M. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Dukhnovsky, M. P. ['Istok' Scientific and Industrial Enterprise (Russian Federation); Muchnikov, A. B., E-mail: mab1@appl.sci-nnov.ru [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Ratnikova, A. K.; Fedorov, Yu. Yu. ['Istok' Scientific and Industrial Enterprise (Russian Federation)

2012-02-15

289

Diamond and Related Materials 8 (1999) 16861696 www.elsevier.com/locate/diamond  

E-print Network

Diamond and Related Materials 8 (1999) 1686­1696 www.elsevier.com/locate/diamond Synthesis of diamond in high power-density microwave methane/hydrogen/oxygen plasmas at elevated substrate temperatures and oxygen additive on the chemical vapor deposition of diamond are presented. High power-density microwave

Tzeng, Yonhua

290

Diamond and Related Materials 8 (1999) 18631874 www.elsevier.com/locate/diamond  

E-print Network

Diamond and Related Materials 8 (1999) 1863­1874 www.elsevier.com/locate/diamond Characterization of diamond J.M. Larson, M.T. Swihart 1, S.L. Girshick * Department of Mechanical Engineering, University atmospheric-pressure radio- frequency (RF) plasma diamond chemical vapor deposition (CVD). Model predictions

Swihart, Mark T.

291

Welcome to Diamond Light Source Parking Visitors can park outside Diamond  

E-print Network

Welcome to Diamond Light Source Parking ­ Visitors can park outside Diamond House, or if that is full, in the Visitor car park. Users should park around the ring. On Arrival ­ Diamond does not have 8500). Then take a seat 2 and wait for your Diamond contact to collect you. Users ­ Fast track users

Crowther, Paul

292

Electron microscopic evidence for a tribologically induced phase transformation as the origin of wear in diamond  

SciTech Connect

Tribological testing of a coarse-grained diamond layer, deposited by plasma-enhanced chemical vapor deposition, was performed on a ring-on-ring tribometer with a diamond counterpart. The origin of the wear of diamond and of the low friction coefficient of 0.15 was studied by analyzing the microstructure of worn and unworn regions by transmission and scanning electron microscopy. In the worn regions, the formation of an amorphous carbon layer with a thickness below 100?nm is observed. Electron energy loss spectroscopy of the C-K ionization edge reveals the transition from sp{sup 3}-hybridized C-atoms in crystalline diamond to a high fraction of sp{sup 2}-hybridized C-atoms in the tribo-induced amorphous C-layer within a transition region of less than 5?nm thickness. The mechanically induced phase transformation from diamond to the amorphous phase is found to be highly anisotropic which is clearly seen at a grain boundary, where the thickness of the amorphous layer above the two differently oriented grains abruptly changes.

Zhang, Xinyi; Schneider, Reinhard; Müller, Erich; Gerthsen, Dagmar [Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), Engesserstr. 7, D-76131 Karlsruhe (Germany); Mee, Manuel; Meier, Sven [Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstr. 11, D-79108 Freiburg (Germany); Gumbsch, Peter [Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstr. 11, D-79108 Freiburg (Germany); Institute for Applied Materials IAM, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, D-76131 Karlsruhe (Germany)

2014-02-14

293

Comparative study of electrical properties of nano to polycrystalline diamond films  

NASA Astrophysics Data System (ADS)

Low-resistance ohmic or Schotky contacts between diamond and metal is primary goal of electronic devices and microsystems based on diamond. The contact resistance depends not only on the choice of metals but also on annealing, layer thickness and other parameters. Combination of titanium, platinum and gold (with co-deposited gold on top to prevent oxidation) is most widely used and yields to good conductivy after being annealed. Diamond films were grown by Microwave Plasma (MP) and Hot Filament Chemical Vapor Deposition (HF CVD) on Si substrates. The dependence of electrical properties on the film morphology was studied. The surface morphology of grown layers was analyzed by scanning electron microscopy (SEM). The different crystallographic character of diamond layers, i.e. either polycrystalline or nanocrystalline, was achieved by using different deposition conditions. Lower-quality diamond films were less sensitive to variation in the operating conditions. The film break-down voltage and other electrical parameters strongly depend on the morphological character, the grain size and defects in layers.

Vojs, M.; Kromka, A.; Ižák, T.; Škriniarová, J.; Novotný, I.; Valent, P.; Michalka, M.; Ková?ik, T.; Veselý, M.

2008-03-01

294

Self-assembled GaN nanowires on diamond.  

PubMed

We demonstrate the nucleation of self-assembled, epitaxial GaN nanowires (NWs) on (111) single-crystalline diamond without using a catalyst or buffer layer. The NWs show an excellent crystalline quality of the wurtzite crystal structure with m-plane faceting, a low defect density, and axial growth along the c-axis with N-face polarity, as shown by aberration corrected annular bright-field scanning transmission electron microscopy. X-ray diffraction confirms single domain growth with an in-plane epitaxial relationship of (10 ?10)(GaN) [parallel] (01 ?1)(Diamond) as well as some biaxial tensile strain induced by thermal expansion mismatch. In photoluminescence, a strong and sharp excitonic emission reveals excellent optical properties superior to state-of-the-art GaN NWs on silicon substrates. In combination with the high-quality diamond/NW interface, confirmed by high-resolution transmission electron microscopy measurements, these results underline the potential of p-type diamond/n-type nitride heterojunctions for efficient UV optoelectronic devices. PMID:22506554

Schuster, Fabian; Furtmayr, Florian; Zamani, Reza; Magén, Cesar; Morante, Joan R; Arbiol, Jordi; Garrido, Jose A; Stutzmann, Martin

2012-05-01

295

Epitaxy of cubic boron nitride on (001)-oriented diamond.  

PubMed

Cubic boron nitride (c-BN), although offering a number of highly attractive properties comparable to diamond, like hardness, chemical inertness and a large electronic bandgap, up to now has not found the attention it deserves. This mostly has to do with preparational problems, with easy chemical routes not available and, instead, the necessity to apply ion-bombardment-assisted methods. Hence, most of the c-BN samples prepared as thin films have been nanocrystalline, making the prospect of using this material for high-temperature electronic applications an illusion. Although heteroepitaxial nucleation of c-BN on diamond substrates has been demonstrated using the high-pressure-high-temperature technique, none of the low-pressure methods ever succeeded in the epitaxial growth of c-BN on any substrate. Here, we demonstrate that heteroepitaxial c-BN films can be prepared at 900 degrees C on highly (001)-oriented diamond films, formed by chemical vapour deposition, using ion-beam-assisted deposition as a low-pressure technique. The orientation relationship was found to be c-BN(001)[100]||diamond(001)[100]. High-resolution transmission electron microscopy additionally proved that epitaxy can be achieved without an intermediate hexagonal BN layer that is commonly observed on various substrates. PMID:12692532

Zhang, X W; Boyen, H-G; Deyneka, N; Ziemann, P; Banhart, F; Schreck, M

2003-05-01

296

Ultimate Atomic Bling: Nanotechnology of Diamonds  

SciTech Connect

Diamonds exist in all sizes, from the Hope Diamond to minuscule crystals only a few atoms across. The smallest of these diamonds are created naturally by the same processes that make petroleum. Recently, researchers discovered that these 'diamondoids' are formed in many different structural shapes, and that these shapes can be used like LEGO blocks for nanotechnology. This talk will discuss the discovery of these nano-size diamonds and highlight current SLAC/Stanford research into their applications in electronics and medicine.

Dahl, Jeremy

2010-05-25

297

Fracture of thin synthetic diamond films  

SciTech Connect

Large residual stresses in diamond coatings may result in film failure through splitting, delamination and substrate failure. In addition, the CVD diamond growth environment may degrade the substrate mechanical properties. These issues are examined for diamond-coating of a tool steel alloy. Diamond growth was achieved on the steel substrate with the use of a titanium interlayer. Embrittlement of the Ti interlayer was not evident, however the substrate hardness was severely degraded.

Drory, M.D. [Crystallume, Santa Clara, CA (United States)

1997-05-01

298

Ohmic contacts to semiconducting diamond  

NASA Astrophysics Data System (ADS)

Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam adjust unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner contacts for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic Contacts to Semiconducting Diamond; Tantalum Ohmic Contacts to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific Contact Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.

Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.

1990-10-01

299

Chlorine-activated diamond CVD  

SciTech Connect

A novel method of producing atomic hydrogen and the active carbon species necessary for diamond CVD has been demonstrated. This method starts with the generation of atomic chlorine from the thermal dissociation of molecular chlorine in a resistively heated graphite furnace at temperature from 1,300--1,500 C. Atomic hydrogen and the carbon precursors are subsequently produced through rapid hydrogen abstraction reactions of atomic chlorine with molecular hydrogen and hydrocarbons at the point where they mix. The quality of the diamond deposits has been found to depend on both substrate temperatures and H{sub 2}/C{sub 2} mole ratios. The effects of process parameters such as substrate and furnace temperatures, methane and chlorine flows, and system pressures on diamond growth rates have also been studied by an in situ Fizeau interferometer. The all carbon nature of the activation device and the low activation and deposition temperatures involved in chlorine-activated diamond CVD likely permit diamond depositions free of metal and nitrogen impurities.

Pan, C.; Margrave, J.L.; Hauge, R.H. [Rice Univ., Houston, TX (United States). Dept. of Chemistry

1995-04-01

300

Diamond Composite Films for Protective Coatings on Metals and Method of Formation  

NASA Technical Reports Server (NTRS)

Composite films consisting of diamond crystallites and hard amorphous films such as diamond-like carbon, titanium nitride, and titanium oxide are provided as protective coatings for metal substrates against extremely harsh environments. A composite layer having diamond crystallites and a hard amorphous film is affixed to a metal substrate via an interlayer including a bottom metal silicide film and a top silicon carbide film. The interlayer is formed either by depositing metal silicide and silicon carbide directly onto the metal substrate, or by first depositing an amorphous silicon film, then allowing top and bottom portions of the amorphous silicon to react during deposition of the diamond crystallites, to yield the desired interlayer structure.

Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

1997-01-01

301

YBa2Cu3O7 thin films on nanocrystalline diamond films for HTSC bolometer  

NASA Technical Reports Server (NTRS)

Superconducting YBa2Cu3O(7-x) films on nanocrystalline diamond thin films have been fabricated. A composite buffer layer system consisting of diamond/Si3N4/YSZ/YBCO was explored for this purpose. The as-deposited YBCO films were superconducting with Tc of about 84 K and a relatively narrow transition width of about 8 K. SEM cross sections of the films showed very sharp interfaces between diamond/Si3N4 and between Si3N4/YSZ. The deposited YBCO film had a surface roughness of about 1000 A, which is suitable for high-temperature superconductive (HTSC) bolometer fabrication. It was also found that preannealing of the nanocrystalline diamond thin films at high temperature was very important for obtaining high-quality YBCO films.

Cui, G.; Beetz, C. P., Jr.; Boerstler, R.; Steinbeck, J.

1993-01-01

302

Diamond Amplified Photocathodes John Smedley1  

E-print Network

acting as a barrier between the primary cathode and the cavity. Synthetic diamond has exhibited secondaryDiamond Amplified Photocathodes John Smedley1 , Ilan Ben-Zvi1 , Jen Bohon2 , Xiangyun Chang1 protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic

303

Pro-Q Diamond Phosphoprotein Gel Stain  

E-print Network

Pro-Q Diamond Phosphoprotein Gel Stain In-gel Detection Technology for Protein Phosphorylation and phosphoproteomics, the Pro-Q Diamond phos- phoprotein gel stain is a breakthrough technology that provides a simple phosphoproteins, the Pro-Q Diamond signal is linear over three orders of magnitude and the strength of the signal

Lebendiker, Mario

304

Traditionally configured prawn trawls contain small diamond-  

E-print Network

434 Traditionally configured prawn trawls contain small diamond- shaped meshes in the codend, and small diamond-mesh sections. A strategically located panel of 85-mm netting was inserted on the bar with a conventional diamond-mesh codend (control) showed that both square-mesh designs significantly re- duced

305

Diamond-free Families Jerrold R. Griggs  

E-print Network

Diamond-free Families Jerrold R. Griggs Wei-Tian Li Linyuan Lu August 28, 2011 Abstract Given. For k 2 let Dk denote the k-diamond poset {A that continues to stymie all interested researchers is the diamond poset on four elements. We present a better

Griggs, Jerrold R.

306

Jared M. Diamond: physiologist, ornithologist, geographer, ecologist  

E-print Network

Jared M. Diamond: physiologist, ornithologist, geographer, ecologist John C. Mittermeier Louisiana State University, BIOL 7083 April 3, 2014 #12;Why Jared Diamond? #12;#12;1937 1961 1966 1964 #12;In Diamond's words, he divides his time between four things 1. Teaching undergraduate geography 2. Field

Harms, Kyle E.

307

Oxidative etching of cleaved synthetic diamond {1 1 1} surfaces  

NASA Astrophysics Data System (ADS)

In this study, three commonly used methods for oxidative etching of diamond {1 1 1} faces are compared: gas phase etching using `dry' oxygen, gas phase etching using an oxygen/water vapour mixture and liquid etching in molten potassium nitrate. The synthetic diamond surfaces are prepared by cleavage. The morphology of the surfaces is studied using atomic force microscopy and the kinetics of the reactions is determined by measuring the decrease in thickness of the diamond. The atomic arrangement of the {1 1 1} surfaces etched in oxygen/water is studied using surface X-ray diffraction. Upon dry oxygen etching, the {1 1 1} faces are roughened and become morphologically unstable. This observation conflicts with standard theory, which predicts {1 1 1} to be a stable F-face that should etch via a layer mechanism. A possible explanation for this is chemical roughening. The addition of water vapour to the oxygen has a dramatic effect on the etching mechanism of the {1 1 1} faces. Now etching proceeds via a layer mechanism involving monoatomic steps. Shallow etch pits are formed, of which the slope increases for increasing etching temperature. Surface X-ray diffraction experiments show that the surface is -OH terminated. For potassium nitrate etching, the {1 1 1} face etches also via a layer mechanism and triangular etch pits with rounded corners are formed, having point or flat bottoms. This etching technique appears to be the best method to reveal different types of defects ending on diamond {1 1 1} surfaces.

de Theije, F. K.; van Veenendaal, E.; van Enckevort, W. J. P.; Vlieg, E.

2001-10-01

308

Development of Designer Diamond Technology for High Pressure High Temperature Experiments in Support of Stockpile Stewardship Program  

SciTech Connect

The role of nitrogen in the fabrication of designer diamond was systematically investigated by adding controlled amount of nitrogen in hydrogen/methane/oxygen plasma. This has led to a successful recipe for reproducible fabrication of designer diamond anvils for high-pressure high-temperature research in support of stockpile stewardship program. In the three-year support period, several designer diamonds fabricated with this new growth chemistry were utilized in high-pressure experiments at UAB and Lawrence Livermore National Laboratory. The designer diamond anvils were utilized in high-pressure studies on heavy rare earth metals, high pressure melting studies on metals, and electrical resistance measurements on iron-based layered superconductors under high pressures. The growth chemistry developed under NNSA support can be adapted for commercial production of designer diamonds.

Vohra, Yogesh, K.

2009-10-28

309

Boron doped nanostructured diamond films  

NASA Astrophysics Data System (ADS)

A chemical vapor deposition hydrogen/methane/nitrogen feed-gas mixture with unconventionally high methane (15% CH4 by volume) normally used to grow ultra-hard and smooth nanostructured diamond films on Ti-6Al-4V alloy substrates was modified to include diborane B2H6 for boron-doping of diamond films. The flow rates for B2H 6 and N2 were varied to investigate their effect on plasma chemistry, film structure, boron incorporation, and mechanical properties. It was found that boron atoms can easily be incorporated into diamond films and change the lattice constant and film structure. Nitrogen, on the other hand, competes with boron in the plasma and acts to prevent boron incorporation into the diamond structure. In addition, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well faceted diamond to nanocrystalline diamond. Glancing angle X-ray diffraction and Micro-Raman were used as the main tools to investigate the relation between processing and structure. An optimal N2/CH4 ratio of 0.4 was found to result in a film with a minimum in grain size and surface roughness, along with high boron incorporation (˜4 x 1020 cm-3). Mechanical properties and thermal stability of boron doped nanostructured diamond films were examined by means of nanoindentation, open air thermal annealing, and nanotribometry. It was found that the films have high hardness close to that of undoped nanostructured diamond films. Thermal stability of these films was evaluated by heating in an oxygen environment above 700°C. Improved thermal stability of boron doped nanostructured diamond films was observed. Tribological tests show that although both undoped and boron doped nanostructured diamond films show extremely low coefficient of friction and wear rate as compared with uncoated titanium alloys (Ti-6Al-4V) and cobalt chrome alloy (Co-Cr-Mo), a critical failure max stress of 2.2 GPa was observed for boron doped nanostructured diamond films. A FORTRAN Chemical Kinetics Package for the Analysis of Gas Phase Chemical Kinetics, gas-phase thermodynamic equilibrium calculations involving H 2/CH4/N2/B2H6 mixtures was employed to investigate the chemical interactions leading to boron incorporation and crystalline structure variations. The strong influence of the BH 3 in causing the boron incorporation and the role of CN radical in causing the nanocrystallinity are confirmed by the correlation of their modeled compositions in the gas phase with boron content and degree of nanocrystallinity as determined experimentally. A good degree of agreement was obtained between the theoretically predicted gas phase concentration of species and the experimental concentration trends as measured by the optical emission spectroscopy of the microwave plasma. Overall, high film hardness and toughness, combined with good thermal stability and low surface roughness, indicate that nanostructured boron doped diamond films can be used as wear resistant coatings that are able to withstand high temperature oxidizing environments.

Liang, Qi

310

Properties of hybridized DNA arrays on single-crystalline undoped and boron-doped (100) diamonds studied by atomic force microscopy in electrolytes.  

PubMed

Properties of hybridized deoxyribonucleic acid (DNA) arrays on single-crystalline undoped and boron-doped diamonds are studied at the microscopic level by atomic force microscopy (AFM) in buffered electrolytic solutions. DNA is linked to diamond via aminodecene molecules (TFAAD) that are attached to undoped diamonds by a photochemical reaction and via nitrophenyl-diazonium molecules attached electrochemically to boron-doped diamonds. Both H-terminated and oxidized diamond surfaces are used in this process. On H-terminated surfaces, AFM measurements detect compact DNA layers. By analyzing phase and height contrast in AFM, a DNA layer height of 76 A is determined on the photochemically functionalized diamonds and a DNA layer height of up to 92 A is determined on the electrochemically functionalized diamonds. Based on the layer thickness, the DNA chains are tilted under the angle of 31 degrees . The morphology of the DNA layers exhibits long-range (30-50 nm) undulations of 20 A in height and a nanoroughness of 8 A. Using Hertz's model for calculating the contact area of the AFM tip on a DNA layer and a geometrical model of DNA arrangement on diamond yields the DNA density on diamonds of 6 x 10(12) cm(-2) on both photochemically and electrochemically functionalized diamonds. The structure of these dense DNA layers is not significantly influenced by variations in buffer salinity of 1-300 mM NaCl. DNA molecules can be removed from the diamond surface by contact-mode AFM with forces >or= 45 nN and >or= 76 nN on photochemically and electrochemically functionalized diamonds, respectively, indicating that DNA is bonded covalently and stronger on diamond than on gold substrates. The DNA arrangement and bonding strength are similar on oxidized diamond surfaces when using an electrochemical process. On oxidized surfaces after photochemical processing, DNA is bonded noncovalently as deduced from the removal force < 6 nN. The presence of hybridized DNA as well as the selective removal of DNA by AFM scanning are corroborated by fluorescence microscopy. PMID:17547423

Rezek, Bohuslav; Shin, Dongchan; Nebel, Christoph E

2007-07-01

311

Spectroscopic ellipsometry of homoepitaxial diamond multilayers and delta-doped structures  

SciTech Connect

The optimization of diamond-based unipolar electronic devices such as pseudo-vertical Schottky diodes or delta-doped field effect transistors relies in part on the sequential growth of nominally undoped (p{sup –}) and heavily boron doped (p{sup ++}) layers with well-controlled thicknesses and steep interfaces. Optical ellipsometry offers a swift and contactless method to characterize the thickness, roughness, and electronic properties of semiconducting and metallic diamond layers. We report ellipsometric studies carried out on delta-doped structures and other epitaxial multilayers with various boron concentrations and thicknesses (down to the nanometer range). The results are compared with Secondary Ion Mass Spectroscopy and transport measurements.

Bousquet, J.; Chicot, G.; Eon, D.; Bustarret, E. [Univ. Grenoble Alpes, Inst. NEEL, F-38042 Grenoble (France); CNRS, Inst. NEEL, F-38042 Grenoble (France)

2014-01-13

312

Diamond metallization for device applications  

NASA Astrophysics Data System (ADS)

Nearly any diamond electronic or sensor device needs at least one ohmic contact. These contacts play a key role in the overall device performance. This paper reviews the dependence of the Schottky barrier height on the surface termination and the impact of annealing of carbide-forming metals on the specific contact resistivity to diamond. It is concluded that carbide patches dominate the specific contact resistivity after annealing. Furthermore, the doping dependence of the specific contact resistivity and suitable diffusion barriers, which avoid interdiffusion of the contact scheme, are briefly discussed.

Werner, Matthias

2003-03-01

313

Method for machining steel with diamond tools  

DOEpatents

The present invention is directed to a method for machining optical quality inishes and contour accuracies of workpieces of carbon-containing metals such as steel with diamond tooling. The wear rate of the diamond tooling is significantly reduced by saturating the atmosphere at the interface of the workpiece and the diamond tool with a gaseous hydrocarbon during the machining operation. The presence of the gaseous hydrocarbon effectively eliminates the deterioration of the diamond tool by inhibiting or preventing the conversion of the diamond carbon to graphite carbon at the point of contact between the cutting tool and the workpiece.

Casstevens, John M. (Greenville, TX)

1986-01-01

314

Method for machining steel with diamond tools  

DOEpatents

The present invention is directed to a method for machine optical quality finishes and contour accuracies of workpieces of carbon-containing metals such as steel with diamond tooling. The wear rate of the diamond tooling is significantly reduced by saturating the atmosphere at the interface of the workpiece and the diamond tool with a gaseous hydrocarbon during the machining operation. The presence of the gaseous hydrocarbon effectively eliminates the deterioration of the diamond tool by inhibiting or preventing the conversion of the diamond carbon to graphite carbon at the point of contact between the cutting tool and the workpiece.

Casstevens, J.M.

1984-01-01

315

Diamond Wars? Conflict Diamonds and Geographies of Resource Wars  

Microsoft Academic Search

In the late 1990s, natural resources such as oil, diamonds, and timber came under increased scrutiny by conflict analysts and media outlets for their purported role in many contemporary wars. This article discusses some of the limitations of conventional arguments linking wars and resources. Dominated by econometric approaches and rational choice theory interpretations, arguments pertaining to “resource wars” often oversimplify

Philippe Le Billon

2008-01-01

316

Charge Collection and Propagation in Diamond X-ray Detectors  

SciTech Connect

Diamond is a unique material for x-ray energy conversion. Its high thermal conductivity and low coefficient of thermal expansion make it ideal for high heat load environments. High material strength and x-ray transmission also are potentially useful features for certain applications in x-ray science. However, its large bandgap, while offering insensitivity to visible light, makes charge trapping more likely (thermal detrapping less likely) than in silicon; energy conversion efficiency is also 3-4 times less even under the best conditions. Limitations to charge collection efficiency such as recombination and charge trapping have been investigated quantitatively using quasi-continuous tunable synchrotron radiation under flexible biasing schemes as well using detailed Monte Carlo simulations. In the case of charge collection efficiency, the magnitude of the applied field, initial particle energy, and probe depth are adjusted. The diffusion and drift of photo-generated charge clouds are explicitly considered for the specific scattering behavior of diamond. While recombination loss at the entrance window of diamond diodes is qualitatively similar to a treatment for an additional 'dead' carbon window layer, the observed field and photon energy dependence implies that the more sophisticated model is more correct quantitatively. In addition, charge propagation in diamond is unique in that photoconductive gain is possible. Effectively, charge trapping of one carrier leads to screening of the applied field. In order to avoid photoconductive gain, either blocking contacts or explicit detrapping is required. Initial investigations of photoconductive gain as a function of applied field, waveform and photon energy have provided insight into the performance of state of the art single crystal diamond. Simple models are proposed to assist in extrapolating the observed behavior towards useful detector devices.

Keister, J.; Smedley, J; Dimitrov, D; Busby, R

2010-01-01

317

Charge Collection and Propagation in Diamond X-Ray Detectors  

SciTech Connect

Diamond is a unique material for x-ray energy conversion. Its high thermal conductivity and low coefficient of thermal expansion make it ideal for high heat load environments. However, its large bandgap, while offering insensitivity to visible light, makes charge trapping more likely (thermal detrapping less likely) than in silicon; energy conversion efficiency is also 3-4 times less even under the best conditions. High material strength and x-ray transmission also are potentially useful features for certain applications in x-ray science. Limitations to charge collection efficiency such as recombination and charge trapping have been investigated quantitatively using quasi-continuous tunable synchrotron radiation under flexible biasing schemes as well using detailed Monte Carlo Simulations. In the case of charge collection efficiency, the magnitude of the applied field, initial particle energy, and probe depth are adjusted. The diffusion and drift of photo-generated charge clouds are explicitly considered for the specific energy loss behavior of diamond. While recombination loss at the entrance window of diamond diodes is qualitatively similar to a treatment for an additional 'dead' carbon window layer, the observed field and photon energy dependence implies that the more sophisticated model is more correct quantitatively. In addition, charge propagation in diamond is unique in that photoconductive gain is possible. Effectively, charge trapping of one carrier leads to screening of the applied field. In order to avoid photoconductive gain, either blocking contacts or explicit detrapping is required. Quantitative analysis of photoconductive gain as a function of applied field, x-ray power, waveform and photon energy offers insight into the fundamental limitations of state of the art single crystal diamond. Simple models are proposed to assist in extrapolating the observed behavior towards useful detector devices.

Keister, J.W.; Smedley, J.; Dimitrov, D.; Busby, R.

2009-11-13

318

Improved luminescence properties of pulsed laser deposited Eu:Y{sub 2}O{sub 3}thin films on diamond coated silicon substrates  

SciTech Connect

Europium activated yttrium oxide (Eu:Y{sub 2}O{sub 3}) phosphor films have been grown {ital in situ} on (100) bare and diamond-coated silicon substrates using a pulsed laser deposition technique. Diamond-coated silicon substrates were prepared using hot filament chemical vapor deposition of diamond onto silicon. Photoluminescence brightness from Eu:Y{sub 2}O{sub 3} films grown at 700{degree}C on diamond-coated silicon substrates was about twice that of films on bare silicon, and reached 80{percent} of the brightness of powders. The higher brightness from Eu:Y{sub 2}O{sub 3} film on diamond-coated silicon substrates is attributed to reduced internal reflections from the Eu:Y{sub 2}O{sub 3} film surface, which results from the roughness of the diamond layer. {copyright} {ital 1997 American Institute of Physics.}

Cho, K.G.; Kumar, D.; Lee, D.G.; Jones, S.L.; Holloway, P.H.; Singh, R.K. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400 (United States)] [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400 (United States)

1997-12-01

319

OH and H2O of garnets in diamond-bearing and diamond-free garnet-clinopyroxene rocks from the Kumdy-kol area, Kokchetav Massif  

NASA Astrophysics Data System (ADS)

Garnet-clinopyroxene (Grt-Cpx) rocks consisting mainly of Grt + Na-poor Cpx + calcite with various proportions, occur in the Kumdy-kol area. Diamond-bearing Grt-Cpx rock was first reported by Sobolev and Shatsky (1990) and has been well-known as one of the Kokchetav diamond-bearing rocks. UHP evidence, e.g., coesite exsolution from supersilicic titanite, was discovered also in the diamond-free Grt-Cpx rock (Inoue and Ogasawara, 2003). Presence/lack of diamond in Grt-Cpx rocks is one of important features to understand the stability of diamond in the Kokchetav UHP calcsilicate and carbonate rocks. We focused on OH and H2O in garnets in two types of Grt-Cpx rock to clarify fluid conditions during UHP metamorphism. One of the samples, the diamond-bearing Grt-Cpx rock (sample no. 25018; provided by Prof. H.-P. Schertl) is composed of two monomineralic layers, Grt-layer and Cpx-layer, with minor amounts of rutile and calcite. Coarse-grained diamond (up to 0.15 mm across) is included in garnet. Another Grt-Cpx rock, diamond-free one (sample no. XX16) shows a glanoblastic texture, and consists of Grt (30 %) + Cpx (30 %) + calcite (30 %) × titanite (5 %) with exsolved coesite-needles and plates. The precursor supersilicic compositions of titanite indicate six-coordinated Si at UHP conditions (Ogasawara et al, 2002; Sakamaki and Ogasawara, IGR in press). To understand the fluid environments during the formation of these two calcsilicate rocks, we chose garnets and conducted micro FT-IR spectroscopy. IR spectra of garnets in the diamond-bearing Grt-Cpx rock showed OH bands at 3430 and 3570 cm-1, sometimes with a week band at 3675 cm-1. The absorption band at 3570 cm-1 is the strongest and is sharp, whereas the band at 3430 cm-1 is broad. IR spectra of garnets in diamond-free one show strong OH bands at 3400 and 3555 cm-1, sometimes with week bands at 3590 and 3640 cm-1. The OH band at 3555 cm-1 is the strongest and is sharp, whereas the band at 3400 cm-1 is broad. IR analyses of garnets in the Grt-Cpx rocks show bimodal spectra; the relatively sharp band at ~3550 cm-1 and the broad band at ~3400 cm-1. The former band is attributed to OH in garnet structure and the latter one molecular H2O. The similar bimodal spectra were obtained from garnet in diamond-bearing dolomite marble. When we regard the total absorption at the range of 3100-3750 cm-1 as structural OH, the garnets in diamond-bearing Grt-Cpx rock contain 797 to 2506 ppm wt. H2O, and those in the diamond-free Grt-Cpx rock contain 679 to 2169 ppm wt. H2O. To evaluate the absorption spectra of the garnets in the Grt-Cpx rocks, we analyzed the garnet of different origin, Cr- and pyrope-rich garnet in mantle peridotite from the Garnet Ridge, northern Arizona. This peridotitic garnet shows a single-modal absorption band of OH at 3575 cm-1. No molecular H2O band was detected. Such results suggest that the environment during Kokchetav UHP metamorphism of calcsilicate may be saturated in H2O in contrast with the peridotitic garnet from the Garnet Ridge. The molecular H2O in the garnets of the Kokchetav Grt-Cpx rocks probably is submicron fluid inclusions trapped during UHP metamorphism. We thank Prof. H.-P. Schertl for providing us a very precious sample, diamond-bearing garnet-clinopyroxene rock.

Sakamaki, K.; Ogasawara, Y.

2013-12-01

320

CVD diamond film oxidation resistance research  

NASA Astrophysics Data System (ADS)

Diamond films were deposited on a silicon substrate by microwave plasma chemical vapor deposition system, and its oxidation experiments were carried out in atmospheric environmental condition by using a muffle furnace. Inatmospheric environment (the temperature is from 400°C to 900°C) the oxidation resistance of diamond thin films was investigated. The results indicate that under the atmospheric environment diamond thin film surface morphology did not change after 6 hours at 400°C. Diamond thin film surface morphology began to change after 2 hours at 600°C, and when time was extended to 4 hours, the diamond thin film surface morphology changed significantly. The surface morphology of diamond films began to change after 15 minutes at a 700°C condition and when time was extended to 6 hours diamond films were all destroyed. All the diamond films on the silicon substrate disappeared completely in 20 minutes at 900°C. The intact crystal face is the reason that natural diamond has stable chemical property. The crystal face of synthetic diamond film has a lot of defects, especially on the side. Oxidation of the diamond films begin with the grain boundary and defects.

Jing, Longwei; Wang, Xiaoping; Wang, Lijun; Pan, Xiufang; Sun, Yiqing; Wang, Jinye; Sun, Hongtao

2013-12-01

321

Friction and wear performance of boron doped, undoped microcrystalline and fine grained composite diamond films  

NASA Astrophysics Data System (ADS)

Chemical vapor deposition (CVD) diamond films have attracted more attentions due to their excellent mechanical properties. Whereas as-fabricated traditional diamond films in the previous studies don't have enough adhesion or surface smoothness, which seriously impact their friction and wear performance, and thus limit their applications under extremely harsh conditions. A boron doped, undoped microcrystalline and fine grained composite diamond (BD-UM-FGCD) film is fabricated by a three-step method adopting hot filament CVD (HFCVD) method in the present study, presenting outstanding comprehensive performance, including the good adhesion between the substrate and the underlying boron doped diamond (BDD) layer, the extremely high hardness of the middle undoped microcrystalline diamond (UMCD) layer, as well as the low surface roughness and favorable polished convenience of the surface fine grained diamond (FGD) layer. The friction and wear behavior of this composite film sliding against low-carbon steel and silicon nitride balls are studied on a ball-on-plate rotational friction tester. Besides, its wear rate is further evaluated under a severer condition using an inner-hole polishing apparatus, with low-carbon steel wire as the counterpart. The test results show that the BD-UM-FGCD film performs very small friction coefficient and great friction behavior owing to its high surface smoothness, and meanwhile it also has excellent wear resistance because of the relatively high hardness of the surface FGD film and the extremely high hardness of the middle UMCD film. Moreover, under the industrial conditions for producing low-carbon steel wires, this composite film can sufficiently prolong the working lifetime of the drawing dies and improve their application effects. This research develops a novel composite diamond films owning great comprehensive properties, which have great potentials as protecting coatings on working surfaces of the wear-resistant and anti-frictional components.

Wang, Xinchang; Wang, Liang; Shen, Bin; Sun, Fanghong

2014-12-01

322

Catalytic activity of platinum nanoparticles on highly boron-doped and 100-oriented epitaxial diamond towards HER and HOR.  

PubMed

Platinum nanoparticles supported on boron-doped single-crystalline diamond surfaces were used as a model system to investigate the catalytic activity with respect to the influence of particle morphology, particle density and surface preparation of the diamond substrates. We report on the preparation, characterization and activity regarding hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) of these Pt/diamond electrodes. Two kinds of diamond layers with boron doping above 10(20) cm(-3) were grown epitaxially on (100)-oriented diamond substrates; post-treatments of wet chemical oxidation and radio frequency (rf) oxygen plasma treatments were applied. Electrochemical deposition of Pt was performed using a potentiostatic double-pulse technique, which allowed variation of the particle size in the range between 1 nm and 15 nm in height and 5 nm and 50 nm in apparent radius, while keeping the particle density constant. Higher nucleation densities on the plasma processed surface at equal deposition parameters could be related to the plasma-induced surface defects. Electrochemical characterization shows that the platinum particles act as nanoelectrodes and form an ohmic contact with the diamond substrate. The catalytic activity regarding HER and HOR of the platinum nanoparticles exhibits no dependence on the particle size down to particle heights of ?1 nm. The prepared Pt on diamond(100) samples show a similar platinum-specific activity as bulk platinum. Therefore, while keeping the activity constant, the well-dispersed particles on diamond offer an optimized surface-to-material ratio. PMID:21687867

Brülle, Tine; Denisenko, Andrej; Sternschulte, Hadwig; Stimming, Ulrich

2011-07-28

323

Zr/oxidized diamond interface for high power Schottky diodes  

SciTech Connect

High forward current density of 10{sup 3} A/cm{sup 2} (at 6 V) and a breakdown field larger than 7.7 MV/cm for diamond diodes with a pseudo-vertical architecture, are demonstrated. The power figure of merit is above 244 MW/cm{sup 2} and the relative standard deviation of the reverse current density over 83 diodes is 10% with a mean value of 10{sup ?9} A/cm{sup 2}. These results are obtained with zirconium as Schottky contacts on the oxygenated (100) oriented surface of a stack comprising an optimized lightly boron doped diamond layer on a heavily boron doped one, epitaxially grown on a Ib substrate. The origin of such performances are discussed.

Traoré, A., E-mail: aboulaye.traore@neel.cnrs.fr; Muret, P.; Fiori, A.; Eon, D.; Gheeraert, E. [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Pernot, J., E-mail: julien.pernot@neel.cnrs.fr [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Institut Universitaire de France, 103 Boulevard Saint-Michel, F-75005 Paris (France)

2014-02-03

324

Heteroepitaxial growth of highly oriented diamond on cubic silicon carbide  

SciTech Connect

We have deposited epitaxial diamond films with very low angular spread on epitaxial {beta}-phase silicon carbide layers on silicon (001) substrates. From x-ray rocking curve measurements, half-widths of the angular spread of the crystal orientation as low as 0.6{degree} have been determined, which is the smallest value ever reported in heteroepitaxial diamond films and appears to be smaller than those of the {beta}-phase silicon carbide underlayers. The film surface exhibits a roughness of about 100 nm with very few discernible boundaries due to misorientation. The optimization of the bias-enhanced nucleation process and the control of selective growth are the main factors for the improvement of the crystallinity. {copyright} {ital 1997 American Institute of Physics.}

Kawarada, H.; Wild, C.; Herres, N.; Locher, R.; Koidl, P. [Fraunhofer-Institut fuer Angewandte Festkoerperphysik, Tullastrasse 72, D-79108 Freiburg (Germany)] [Fraunhofer-Institut fuer Angewandte Festkoerperphysik, Tullastrasse 72, D-79108 Freiburg (Germany); Nagasawa, H. [R D Center, Hoya Corporation, 3-3-1, Musashino, Akishima-shi, Tokyo 196 (Japan)] [R D Center, Hoya Corporation, 3-3-1, Musashino, Akishima-shi, Tokyo 196 (Japan)

1997-04-01

325

Diamond-like amorphous carbon  

Microsoft Academic Search

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications

J. Robertson

2002-01-01

326

High thermal conductivity of diamond  

NASA Technical Reports Server (NTRS)

The objectives of this educational exercise were to demonstrate the high rate of heat flow from a synthetic diamond coupon and to compare it to a commonly used thermal conductor, such as copper. The principles of heat transfer by conduction and convection may also be demonstrated. A list of equipment and supplies and the procedure for the experiment are presented.

Stephan, Patrick M.

1993-01-01

327

Natural and synthetic polycrystalline diamond, with emphasis on ballas  

Microsoft Academic Search

The successful synthesis of diamond by chemical vapor deposition (CVD) at low pressures has generated renewed interest in polycrystalline diamond. It is now possible to deposit on relatively large surfaces a metal-free ‘polycrystalline diamond ceramic’, which is nearly equivalent in optical, thermal and mechanical properties to single crystal diamond. Some microstructures found in CVD diamond are clearly related to those

B. Lux; R. Haubner; H. Holzer; R. C. DeVries

1997-01-01

328

High temperature diffusion chromizing as a successful method for CVD-diamond coating of steel—Part II  

Microsoft Academic Search

Well adherent CVD-diamond coatings were deposited onto 41Cr4 steel substrates using chromium carbide diffusion interlayers. The influence of coating parameters on microstructure and composition of chromium carbide layer and substrate was investigated. In situ heat treatment allows for a variation of physical and mechanical properties of the substrate. We assume that the adhesion of CVD-diamond coatings depends inter alia on

S. Schwarz; S. M. Rosiwal; Y. Musayev; R. F. Singer

2003-01-01

329

Diamond-coated ATR prism for infrared absorption spectroscopy of surface-modified diamond nanoparticles  

NASA Astrophysics Data System (ADS)

Linear antenna microwave chemical vapor deposition process was used to homogeneously coat a 7 cm long silicon prism by 85 nm thin nanocrystalline diamond (NCD) layer. To show the advantages of the NCD-coated prism for attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) of nanoparticles, we apply diamond nanoparticles (DNPs) of 5 nm nominal size with various surface modifications by a drop-casting of their methanol dispersions. ATR-FTIR spectra of as-received, air-annealed, plasma-oxidized, and plasma-hydrogenated DNPs were measured in the 4000-1500 cm-1 spectral range. The spectra show high spectral resolution, high sensitivity to specific DNP surface moieties, and repeatability. The NCD coating provides mechanical protection against scratching and chemical stability of the surface. Moreover, unlike on bare Si surface, NCD hydrophilic properties enable optically homogeneous coverage by DNPs with some aggregation on submicron scale as evidenced by scanning electron microscopy and atomic force microscopy. Compared to transmission FTIR regime with KBr pellets, direct and uniform deposition of DNPs on NCD-ATR prism significantly simplifies and speeds up the analysis (from days to minutes). We discuss prospects for in situ monitoring of surface modifications and molecular grafting.

Remes, Z.; Kozak, H.; Rezek, B.; Ukraintsev, E.; Babchenko, O.; Kromka, A.; Girard, H. A.; Arnault, J.-C.; Bergonzo, P.

2013-04-01

330

Multiple Diamond Anvil (MDA) apparatus using nano-polycrystalline diamond  

NASA Astrophysics Data System (ADS)

Thanks to the great efforts by Dave Mao, Bill Bassett, Taro Takahashi, and their colleagues at the University of Rochester through 1960s-70s, diamond anvil cell (DAC) became a major tool to investigate the deep Earth after its invention by scientists at NBS in 1958. DAC can now cover almost the entire pressure and temperature regimes of the Earth's interior, which seems to have solved the longstanding debate on the crystal structure of iron under the P-T conditions of the Earth's inner core. In contrast, various types of static large-volume presses (LVP) have been invented, where tungsten carbide has conventionally been used as anvils. Kawai-type multianvil apparatus (MA), which utilize 6 first-stage harden steel and 8 tungsten carbide anvils, is the most successful LVP, and has been used for accurate measurements of phase transitions, physical properties, element partitioning, etc. at high pressure and temperature. However, pressures using tungsten carbide as the second-stage anvils have been limited to about 30 GPa due to significant plastic deformation of the anvils. Efforts have been made to expand this pressure limit by replacing tungsten carbide anvils with harder sintered diamond (SD) anvils over the last two decades, but the pressures available in KMA with SD anvils have still been limited to below 100 GPa. We succeeded to produce nano-polycrystalline diamond (NPD or HIME-Diamond) in 2003, which is known to have ultrahigh hardness, very high toughness and elastic stiffness, high transmittance of light, relatively low thermal conductivity. These properties are feasible for its use as anvils, and some preliminary experiments of application of NPD anvils to laser heated DAC have successfully made in the last few years. We are now able to synthesize NPD rods with about 1cm in both diameter and length using a newly constructed 6000-ton KMA at Geodynamics Research Center, Ehime University, and have just started to apply this new polycrystalline diamond as anvils for multianvil apparatus. Various versions of the Multiple Diamond Anvil (MDA) apparatus with NPD anvils (Fig.1), amalgamated forms of MA and DAC, are currently being tested for experiments under Mbar regimes without sacrificing the advantages of MA over DAC.

Irifune, T.; Kunimoto, T.; Tange, Y.; Shinmei, T.; Isobe, F.; Kurio, A.; Funakoshi, K.

2011-12-01

331

Medical applications of diamond particles and surfaces.  

SciTech Connect

Diamond has been considered for use in several medical applications due to its unique mechanical, chemical, optical, and biological properties. In this paper, methods for preparing synthetic diamond surfaces and particles are described. In addition, recent developments involving the use of diamond in prostheses, sensing, imaging, and drug delivery applications are reviewed. These developments suggest that diamond-containing structures will provide significant improvements in the diagnosis and treatment of medical conditions over the coming years. Diamond is an allotrope of carbon that is being considered for use in several medical applications. Ramachandran determined that the crystal structure of diamond consists of two close packed interpenetrating face centered cubic lattices; one lattice is shifted with respect to the other along the elemental cube space diagonal by one-quarter of its length. If one approximates carbon atoms as equal diameter rigid spheres, the filling of this construction is 34%. Due to the carbon-carbon distance (1.54 {angstrom}), diamond crystal exhibits the highest atomic density (1.76 x 10{sup 23} cm{sup -3}) of any solid. The very high bond energy between two carbon atoms (83 kcal/mol) and the directionality of tetrahedral bonds are the main reasons for the high strength of diamond. Diamond demonstrates the highest Vickers hardness value of any material (10,000 kg/mm{sup 2}). The tribological properties of diamond are also impressive; the coefficient of friction of polished diamond is 0.07 in argon and 0.05 in humid air. Diamond is resistant to corrosion except in an oxygen atmosphere at temperatures over 800 C. In addition, type IIa diamond exhibits the highest thermal conductivity of all materials (20 W cm{sup -1} K{sup -1} at room temperature).

Narayan, R. J.; Boehm, R. D.; Sumant, A. V. (Center for Nanoscale Materials); (Univ. of California)

2011-04-01

332

Friction and wear of synthetic diamond with and without N + implantation and CVD diamond coating in air, water and methanol  

Microsoft Academic Search

The friction and wear of synthetic diamond with and without N+ implantation and CVD diamond coatings were studied in air, water and methanol. It was shown that water effectively reduced the friction of the synthetic diamond and CVD diamond at lighter loads, but methanol did not. Wear of the diamond was minimal in methanol. N+ ion implantation was less effective

Y. Enomoto; S. Miyake; S. Yazu

1996-01-01

333

Measurements and Studies of Secondary Electron Emission of Diamond Amplified Photocathode  

SciTech Connect

The Diamond Amplified Photocathode (DAP) is a novel approach to generating electrons. By following the primary electron beam, which is generated by traditional electron sources, with an amplifier, the electron beam available to the eventual application is increased by 1 to 2 orders of magnitude in current. Diamond has a very wide band gap of 5.47eV which allows for a good negative electron affinity with simple hydrogenation, diamond can hold more than 2000MV/m field before breakdown. Diamond also provides the best rigidity among all materials. These two characters offer the capability of applying high voltage across very thin diamond film to achieve high SEY and desired emission phase. The diamond amplifier also is capable of handling a large heat load by conduction and sub-nanosecond pulse input. The preparation of the diamond amplifier includes thinning and polishing, cleaning with acid etching, metallization, and hydrogenation. The best mechanical polishing available can provide high purity single crystal diamond films with no less than 100 {micro}m thickness and <15 nm Ra surface roughness. The ideal thickness for 700MHz beam is {approx}30 {micro}m, which requires further thinning with RIE or laser ablation. RIE can achieve atomic layer removal precision and roughness eventually, but the time consumption for this procedure is very significant. Laser ablation proved that with <266nm ps laser beam, the ablation process on the diamond can easily achieve removing a few microns per hour from the surface and <100nm roughness. For amplifier application, laser ablation is an adequate and efficient process to make ultra thin diamond wafers following mechanical polishing. Hydrogenation will terminate the diamond surface with monolayer of hydrogen, and form NEA so that secondary electrons in the conduction band can escape into the vacuum. The method is using hydrogen cracker to strike hydrogen atoms onto the bare diamond surface to form H-C bonds. Two independent experiments were carried out to determine the transport of the electrons within the diamond and their emission at the surface. In transmission mode measurements, the diamond amplifier was coated with metal on both sides, so results simply depend only on the electron transport within the diamond. The SEY for this mode provides one secondary electron per 20eV energy, which gives the gain of more than 200 for 4.7keV (effective energy) primary electrons under 2MV/m. Laser detrapping can help the signal maintain the gain with lops pulse and duty cycle of 1.67 x 10{sup -7}. In emission mode measurements, in which the diamond is prepared as in the actual application, the SEY is {approx}20 for 700eV (effective energy) primary electrons under 1.21MV/m. The electric field applied and the primary electron energy is limited by the experiment setup, but the results show good trend toward large gain under high field. Thermal emittance of the diamond secondary emission is critical for the beam application. A careful design is setup to measure with very fine precision and accuracy of 0.01eV.

Wu,Q.

2008-10-01

334

Photo- and electrochemical bonding of DNA to single crystalline CVD diamond  

NASA Astrophysics Data System (ADS)

Alkene and nitrophenyl molecules have been covalently bonded to single crystal diamond using photochemical and electrochemical techniques. The surface density of electrochemically grafted nitrophenyl groups is about 5% of a monolayer (8 × 1013 molecules/cm2) on initially H-terminated diamond. Covalently-bonded nitrophenyl groups on single-crystalline diamond are characterized to have two successive reversible one-electron transfer reactions due to a regularly-oriented arrangement. On oxidized surface of boron doped electrodes, a slightly (10%) smaller density is detected. Photochemical attachment of alkene molecules results also in a well arranged films as detected by angle resolved X-ray photoelectron spectroscopy (XPS). The density of 10-amino-dec-1-ene molecules protected with trifluoroacetic acid (TFAAD) is calculated to be in the range 2 × 1014 molecules/cm2. The bonding mechanism of Alkene molecules to high quality hydrogen terminated single crystalline CVD diamond has been characterized using a variety of experiments which show that photo-excited electrons of 5 eV energy trigger the photochemical attachment. The minimum time required to achieve a monolayer attachment of TFAAD molecules on (100)(2 × 1):H diamond is discussed and compared with experimental data from XPS. The benzene and alkene linker molecules are then reacted with the heterobifunctional cross linker sulphosuccinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate and finally with thiol-modified ss-DNA to produce a DNA-modified diamond surface. The interaction with complementary and partially mismatched DNA is characterized by fluorescence microscopy. Microscopic properties of DNA layers on diamond have been characterized by contact- and oscillatory-mode atomic force microscopy (AFM). A comparison of bonding forces, detected by contact mode AFM, reveals significant bonding strength differences. For both, electro- and photochemically bonded DNA, tilted molecule arrangements are detected, with angles in the range 30 ° to 46° with respect to the diamond surface. The DNA films are dense with a surface roughness of about 5 Å.

Shin, D.; Rezek, B.; Tokuda, N.; Takeuchi, D.; Watanabe, H.; Nakamura, T.; Yamamoto, T.; Nebel, C. E.

2006-10-01

335

21 CFR 872.4535 - Dental diamond instrument.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Dental diamond instrument. 872.4535 Section 872...Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device...

2013-04-01

336

21 CFR 872.4535 - Dental diamond instrument.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Dental diamond instrument. 872.4535 Section 872...Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device...

2014-04-01

337

21 CFR 872.4535 - Dental diamond instrument.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Dental diamond instrument. 872.4535 Section 872...Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device...

2012-04-01

338

Network-Aware Partitioning of Computation in Diamond  

E-print Network

Network-Aware Partitioning of Computation in Diamond Alex Nizhner1 Larry Huston2 Peter Steenkiste Pittsburgh, PA 15213 Abstract The Diamond storage architecture enables efficient interactive search efficient use of resources under dynamic conditions, Diamond adaptively partitions computation among

339

Chemical vapor deposited diamond-on-diamond powder composites (LDRD final report)  

SciTech Connect

Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. The authors developed techniques for forming diamond powder precursors and densified these precursors in a hot filament-assisted reactor and a microwave plasma-assisted reactor. Densification conditions were varied following a fractional factorial statistical design. A number of conclusions can be drawn as a result of this study. High density diamond powder green bodies that contain a mixture of particle sizes solidify more readily than more porous diamond powder green bodies with narrow distributions of particle sizes. No composite was completely densified although all of the deposits were densified to some degree. The hot filament-assisted reactor deposited more material below the exterior surface, in the interior of the powder deposits; in contrast, the microwave-assisted reactor tended to deposit a CVD diamond skin over the top of the powder precursors which inhibited vapor phase diamond growth in the interior of the powder deposits. There were subtle variations in diamond quality as a function of the CVI process parameters. Diamond and glassy carbon tended to form at the exterior surface of the composites directly exposed to either the hot filament or the microwave plasma. However, in the interior, e.g. the powder/substrate interface, diamond plus diamond-like-carbon formed. All of the diamond composites produced were grey and relatively opaque because they contained flawed diamond, diamond-like-carbon and glassy carbon. A large amount of flawed and non-diamond material could be removed by post-CVI oxygen heat treatments. Heat treatments in oxygen changed the color of the composites to white.

Panitz, J.K.; Hsu, W.L.; Tallant, D.R.; McMaster, M.; Fox, C.; Staley, D.

1995-12-01

340

Laser damage threshold of diamond films  

NASA Astrophysics Data System (ADS)

The possibility that diamond films may inhibit laser-induced damage to optical components in laser systems films was investigated by measuring laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced CVD process. It was found that free-standing diamond films had the highest laser damage threshold at 1064 nm. For a diamond film of 630 nm, the damage threshold was found to be 7 J/sq cm, as compared to a damage threshold of 4.5 J/sq cm for bare silicon, and a low value of 1.5 J/sq cm for the film/substrate combination. The damage mechanism is considered to involve melting or dielectric breakdown induced by laser radiation. The low value of the film/substrate combination is attributed to film stress and conditions of film deposition.

Albin, Sacharia; Cropper, Andre D.; Watkins, Linwood C.; Byvik, Charles E.; Buoncristiani, A. Martin

1989-03-01

341

Laser damage threshold of diamond films  

NASA Technical Reports Server (NTRS)

The possibility that diamond films may inhibit laser-induced damage to optical components in laser systems films was investigated by measuring laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced CVD process. It was found that free-standing diamond films had the highest laser damage threshold at 1064 nm. For a diamond film of 630 nm, the damage threshold was found to be 7 J/sq cm, as compared to a damage threshold of 4.5 J/sq cm for bare silicon, and a low value of 1.5 J/sq cm for the film/substrate combination. The damage mechanism is considered to involve melting or dielectric breakdown induced by laser radiation. The low value of the film/substrate combination is attributed to film stress and conditions of film deposition.

Albin, Sacharia; Cropper, Andre D.; Watkins, Linwood C.; Byvik, Charles E.; Buoncristiani, A. Martin

1989-01-01

342

Diamond nanowires: fabrication, structure, properties, and applications.  

PubMed

C(sp(3) )?C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Young's modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications. PMID:25376154

Yu, Yuan; Wu, Liangzhuan; Zhi, Jinfang

2014-12-22

343

Understanding diamond pricing using unconditional quantile regressions  

E-print Network

Abstract: This paper investigates the relationship between the selling price of diamonds and their weight in carats. For this purpose, we use a unique sample of 112,080 certified diamonds collected from www.info-diamond.com during the first week of July 2011. We find substantial differences in pricing depending on cut shape. The price of diamonds increases markedly with the carat weight, with a price elasticity equal to 1.94. However, estimates from unconditional quantile regressions show that the price-weight elasticity is not constant since it rises along the price distribution of diamonds. Finally, we observe the existence of significant increases in prices for diamonds featured with round weights compared to gems just below these threshold weights.

Nicolas Vaillant; François-charles Wolff

2013-01-01

344

Two-step process for improved diamond deposition on titanium alloys at moderate temperature  

Microsoft Academic Search

A simple two-step process is reported here to deposit diamond coatings on titanium alloys at temperatures equal to or lower than 600 °C. The first step allows us to increase the carbon nucleation rate and to deposit a sacrificial layer which contains more than about 25% sp2 carbon. Its thickness is selected both to limit the interaction of titanium element

L. Vandenbulcke; D. Rats; M. I. De Barros; R. Erre; P. Andreazza

1998-01-01

345

Hot-iron-metal polishing machine for CVD diamond films and characteristics of the polished surfaces  

Microsoft Academic Search

We developed a technique to examine the presence of a damaged layer on a CVD diamond surface, caused by polishing, using etching in hydrogen plasma. Based on the results we developed an apparatus for polishing the flank face of a cutting insert edge using a hot-iron-metal method. Further, we carried out experiments to examine the cutting performance of cutting inserts

Masanori Yoshikawa; Fuminori Okuzumi

1997-01-01

346

ZNO-ON-NANOCRYSTALLINE DIAMOND LATERAL BULK ACOUSTIC RESONATORS Reza Abdolvand, Gavin K. Ho, James Butler*  

E-print Network

-crystalline diamond (NCD) is an emerging material with growing applications in MEMS driven by its superior mechanical-level applications as they are required to interface with low impedance radio frequency (RF) electronics. A resonator layer of oxide with a large positive TCF (~85ppm/ºC) [5] can be used as a passive temperature

Ayazi, Farrokh

347

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear  

DOEpatents

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

Westerfield, Curtis L. (Espanola, NM); Morris, John S. (Los Alamos, NM); Agnew, Stephen F. (Los Alamos, NM)

1997-01-01

348

Infrared optical properties of diamond films and electrical properties of CVD diamond detectors  

NASA Astrophysics Data System (ADS)

In this paper, the infrared optical properties of diamond films grown on silicon substrates by means of the microwave plasma chemical vapour deposition (MPCVD) method were first studied by infrared spectroscopic ellipsometry in the photo energy range of 0.1-0.4 eV. Using the effects of annealing treatment on the extinction coefficient k and refractive index n of diamond films, the infrared optical quality of the diamond film can be significantly improved by thermal annealing treatment in N2 atmosphere. After annealing the value of k was about 10-12-10-15. However, for the non-annealed diamond film, the value of k varied in a large range, about 10-3-10-14. After annealing the refractive index n of the diamond film increased and was close to that of a single crystal, Type IIa natural diamond. The graphite on the diamond surface can be removed to some extent after surface oxidizing treatment of the diamond film in a solution of H2O2 and H2SO4, which causes the obvious decrease of the leakage current of the CVD diamond detector. Based on these diamond films, diamond x-ray detectors with a response time of about 3 ns were fabricated. From the temperature behaviour and the time response of the CVD diamond detector to x-ray irradiation, we find that the various defects or impurities that exist in the film may be responsible for the long fall time.

Wang, Linjun; Xia, Yiben; Shen, Hujiang; Zhang, Minglong; Yang, Ying; Wang, Lin

2003-10-01

349

Diamond Detector Prototyping Outline: Recipe "how to make a diamond detector"  

E-print Network

Diamond Detector Prototyping Outline: Recipe "how to make a diamond detector" 1. Buy 2. Clean Vapour Deposition (CVD) method of diamond synthesis that can be compared to frost forming on a window in various acids/bases (cleaning) Main purpose: to remove all organic and inorganic impurities from

Martin, Jeff

350

Nanotwinned diamond with unprecedented hardness and stability  

NASA Astrophysics Data System (ADS)

Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ~3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of ~5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ~200 GPa and an in-air oxidization temperature more than 200 °C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties.

Huang, Quan; Yu, Dongli; Xu, Bo; Hu, Wentao; Ma, Yanming; Wang, Yanbin; Zhao, Zhisheng; Wen, Bin; He, Julong; Liu, Zhongyuan; Tian, Yongjun

2014-06-01

351

Diamond-silicon carbide composite and method  

DOEpatents

Uniformly dense, diamond-silicon carbide composites having high hardness, high fracture toughness, and high thermal stability are prepared by consolidating a powder mixture of diamond and amorphous silicon. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPam.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness.

Zhao, Yusheng (Los Alamos, NM)

2011-06-14

352

Nanotwinned diamond with unprecedented hardness and stability.  

PubMed

Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30?nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ?3.8?nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of ?5?nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ?200?GPa and an in-air oxidization temperature more than 200?°C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties. PMID:24919919

Huang, Quan; Yu, Dongli; Xu, Bo; Hu, Wentao; Ma, Yanming; Wang, Yanbin; Zhao, Zhisheng; Wen, Bin; He, Julong; Liu, Zhongyuan; Tian, Yongjun

2014-06-12

353

The equilibrium boundary between grahite and diamond  

Microsoft Academic Search

The equilibrium boundary between diamond and graphite has been determined over the temperature interval 1100°C-1625°C. A piston-cylinder apparatus and a ''zero-friction'' cell were used. Pressures were computed by force\\/area measurements and are independent of any calibration points. Visual observations of diamond dissolution or diamond growth were used in fixing the position of the boundary. Our newly determined boundary has the

C. Scott Kennedy; George C. Kennedy

1976-01-01

354

Mineral resource of the month: diamond  

USGS Publications Warehouse

The article presents information on diamond, which is regarded as the world's most popular gemstone. It states that there is strength in the covalent bonding between its carbon atoms, resulting to the strength of its physical properties. The presence of colors in diamonds may be attributed to the impurities that settle in the crystal lattice. Diamonds have been used as decorative items since the ancient era.

Olson, Donald W.

2009-01-01

355

Diamond turning machine controller implementation  

SciTech Connect

The standard controller for a Pnuemo ASG 2500 Diamond Turning Machine, an Allen Bradley 8200, has been replaced with a custom high-performance design. This controller consists of four major components. Axis position feedback information is provided by a Zygo Axiom 2/20 laser interferometer with 0.1 micro-inch resolution. Hardware interface logic couples the computers digital and analog I/O channels to the diamond turning machine`s analog motor controllers, the laser interferometer, and other machine status and control information. It also provides front panel switches for operator override of the computer controller and implement the emergency stop sequence. The remaining two components, the control computer hardware and software, are discussed in detail below.

Garrard, K.P.; Taylor, L.W.; Knight, B.F.; Fornaro, R.J.

1988-12-01

356

Diamond turning of thermoplastic polymers  

SciTech Connect

Single point diamond turning studies were made using a series of thermoplastic polymers with different glass transition temperatures. Variations in surface morphology and surface roughness were observed as a function of cutting speed. Lower glass transition temperatures facilitate smoother surface cuts and better surface finish. This can be attributed to the frictional heating that occurs during machining. Because of the very low glass transition temperatures in polymeric compared to inorganic glasses, the precision machining response can be very speed sensitive.

Smith, E.; Scattergood, R.O.

1988-12-01

357

Microwave Resonators Containing Diamond Disks  

NASA Technical Reports Server (NTRS)

Synthetic diamond dielectric bodies proposed for use in cylindrical resonators helping to stabilize frequencies of some microwave oscillators. Acting in conjunction with metal resonator cavities in which mounted, such dielectric bodies support "whispering-gallery" waveguide modes characterized by desired frequencies of resonance and by electro-magnetic-field configurations limiting dissipation of power on metal surfaces outside dielectric bodies. Performances at room temperature might exceed those of liquid-nitrogen-cooled sapphire-based resonators.

Dick, G. John; Maleki, Lutfollah; Wang, Rabi T.

1996-01-01

358

Cobalt impurities in synthetic diamond  

Microsoft Academic Search

High-quality single crystals of diamond were grown by the temperature-gradient method using cobalt-containing metals as the solvent-catalyst. Cobalt and nickel impurities in the crystals were measured by X-ray fluorescence using synchrotron radiation. Their distributions were imaged by a mapping technique. Their concentrations were also measured at a number of points of the crystals. X-ray absorption near edge structure (XANES) spectroscopic

X. Jia; S. Hayakawa; W. Li; Y. Gohshi; M. Wakatsuki

1999-01-01

359

Electromagnetic Radiation Hardness of Diamond Detectors  

E-print Network

The behavior of artificially grown CVD diamond films under intense electromagnetic radiation has been studied. The properties of irradiated diamond samples have been investigated using the method of thermally stimulated current and by studying their charge collection properties. Diamonds have been found to remain unaffected after doses of 6.8 MGy of 10 keV photons and 10 MGy of MeV-range photons. This observation makes diamond an attractive detector material for a calorimeter in the very forward region of the proposed TESLA detector.

T. Behnke; M. Doucet; N. Ghodbane; A. Imhof; C. Martinez; W. Zeuner

2001-08-22

360

Processing of diamond by laser beam irradiation  

NASA Astrophysics Data System (ADS)

YAG and ArF excimer laser beams, of which wavelengths are 1.06 micrometers and 193 nm respectively, have been applied to processing of a variety of diamonds. Cutting and smoothing of natural, CVD and sintered diamonds have been performed. CVD diamond films were prepared by arc discharge plasma jet CVD and microwave plasma CVD, and sintered diamonds contain metallic or ceramic binder have been used. Fundamental removal processes of diamond with YAG and ArF excimer laser have been investigated using natural single crystal and CVD diamonds in various atmospheres changing laser irradiation conditions such as average power, energy density and pulse repetition rates. Cutting of natural and CVD diamonds with YAG laser proceeds at higher peal power that occurs at lower pulse repetition rates. Smooth surfaces are obtained by excimer laser irradiation at the incident angle of 80 percent. In the cases of the processing with YAG laser, the effect of local heating by laser beam irradiation mainly assists the diamond processing, and diamond appears to be removed after graphitization and oxidization following vaporization in the atmosphere contains oxygen. The temperature measurement was carried out at backside of irradiation surface, and increase of temperature when YAG laser beam was irradiated was larger than that when excimer laser was irradiated. On the contrary, the detection of C, C2, C+, O2 and CO from the emission at the irradiation area with ArF excimer laser beam suggest that processing partly proceeds by the separation of carbon atoms from the surface of diamond after braking bonds between carbon atoms caused by laser beam. Cutting of sintered diamond with metallic binder was difficult because metallic binder remains in the groove while ceramic binder was easily removed. Processing technique using laser beams has been applied to surface planing, chip preparation and edge formation of CVD diamond and curved surface formation on sintered diamond. Surface planing was carried out by directing the YAG laser beam parallel to the surface of diamond films and diamond chips were prepared by the combination of cutting and surface planing techniques. A sharp edge was formed between the surfaces which cut by laser beam and mechanically polished. Round nose was formed by gradually rotating the sintered diamond following YAG laser beam irradiation.

Yoshikawa, Masanori; Hirata, Atsushi

1998-10-01

361

Electrochemical patterning of amorphous carbon on diamond  

NASA Technical Reports Server (NTRS)

The ability to pattern ion-implantation damaged or other nondiamond carbon on a diamond substrate is useful for fabricating a variety of devices. We accomplished such patterning by an unmasked implantation into a diamond substrate followed by photolithography and a selective electrochemical etch. The use of a high resistivity medium coupled with applied biases over 50 V permitted etching without requiring contact between the substrate and an electrode. Many electrolytes gave etches that exhibit high selectivity for nondiamond carbon over both diamond and dielectrics such as photoresist. Optical, electrical, and Raman spectroscopic measurements elucidate the effects of the etch on the implanted diamond surface.

Marchywka, Mike; Pehrsson, Pehr E.; Binari, Steven C.; Moses, Daniel

1993-01-01

362

Negative Electron Affinity Mechanism for Diamond Surfaces  

NASA Technical Reports Server (NTRS)

The energy distribution of the secondary electrons for chemical vacuum deposited diamond films with Negative Electron Affinity (NEA) was investigated. It was found that while for completely hydrogenated diamond surfaces the negative electron affinity peak in the energy spectrum of the secondary electrons is present for any energy of the primary electrons, for partially hydrogenated diamond surfaces there is a critical energy above which the peak is present in the spectrum. This critical energy increases sharply when hydrogen coverage of the diamond surface diminishes. This effect was explained by the change of the NEA from the true type for the completely hydrogenated surface to the effective type for the partially hydrogenated surfaces.

Krainsky, I. L.; Asnin, V. M.

1998-01-01

363

Very High Efficiency, Miniaturized, Long-Lived Alpha Particle Power Source Using Diamond Devices for Extreme Space Environments  

NASA Technical Reports Server (NTRS)

A power source that converts a-particle energy into electricity by coulomb collision in doped diamond films is described. Alpha particle decay from curium-244 creates electron-hole pairs by free- ing electrons and holes inside the crystal lattice in N- and P-doped diamond films. Ohmic contacts provide electrical connection to an electronic device. Due to the built-in electric field at the rectifying junction across the hT- and P-doped diamond films, the free electrons are constrained to traveling in generally one direction. This one direction then supplies electrons in a manner similar to that of a battery. The radioactive curium layer may be disposed on diamond films for even distribution of a-particle radiation. The resulting power source may be mounted on a diamond substrate that serves to insulate structures below the diamond substrate from a-particle emission. Additional insulation or isolation may be provided in order to prevent damage from a-particle collision. N-doped silicon may be used instead of N-doped diamond.

Kolawa, Elizabeth A. (Inventor); Patel, Jagdishbhai U. (Inventor); Fleurial, Jean-Pierre (Inventor)

2004-01-01

364

PREFACE: Science's gem: diamond science 2009 Science's gem: diamond science 2009  

NASA Astrophysics Data System (ADS)

Natural diamond has been valued for its appearance and mechanical properties for at least two thousand years. As a gem stone diamond is unsurpassed. However, scientific work, especially in the last 20 years, has demonstrated that diamond has numerous surprising properties and many unique ones. Some of the extreme properties have been known for many years, but the true scale of diamond's other highly desirable features is still only coming to light as control in the synthesis of diamond, and hence material perfection, improves. The ultimate prize for man-made diamond is surely not in the synthesis of gem stones, but in delivering technological solutions enabled by diamond to the challenges facing our society today. If the special properties are to be exploited to their full potential, at least four crucial factors must be considered. First, there must be sufficient scientific understanding of diamond to make applications effective, efficient and economical. Secondly, the means of fabrication and control of properties have to be achieved so that diamond's role can be optimised. Thirdly, it is not enough that its properties are superior to existing materials: they must be so much better that it is worth initiating new technologies to exploit them. Finally, any substantial applications will have to address the society's major needs worldwide. The clear technology drivers for the 21st century come from the biomedical technologies, the demand for energy subject to global constraints, and the information technologies, where perhaps diamond will provide the major enabling technology [1]. The papers in this volume concern the solid state physics of diamond, and primarily concern the first two factors: understanding, and control of properties. They address many of the outstanding basic problems, such as the identification of existing defects, which affect the material's properties, both desirable and less so. Regarding future substantial applications, one paper discusses diamond's exceptional properties for quantum information processing [2], a topic on which there have been many recent papers, and where a diamond colour centre single photon source is already commercially available. Biomedical applications of diamond are recognised, partly tribological and partly electrochemical, but lie outside the present group of papers. Processing and controlling diamond surfaces and interfaces with other materials in their environment are critical steps en route to exploitation. Boron-doped diamond has already found application in electro-analysis and in the bulk oxidation of dissolved species in solution [3]. Energy-related applications—ranging from high-power electronics [3] to a potential first wall of fusion reactors [4]—are further exciting potential applications. Even small and ugly diamonds have value. Their mechanical properties [5] dominate, with significant niche applications such as thermal sinks. The major applications for diamond to date exploit only a fraction of diamond's special properties: visual for status diamonds, and mechanical for working diamonds. Diamond physics reaches well beyond the usual laboratory, to the geological diamond formation processes in the Earth's mantle. Characterization of natural gem diamonds [6, 7] is one part of the detective story that allows us to understand the conditions under which they formed. It was only half a century ago that the scientific and technological challenges of diamond synthesis were met systematically. Today, most of the recent research on diamond has concentrated on synthetics, whether created using high pressure, high temperature (HPHT) techniques or chemical vapour deposition (CVD). The HPHT synthesis of diamond has advanced dramatically [8, 9] to the extent that dislocation birefringence [10] can be largely eliminated. In silicon technology, the elimination of dislocations was a major step in microelectronics. Now, even diamond can be synthesised containing virtually no dislocations. The understanding of the critical processes that are involved in CVD diamond growth are

Mainwood, Alison; Newton, Mark E.; Stoneham, Marshall

2009-09-01

365

Nano-crystalline tungsten carbide: As incompressible as diamond  

SciTech Connect

We investigate the compressibility of nanocrystalline tungsten carbide (nano-WC) using synchrotron x-ray diffraction. Nano-WC displays a bulk modulus (452 GPa) comparable to that of diamond; it is 10%–15% larger than previously reported values for bulk WC. This finding is consistent with a generalized model of nanocrystal with a compressed surface layer. The linear bulk moduli of nano-WC along a- and c-axes were determined to be 407 and 546 GPa, respectively. First-principles density functional theory (DFT) calculations confirm the experimental observations of an anisotropic linear compressibility and a lower bulk modulus for microsized WC.

Lin, Zhijun; Wang, Lin; Zhang, Jianzhong; Mao, Ho-kwang; Zhao, Yusheng

2009-01-01

366

Method and apparatus for making diamond-like carbon films  

DOEpatents

Ion-assisted plasma enhanced deposition of diamond-like carbon (DLC) films on the surface of photovoltaic solar cells is accomplished with a method and apparatus for controlling ion energy. The quality of DLC layers is fine-tuned by a properly biased system of special electrodes and by exact control of the feed gas mixture compositions. Uniform (with degree of non-uniformity of optical parameters less than 5%) large area (more than 110 cm.sup.2) DLC films with optical parameters varied within the given range and with stability against harmful effects of the environment are achieved.

Pern, Fu-Jann (Golden, CO); Touryan, Kenell J. (Indian Hills, CO); Panosyan, Zhozef Retevos (Yerevan, AM); Gippius, Aleksey Alekseyevich (Moscow, RU)

2008-12-02

367

Bolometric detector embedded in a polycrystalline diamond grown by chemical vapor deposition  

NASA Astrophysics Data System (ADS)

A fast bolometric detector embedded in a plate of chemical-vapor-deposited polycrystalline diamond was developed and fabricated. The working element of the bolometer is a buried graphitized layer (with temperature-sensitive resistance) fabricated in the bulk of a diamond by C+ ion implantation followed by annealing. The kinetics of the response of the structure to irradiation with light from an LGI-21 pulsed nitrogen laser (? = 337 nm, ?P ˜ 8 ns) were studied. The room-temperature response width at half-maximum is ˜ 20 ns. Using the space-time distribution of responses of the structure, thermal (bolometric) signals were resolved from signals of different nature (photoconductivity or photovoltage).

Galkina, T. I.; Klokov, A. Yu.; Sharkov, A. I.; Khmelnitski?, R. A.; Gippius, A. A.; Dravin, V. A.; Ral'Chenko, V. G.; Savel'Ev, A. V.

2007-04-01

368

Diamond photonic crystal slab: Leaky modes and modified photoluminescence emission of surface-deposited quantum dots  

PubMed Central

Detailed analysis of a band diagram of a photonic crystal (PhC) slab prepared on a nano-diamond layer is presented. Even though the PhC is structurally imperfect, the existence of leaky modes, determined both theoretically and experimentally in the broad spectral region, implies that an efficient light interaction with a material periodicity occurs in the sample. It is shown that the luminescence emission spectrum of a light source placed directly on the PhC surface can be modified by employing the optical modes of the studied structure. We stress also the impact of intrinsic optical losses of the nano-diamond on this modification. PMID:23209874

Ondi?, Lukáš; Babchenko, Oleg; Varga, Marián; Kromka, Alexander; ?tyroký, Ji?í; Pelant, Ivan

2012-01-01

369

RAPID COMMUNICATION: Nanostructured diamond film deposition on curved surfaces of metallic temporomandibular joint implant  

NASA Astrophysics Data System (ADS)

Microwave plasma chemical vapour deposition of nanostructured diamond films was carried out on curved surfaces of Ti-6Al-4V alloy machined to simulate the shape of a temporomandibular joint (TMJ) dental implant. Raman spectroscopy shows that the deposited films are uniform in chemical composition along the radius of curvature of the TMJ condyle. Thin film x-ray diffraction reveals an interfacial carbide layer and nanocrystalline diamond grains in this coating. Nanoindentation hardness measurements show an ultra-hard coating with a hardness value of 60+/-5 GPa averaged over three samples.

Fries, Marc D.; Vohra, Yogesh K.

2002-10-01

370

The mechanical and strength properties of diamond  

NASA Astrophysics Data System (ADS)

Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials based on carbon, namely the fullerenes and graphines have been identified in recent years and are now the subject of intense research.

Field, J. E.

2012-12-01

371

The mechanical and strength properties of diamond.  

PubMed

Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials based on carbon, namely the fullerenes and graphines have been identified in recent years and are now the subject of intense research. PMID:23168381

Field, J E

2012-12-01

372

Raman Scattering in Natural Diamond Crystals Implanted with High-Energy Ions and Irradiated with Fast Neutrons  

NASA Astrophysics Data System (ADS)

Raman scattering is studied in natural diamond crystals with radiation-induced defects produced by implantation of high energy Xe and Kr ions (ion kinetic energy >1 MeV/amu) and by irradiation with fast reactor neutrons (kinetic energy >100 keV). Confocal measurements of the Raman spectra along the surface of an oblique section of the ionimplanted diamonds are used to study the radiation damage profile. The evolution of the Raman scattering spectra with depth of the damaged layer in the ion-implanted diamonds, and as a function of annealing temperature of the neutron-irradiated diamond, is determined by spatial localization of phonons in the radiation disordered crystal lattice and by the formation of associations of intrinsic defects in the lattice.

Poklonskaya, O. N.; Vyrko, S. A.; Khomich, A. A.; Averin, A. A.; Khomich, A. V.; Khmelnitsky, R. A.; Poklonskia, N. A.

2015-01-01

373

Single Color Centers Implanted in Diamond Nanostructures  

E-print Network

The development of materials processing techniques for optical diamond nanostructures containing a single color center is an important problem in quantum science and technology. In this work, we present the combination of ion implantation and top-down diamond nanofabrication in two scenarios: diamond nanopillars and diamond nanowires. The first device consists of a 'shallow' implant (~20nm) to generate Nitrogen-vacancy (NV) color centers near the top surface of the diamond crystal. Individual NV centers are then isolated mechanically by dry etching a regular array of nanopillars in the diamond surface. Photon anti-bunching measurements indicate that a high yield (>10%) of the devices contain a single NV center. The second device demonstrates 'deep' (~1\\mu m) implantation of individual NV centers into pre-fabricated diamond nanowire. The high single photon flux of the nanowire geometry, combined with the low background fluorescence of the ultrapure diamond, allows us to sustain strong photon anti-bunching even at high pump powers.

Birgit J. M. Hausmann; Thomas M. Babinec; Jennifer T. Choy; Jonathan S. Hodges; Sungkun Hong; Irfan Bulu; A. Yacoby; M. D. Lukin; Marko Lon?ar

2010-09-21

374

Double bevel construction of a diamond anvil  

DOEpatents

A double or multiple bevel culet geometry is used on a diamond anvil in a high pressure cell apparatus to provide increased sample pressure and stability for a given force applied to the diamond tables. Double or multiple bevel culet geometries can also be used for sapphire or other hard crystal anvils. Pressures up to and above 5 Megabars can be reached. 8 figs.

Moss, W.C.

1988-10-11

375

Energy Harvesting Diamond Channel with Energy Cooperation  

E-print Network

Energy Harvesting Diamond Channel with Energy Cooperation Berk Gurakan Sennur Ulukus Department@umd.edu Abstract--We consider the energy harvesting diamond channel, where the source and two relays harvest energy the option of wirelessly transferring some of its energy to the relays via energy cooperation. We find

Ulukus, Sennur

376

The World According to Jared Diamond.  

ERIC Educational Resources Information Center

Reviews the book, "Guns, Germs, and Steel: The Fates of Human Societies" (Jared Diamond). Examines the strengths of the book, focusing on its distinctive aspects, while also offering criticism. States that the final chapter is the most problematic part of Diamond's work. (CMK)

McNeil, J. R.

2001-01-01

377

Double bevel construction of a diamond anvil  

DOEpatents

A double or multiple bevel culet geometry is used on a diamond anvil in a high pressure cell apparatus to provide increased sample pressure and stability for a given force applied to the diamond tables. Double or multiple bevel culet geometries can also be used for sapphire or other hard crystal anvils. Pressures up to and above 5 Megabars can be reached.

Moss, William C. (San Mateo, CA)

1988-01-01

378

Fluorinated diamond bonded in fluorocarbon resin  

DOEpatents

By fluorinating diamond grit, the grit may be readily bonded into a fluorocarbon resin matrix. The matrix is formed by simple hot pressing techniques. Diamond grinding wheels may advantageously be manufactured using such a matrix. Teflon fluorocarbon resins are particularly well suited for using in forming the matrix.

Taylor, Gene W. (Los Alamos, NM)

1982-01-01

379

Diamond film growth argon-carbon plasmas  

DOEpatents

A method and system for manufacturing diamond film. The method involves forming a carbonaceous vapor, providing a gas stream of argon, hydrogen and hydrocarbon and combining the gas with the carbonaceous vapor, passing the combined carbonaceous vapor and gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the carbonaceous and deposition of a diamond film on a substrate.

Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (Naperville, IL); Liu, Shengzhong (Canton, MI); Pan, Xianzheng (Wuhan Hubei, CN); Zuiker, Christopher D. (LaGrange, IL)

1998-01-01

380

Microstructure and mechanical properties of diamond films on titanium-aluminum-vanadium alloy  

NASA Astrophysics Data System (ADS)

The primary focus of this dissertation is the investigation of the processing-structure-property relationships of diamond films deposited on Ti-6Al-4V alloy by microwave plasma chemical vapor deposition (MPCVD). By depositing a well-adhered protective layer of diamond on an alloy component, its hardness, wear-resistance, performance, and overall lifetime could be significantly increased. However, due to the large thermal expansion mismatch between the diamond film and metal (and the corresponding residual stress induced in the film), film adhesion is typically unsatisfactory and often results in immediate delamination after processing. Therefore, it is a major goal of this research to improve adhesion of the diamond film to the alloy substrate. Through the use of innovative processing techniques involving MPCVD deposition conditions and methane (CH4), nitrogen (N2), and hydrogen (H2) chemistry, we have achieved diamond films which consistently adhere to the alloy substrate. In addition, we have discovered that, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well-faceted diamond to nanocrystalline diamond with extremely low surface roughness (as low as 27 nm). The relationship between processing and structure was studied using in-situ optical emission spectroscopy, micro-Raman spectroscopy, surface profilometry, glancing-angle x-ray diffraction, and scanning electron microscopy. We observe that when nitrogen is added to the H2/CH4 feedgas mixture, a carbon-nitrogen (CN) emission band arises and its relative abundance to the carbon dimer (C2) gas species is shown to have a pronounced influence on the diamond film structure. By appropriate choice of deposition chemistry and conditions, we can tailor the diamond film structure and its corresponding properties. The mechanical properties of interest in this thesis are those relating to the integrity of the film/substrate interface, as well as the hardness, wear resistance, residual stress, and elastic modulus of the film. The mechanical properties of the diamond coatings were characterized by indentation and wear testing instruments. Finally, we developed a model based on fundamental thermodynamic and optical principles for extracting the time dependence of film thickness and surface roughness using optical pyrometry for the case of an absorbing substrate. This model provides a convenient way to determine film thickness during growth in CVD systems as well as a reliable estimate of surface roughness.

Catledge, Shane Aaron

381

Formation of ohmic contacts to p-type diamond using carbide forming metals  

NASA Astrophysics Data System (ADS)

The measurement of the specific contact resistance, rho(sub C), and microstructural analysis at the metal/diamond interface were carried out for diamond with various acceptor concentrations, N(sub A), in order to understand the carrier transport mechanism at the metal/diamond interface. The rho(sub C) measurements were carried out for polycrystalline boron-doped semiconducting diamonds which were prepared by the microwave plasma chemical vapor deposition. The acceptor concentrations, estimated by the boron concentrations measured by secondary ion mass spectroscopy, ranged from 3 x 10(exp 18) to 3 x 10(exp 20)/cu cm. Ti and Mo films, which form carbides with diamond, were deposited on the diamonds using the electron-beam evaporation technique. The rho(sub C) values were measured by the cricular transmission line method before and after annealing at temperatures in the range of 400-600 C. The dependence of the rho(sub C) values on the acceptor concentrations suggested that the dominant transport mechanism was the field-emission for the diamond with N(sub A) around 10(exp 20)/cu cm and the thermionic-field-emission for the diamond with N(sub A) from 3 x 10(exp 18)/cu cm to 4 x 10(exp 19)/cu cm. The rho(sub C) values of the Ti contacts were observed to decrease upon annealing, whereas those of the Mo contacts decreased gradually with increasing annealing temperature. However, the rho(sub C) values of both the Ti and Mo contacts reached at the same value of approximately 1 x 10(exp -6) Ohm sq cm after annealing at 600 C for the diamonds with N(sub A) higher than 10(exp 20)/cu cm. Note that the rho(sub C) values of the Mo contact were extremely stable at high temperatures: the rho(sub C) values did not deteriorate after annealing at 600 C for more than 3 h. The thermally stable molybdenum carbide (alpha-Mo2C) and amorphous layers were observed at the Mo/diamond interface after annealing at 600 C by cross-sectional transmission electron microscopy and x-ray diffraction.

Nakanishi, Jiro; Otsuki, A.; Oku, T.; Ishiwata, O.; Murakami, Masanori

1994-08-01

382

Conductive polymer-modified boron-doped diamond for DNA hybridization analysis  

NASA Astrophysics Data System (ADS)

In this paper, we study the immobilization of DNA on boron-doped diamond (BDD) thin films for DNA hybridization analysis. Taking advantage of the conducting nature of the BDD film, a thin layer of polyaniline/poly (acrylic acid) (PANI/PAA) composite polymer film could be readily electropolymerized onto the diamond surface. The carboxylic acid residues in the polymer film act as the binding sites for DNA attachment, whilst the conductive polymer matrix enhances the electron-transfer between DNA and the diamond surface. Fluorescence microscopy and cyclic voltammetry measurements indicate that the polymer-modified BDD has minimal non-specific DNA adsorption, and provides a stable transduction platform for DNA sensing.

Gu, Huiru; Su, Xiaodi; Loh, Kian Ping

2004-04-01

383

Light intensity dependence of photocurrent gain in single-crystal diamond detectors  

NASA Astrophysics Data System (ADS)

The authors report on the photocurrent gain in a diamond photodetector that has two nonohmic contacts connected back-to-back. This photocurrent gain strongly depends on both the deep-ultraviolet (DUV) light intensity and the applied voltage. In addition, the gain is accompanied by a slow response. The gain is observed to originate from a metal/diamond interface trap center. Numerical analysis discloses that the photocurrent-voltage characteristics follow thermionic-field emission tunneling at low DUV light intensity and field-emission tunneling at high DUV light intensity. The deep traps are thought to produce a thin interface barrier layer at the metal/diamond interface under DUV illumination, which is responsible for the tunneling processes.

Liao, Meiyong; Wang, Xi; Teraji, Tokuyuku; Koizumi, Satoshi; Koide, Yasuo

2010-01-01

384

Diamond-like C2H nanolayer, diamane: Simulation of the structure and properties  

NASA Astrophysics Data System (ADS)

We consider a new C2H nanostructure based on bilayer graphene transformed under the covalent bond of hydrogen atoms adsorbed on its external surface, as well as compounds of carbon atoms located opposite each other in neighboring layers. They constitute a “film” of the <111> diamond with a thickness of less than 1 nm, which is called diamane. The energy characteristics and electron spectra of diamane, graphene, and diamond are calculated using the density functional theory and are compared with each other. The effective Young’s moduli and destruction thresholds of diamane and graphene membranes are determined by the molecular dynamics method. It is shown that C2H diamane is more stable than CH graphane, its dielectric “gap” is narrower than the band gap of bulk diamond (by 0.8 eV) and graphane (by 0.3 eV), and is harder and more brittle than the latter.

Chernozatonskii, L. A.; Sorokin, P. B.; Kvashnin, A. G.; Kvashnin, D. G.

2009-09-01

385

Structures of diamond-like phases  

SciTech Connect

The diamond-like phases containing carbon atoms with the same degree of hybridization, which is close to sp{sup 3}, are classified. It is found that twenty such phases can exist, and ten of them are described for the first time. Molecular mechanics and semi-empirical quantum-mechanical methods are used to calculate the geometrically optimized structures of diamond-like phase clusters and to determine their structural parameters and properties, such as the density, the bulk modulus, and the sublimation energy. The difference between the properties of the diamond-like phases and those of diamond is found to be determined by the difference between the structures of these phases and diamond.

Greshnyakov, V. A.; Belenkov, E. A., E-mail: belenkov@csu.ru [Chelyabinsk State University (Russian Federation)

2011-07-15

386

Diamond as an inert substrate of graphene  

SciTech Connect

Interaction between graphene and semiconducting diamond substrate has been examined with large-scale density functional theory calculations. Clean and hydrogenated diamond (100) and (111) surfaces have been studied. It turns out that weak van der Waals interactions dominate for graphene on all these surfaces. High carrier mobility of graphene is almost not affected, except for a negligible energy gap opening at the Dirac point. No charge transfer between graphene and diamond (100) surfaces is detected, while different charge-transfer complexes are formed between graphene and diamond (111) surfaces, inducing either p-type or n-type doping on graphene. Therefore, diamond can be used as an excellent substrate of graphene, which almost keeps its electronic structures at the same time providing the flexibility of charge doping.

Hu Wei; Li Zhenyu; Yang Jinlong [Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2013-02-07

387

Alpha-Voltaic Sources Using Diamond as Conversion Medium  

NASA Technical Reports Server (NTRS)

A family of proposed miniature sources of power would exploit the direct conversion of the kinetic energy of a particles into electricity in diamond semiconductor diodes. These power sources would function over a wide range of temperatures encountered in terrestrial and outer-space environments. These sources are expected to have operational lifetimes of 10 to 20 years and energy conversion efficiencies >35 percent. A power source according to the proposal would include a pair of devices like that shown in the figure. Each device would contain Schottky and p/n diode devices made from high-band-gap, radiation-hard diamond substrates. The n and p layers in the diode portion would be doped sparsely (<1014 cm-3) in order to maximize the volume of the depletion region and thereby maximize efficiency. The diode layers would be supported by an undoped diamond substrate. The source of a particles would be a thin film of 244Cm (half-life 18 years) sandwiched between the two paired devices. The sandwich arrangement would force almost every a particle to go through the active volume of at least one of the devices. Typical a particle track lengths in the devices would range from 20 to 30 microns. The a particles would be made to stop only in the undoped substrates to prevent damage to the crystalline structures of the diode portions. The overall dimensions of a typical source are expected to be about 2 by 2 by 1 mm. Assuming an initial 244Cm mass of 20 mg, the estimated initial output of the source is 20 mW (a current of 20 mA at a potential of 1 V).

Patel, Jagadish U.; Fleurial, Jean-Pierre; Kolawa, Elizabeth

2006-01-01

388

Synthesis of Diamond Films on Molybdenum Substrate Surface by Combustion Flame  

NASA Astrophysics Data System (ADS)

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo2C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.

Takahashi, Mamoru; Kamiya, Osamu; Ohyoshi, Tadashi

389

Diamond-metal contacts: interface barriers and real-time characterization  

NASA Astrophysics Data System (ADS)

A review of diamond-metal contacts is presented with reference to reported values of interfacial potential (Schottky) barriers and their dependence on macroscopic and microscopic properties of the diamond surface, the interface and the metal. No simple model can account for the overall spread of p-diamond barriers, although there are, for certain metals, correlations with metal electronegativity, interface chemistry and diamond surface preparation. Detailed studies are presented for a selected contact (Al—p-diamond) using real-time monitoring during metal growth from sub-nanometre to bulk films and subsequent in situ heating to 1000 °C. This contact, prepared in a clean vacuum environment on characterized single-crystal substrates, provides a case study for a combined in situ electrical and spectroscopic investigation using IV measurements for macroscopic diodes and real-time photoelectron spectroscopy for nanoscale metal films. Band bending during growth leads to a rectifying contact with a measured IV barrier height of 1.05 V and an ideality factor of 1.4. A transition from layered to clustered growth of the metal film is revealed in the real-time measurements and this is confirmed by AFM. For the annealed contact, a direct correlation is revealed by real-time photoemission between the onset of interfacial carbide formation and the change from a rectifying to an ohmic contact at 482 °C.

Evans, D. A.; Roberts, O. R.; Williams, G. T.; Vearey-Roberts, A. R.; Bain, F.; Evans, S.; Langstaff, D. P.; Twitchen, D. J.

2009-09-01

390

Diamond-metal contacts: interface barriers and real-time characterization.  

PubMed

A review of diamond-metal contacts is presented with reference to reported values of interfacial potential (Schottky) barriers and their dependence on macroscopic and microscopic properties of the diamond surface, the interface and the metal. No simple model can account for the overall spread of p-diamond barriers, although there are, for certain metals, correlations with metal electronegativity, interface chemistry and diamond surface preparation. Detailed studies are presented for a selected contact (Al-p-diamond) using real-time monitoring during metal growth from sub-nanometre to bulk films and subsequent in situ heating to 1000?°C. This contact, prepared in a clean vacuum environment on characterized single-crystal substrates, provides a case study for a combined in situ electrical and spectroscopic investigation using IV measurements for macroscopic diodes and real-time photoelectron spectroscopy for nanoscale metal films. Band bending during growth leads to a rectifying contact with a measured IV barrier height of 1.05 V and an ideality factor of 1.4. A transition from layered to clustered growth of the metal film is revealed in the real-time measurements and this is confirmed by AFM. For the annealed contact, a direct correlation is revealed by real-time photoemission between the onset of interfacial carbide formation and the change from a rectifying to an ohmic contact at 482?°C. PMID:21832329

Evans, D A; Roberts, O R; Williams, G T; Vearey-Roberts, A R; Bain, F; Evans, S; Langstaff, D P; Twitchen, D J

2009-09-01

391

Morphology, functionality and molecular conformation study of CVD diamond surfaces functionalised with organic linkers and DNA  

NASA Astrophysics Data System (ADS)

This PhD thesis fits within a joint-venture of physicists and biomedical researchers, aimed at the development of diamond-based DNA sensors. CVD diamond was chosen as the substrate material, because a strong covalent carbon-carbon bond can be created in this case, creating a highly stable platform for reusable biosensors or even for continuous monitoring. Moreover, diamond has favourable properties for sensing based on optical (transparency for a large spectral range) as well as electrical signals (semiconductor, stable in aqueous solutions with a wide potential window). The first specific goal for this thesis within the project was to establish the initial functionalisation of CVD diamond surfaces that would allow for the covalent linking of biomolecules, in casu DNA. This was obtained by UV attachement of omega-unsaturated fatty acid molecules (10-undecenoic acid) followed by the use of the zero-length crosslinker EDC to attach amino-modified DNA. The second goal was to characterise the diamond surfaces extensively with physical and (bio-)chemical methods to check the effectiveness of various surface treatments, and to elucidate the molecular organisation of the obtained linker layers and DNA brushes. Point mutation-sensitivity was achieved with end-point fluorescence as well as a real-time label-free electrical sensor prototype. The conformation of the end-tethered DNA molecules was investigated with spectroscopic ellipsometry.

Wenmackers, Sylvia

392

Theoretical analysis of field emission from a metal diamond cold cathode emitter  

SciTech Connect

Recently, Geis {ital et al.} [J. Vac. Sci. Technol. B {bold 14}, 2060 (1996)] proposed a cold cathode emitter based on a Spindt-type design using a diamond film doped by substitutional nitrogen. The device is characterized by high field emission currents at very low power. Two properties, the rough surface of the metallic injector and the negative electron affinity of the (111) surface of the diamond are essential for its operation. We present a first consistent quantitative theory of the operation of a Geis{endash}Spindt diamond field emitter. Its essential features are predicated on nearly {ital zero-field conditions} in the diamond beyond the depletion layer, {ital quasiballistic transport} in the conduction band, and applicability of a modified {ital Fowler{endash}Nordheim equation} to the transmission of electrons through the Schottky barrier at the metal-diamond interface. Calculated results are in good qualitative and quantitative agreement with the experimental results of Geis {ital et al.} {copyright} {ital 1997 American Vacuum Society.}

Lerner, P.; Cutler, P.H.; Miskovsky, N.M. [Physics Department, Penn State University, State College, Pennsylvania 16802 (United States)] [Physics Department, Penn State University, State College, Pennsylvania 16802 (United States)

1997-03-01

393

Effect of pressure on the Raman spectra of synthetic diamonds with boron impurity  

SciTech Connect

The raman scattering technique is used for studying diamonds with a 0.04-0.1 at % boron impurity under a pressure up to 3 GPa in a chamber with sapphire anvils. The Raman frequency increases linearly with pressure for all samples with pressure coefficients of 2.947 cm{sup -1}/GPa for pure diamond and 3.01 cm{sup -1}/GPa for boron-doped samples. The Raman linewidths remain unchanged for pure diamond and for diamond with a boron concentration of about 0.04 at % and decrease linearly upon an increase in pressure for samples with a boron concentration of about 0.1 at %. The Raman spectra with a line profile corresponding to the Fano resonance do not change qualitatively up to a pressure of 3 GPa. In diamond samples with a boron impurity exceeding 0.1 at %, the boron concentration in the surface layer can be substantially higher than at the center of the sample.

Utyuzh, A. N., E-mail: anatu@ns.hppi.troitsk.ru; Timofeev, Yu. A.; Rakhmanina, A. V. [Russian Academy of Sciences, Vereshchagin Institute of High Pressures (Russian Federation)

2007-04-15

394

Creation of deep blue light emitting nitrogen-vacancy center in nanosized diamond  

SciTech Connect

This paper reports on the formation of complex defect centers related to the N3 center in nanosized diamond by employing plasma immersion and focused ion beam implantation methods. He{sup +} ion implantation into nanosized diamondlayer” was performed with the aim of creating carbon atom vacancies in the diamond structure, followed by the introduction of molecular N{sub 2}{sup +} ion and heat treatment in vacuum at 750?°C to initiate vacancy diffusion. To decrease the sp{sup 2} carbon content of nanosized diamond formed during the implantation processes, a further heat treatment at 450?°C in flowing air atmosphere was used. The modification of the bonding properties after each step of defect creation was monitored by Raman scattering measurements. The fluorescence measurements of implanted and annealed nanosized diamond showed the appearance of an intensive and narrow emission band with fine structures at 2.98?eV, 2.83?eV, and 2.71?eV photon energies.

Himics, L., E-mail: himics.laszlo@wigner.mta.hu; Tóth, S.; Veres, M.; Koós, M. [Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Balogh, Z. [Uzhhorod National University, 88000 Uzhhorod (Ukraine)

2014-03-03

395

Study of diamond film nucleation by ultrasonic seeding in different solutions  

NASA Astrophysics Data System (ADS)

In this study we have investigated diamond nucleation on Si substrates by ultrasonic seeding with different liquid solutions of Ultradispersed Detonation Diamond (UDD) powder in a mixture of metal nano- or microparticles (Ni, Co, Y). The influence of different solutions on nucleation efficiency was investigated. For highlighting nucleation centers and better evaluation of the nucleation process the nucleated samples were moved into a Microwave Plasma Enhanced Chemical Vapor Deposition (MW CVD) reactor and a "short-time" (10 min), then followed by a "long-time" (+1 hour), diamond deposition was performed. The morphology of samples was characterized by Scanning Electron Microscopy (SEM) and the chemical composition of grown diamond layer was investigated by Raman Spectroscopy. From the measurements we found out that microsized metal particles positively influenced nucleation and the uniformity of the deposited diamond thin film. The lowest surface roughness was achieved in the case of nanodiamond powder mixed with Co and Y metal powder. The influence of Ni, Co and Y to the nucleation and early growth stage are discussed.

Varga, Marián; Ižák, Tibor; Kromka, Alexander; Veselý, Marian; Hruška, Karel; Michalka, Miroslav

2012-02-01

396

Mechanical properties of synthetic type IIa diamond crystal  

Microsoft Academic Search

The mechanical behavior of synthetic type IIa diamond has been investigated by the Knoop hardness measurement and observation of the cleavage surfaces. It was clarified that the Knoop hardness in (100)?100? of synthetic diamonds increases with decreasing of the nitrogen impurities concentration, and that the synthetic type IIa diamond, having few nitrogen impurities, has the highest hardness of synthetic diamonds.

H. Sumiya; N. Toda; S. Satoh

1997-01-01

397

Appendix A SIMS profiles of hydrogen and deuterium in diamond  

E-print Network

127 Appendix A SIMS profiles of hydrogen and deuterium in diamond A.1 Introduction A diamond sample ion­beam doping. Impurity levels were profiled as a function of depth from the diamond surface using­type reactor, consisting of a quartz tube with diamond­coated quartz substrate holder. The substrate

Goddard III, William A.

398

Understanding diamond pricing using unconditional quantile regressions Nicolas Vaillant*  

E-print Network

Understanding diamond pricing using unconditional quantile regressions Nicolas Vaillant* François of diamonds and their weight in carats. For this purpose, we use a unique sample of 112,080 certified diamonds collected from www.info-diamond.com during the first week of July 2011. We find substantial differences

Paris-Sud XI, Université de

399

COMPUTER SIMULATION OF THE NUCLEATION OF DIAMOND FROM  

E-print Network

COMPUTER SIMULATION OF THE NUCLEATION OF DIAMOND FROM LIQUID CARBON UNDER EXTREME PRESSURES ANASTASSIA SORKIN #12;COMPUTER SIMULATION OF THE NUCLEATION OF DIAMOND FROM LIQUID CARBON UNDER EXTREME of symbols 2 1 Introduction 4 2 Diamond and other allotropes of carbon 6 2.1 The structure of diamond

Adler, Joan

400

Would Diamond Nanorods Be Stronger than Fullerene Nanotubes?  

E-print Network

Would Diamond Nanorods Be Stronger than Fullerene Nanotubes? Olga Shenderova,, Donald Brenner of literature ab initio data, we show that diamond nanorods would have a brittle fracture force and a zero on the orientation of the diamond nanorod. The energetic stability of diamond nanorods is predicted by molecular

Brenner, Donald W.

401

Magnetically Orchestrated Formation of Diamond at Lower Temperatures and Pressures  

Microsoft Academic Search

Man's curiosity and fascination with diamonds date back to ancient times. The knowledge of the many properties of diamond is recorded during Biblical times. Antoine Lavoisier determined the composition of diamond by burning in O2 to form CO2. With the then existing awareness of graphite as carbon, the race began to convert graphite to diamond. The selective chemical synthesis of

Reginald B. Little; Eric Lochner; Robert Goddard

2005-01-01

402

Mineral inclusions in fibrous diamonds: constraints on cratonic mantle refertilization and diamond formation  

NASA Astrophysics Data System (ADS)

We analyzed mineral microinclusions in fibrous diamonds from the Wawa metaconglomerate (Superior craton) and Diavik kimberlites (Slave craton) and compared them with published compositions of large mineral inclusions in non-fibrous diamonds from these localities. The comparison, together with similar datasets available for Ekati and Koffiefontein kimberlites, suggest a general pattern of metasomatic alteration imposed on the ambient mantle by formation of fibrous diamond. Calcium and Fe enrichment of peridotitic garnet and pyroxenes and Fe enrichment of olivine associated with fibrous diamond-forming fluids contributes to refertilization of the cratonic mantle. Saline—carbonatitic—silicic fluid trapped by fibrous diamonds may represent one of the elusive agents of mantle refertilization. Calcium enrichment of peridotitic garnet and pyroxenes is expected in local mantle segments during fibrous diamond production, as Ca in the carbonatitic fluids is deposited into the surrounding mantle when oxidized carbon is reduced to diamond. Harzburgitic garnet evolves towards Ca-rich compositions even when it interacts with Ca-poor saline fluids. An unusual trend of Mg enrichment to Fo95-98 is observed in some olivine inclusions in Wawa fibrous diamonds. The trend may result from the carbonatitic composition of the fluid that promotes crystallization of magnesian olivine and preferentially oxidizes the fayalite component. We propose a generic model of fibrous and non-fibrous diamond formation from carbonatitic fluids that explains enrichment of the mantle in mafic magmaphile and incompatible elements and accounts for locally metasomatized compositions of diamond inclusions.

Miller, Christine E.; Kopylova, Maya; Smith, Evan

2014-06-01

403

Layers and Layers  

NSDL National Science Digital Library

This lesson has students create their own rock layers by slowly adding and observing how different types of sediment interact when layered upon each other. This lesson is meant to illustrate how we can use these layers to discover the relative age of an object found in that layer by utilizing the Law of Superposition.

Cheri Tremarco

2011-10-07

404

Brine Rich Diamond-Forming Fluids  

NASA Astrophysics Data System (ADS)

Micro-inclusions in diamonds provide pristine information on the composition of mantle fluids. We explored the composition of sub-micrometer inclusions in 12 fibrous diamonds from Diavik, Slave Craton, Canada. TEM investigation of the inclusions revealed a multi-phase halide-carbonate assemblage with minor apatite. Fluid is also present indicating crystallization during cooling from a primary fluid, trapped during the diamond growth. Potassium is concentrated in halide and fluid; no K-bearing carbonates were found. Ten diamonds carry brine-rich fluid with an average composition of K6 Na4CaMgFeBa(Si,Al)O2Cl9.4(CO3)4.3(H2O)10 (determined using EPMA and FTIR). In one zoned diamond carbonatitic melt inclusions populates the rim (K13Na24Ca11Mg22 Fe5Ba2Si7AlP2Cl11); the mantle carries brine (K18Na24Ca6Mg10Fe4Ba3Si5PCl26). One diamond carries composition intermediate between hydro-silicic and carbonatitic melt. The brine in the Canadian diamonds is similar to that found by Izraeli et al. (2001) in cloudy eclogitic and peridotitic diamonds from Koffiefontein, but is richer in Na, Fe and Ba. Micro-inclusions of peridotitic minerals were found in two of the Canadian diamonds. Integrating diamond fluid data from Africa, Brazil, Siberia, and Canada, we found a narrow ranges of fluid composition varying between four end members: hydrous melts rich in silica and alkalis, carbonatitic melts rich in Mg, Fe and Ca, brine rich in Cl, K and Na and sulfide melts rich in Fe and Ni. Carbonatitic melts were found together with all other fluids. The other three components were never detected together in any single diamond and no mixing lines were observed between them. Brine may be generated from parental carbonatitic melts by carbonate crystallization and separation of the residual melt into two immiscible fluids: brine and hydrous-silicic melt. Diamonds can grow from all these fluids. The trace element chemistry of the diamond-forming fluids is similar to that of kimberlites. It is possible that kimberlitic magmas at depth are closer in composition to the trapped fluids and to carbonate and halide-rich fluids recently found in olivine phenocrysts in an Udachnayan kimberlite. The volatile content of erupting kimberlites represents magma that degassed during most of its ascent.

Klein-Bendavid, O.; Wirth, R.; Izraeli, E. S.; Navon, O.

2004-12-01

405

J. Phys. D:Appl. Phys. 25 (1992) 1418-1424. Printed in the UK I Friction of diamond on diamond in  

E-print Network

J. Phys. D:Appl. Phys. 25 (1992) 1418-1424. Printed in the UK I Friction of diamond on diamond, in final form 18June 1992 Abstract. Effectson diamond-diamond friction of ultra-high vacuum (UHV) (-4 x 1O in their molecular and atomic states have been investigated. The friction coefficientfor diamond sliding on diamond

Tzeng, Yonhua

406

JOURNAL OF MATERIALS SCIENCE 31 (1996) 2801 2805 Laser ablation of diamond fibres and a diamond fibre  

E-print Network

modulus values for natural or synthetic diamond grit are greater than those of any other material [1JOURNAL OF MATERIALS SCIENCE 31 (1996) 2801 2805 Laser ablation of diamond fibres and a diamond Research Agency Farnborough, GU14 6TD, UK Continuous chemical vapour-deposited diamond-coated fibres

Bristol, University of

407

Diamond and Related Materials 7 (1998) 14911502 Growth of diamond films using an enclosed methyl-acetylene and  

E-print Network

Diamond and Related Materials 7 (1998) 1491­1502 Growth of diamond films using an enclosed methyl Research Laboratory, Washington, DC, USA Received 20 November 1997; accepted 4 June 1998 Abstract Diamond-stabilized, low pressure, flat, premixed flame was used to deposit continuous, uniform thickness diamond films

Dandy, David

408

Diamond and Related Materials, 3 (1994) 1375-1380 1375 Deposition of diamond films on sapphire: studies of interfacial properties  

E-print Network

Diamond and Related Materials, 3 (1994) 1375- 1380 1375 Deposition of diamond films on sapphire) Abstract Polycrystalline diamond films were grown on single crystal sapphire substrates using hot filament on the sapphire prior to the diamond CVD step. Patterned silicon-on-sapphire wafers were then used as substrates

Bristol, University of

409

Extending Quantum Coherence in Diamond  

E-print Network

We experimentally demonstrate over two orders of magnitude increase in the coherence time of nitrogen vacancy centres in diamond by implementing decoupling techniques. We show that equal pulse spacing decoupling performs just as well as non-periodic Uhrig decoupling and has the additional benefit that it allows us to take advantage of "revivals" in the echo (due to the coherent nature of the bath) to explore the longest coherence times. At short times, we can extend the coherence of particular quantum states out from T_2*=2.7 us out to an effective T_2 > 340 us. For preserving arbitrary states we show the experimental importance of using pulse sequences, that through judicious choice of the phase of the pulses, compensate the imperfections of individual pulses for all input states. At longer times we use these compensated sequences to enhance the echo revivals and show a coherence time of over 1.6 ms in ultra-pure natural abundance 13C diamond.

C. A. Ryan; J. S. Hodges; D. G. Cory

2010-08-18

410

The Geopolitical Setting of Conflict Diamonds.  

NASA Astrophysics Data System (ADS)

September 11, 2001 will live in infamy. Ideological differences have also led to senseless atrocities in Angola, Congo Republic, Sierra Leone, and Liberia. Hundreds of thousands have died, scores mutilated, and millions displaced. These have gone virtually unnoticed for decades. Unnoticed that is until it became evident that these barbaric acts were fueled by the sale or bartering of diamonds for arms, or by more ingenious ways that are less traceable. There is no end in sight. Industry has long recognized that about 20% of diamonds reaching the open market are smuggled from operating mines, and more recently that an additional 4% originates from conflict diamond sources. Diamond identification by laser inscription, ion implantation, or certification protocols are subject to fraudulent tampering. And these applied methods are thwarted if cutting and polishing centers are infiltrated, or if terrorist facilities are independently established. Mark ups are substantial (40-60%) from raw material to finished product. Tracking the paths of rough stones from mines to faceted gems is impractical because some 30-50 million cts of top quality material, or about 100 million stones, would require branding each year. Moreover, the long standing tradition of site-holdings and the bourse system of mixing or matching diamonds, inadvertently ensures regional anonymity. Conflict diamonds are mined in primary kimberlites and from widely dispersed alluvial fields in tropical jungle. Landscapes, eroded by 1-5 vertical km over 100 Ma, have transformed low grade primary deposits into unconsolidated sedimentary bonanzas. The current value of stones retrieved, by motivated diggers and skillful jiggers, in rebel held territories, is impossible to determine, but in 1993 amounted to tens of millions USD. Diamonds over 100 cts continue to surface at premier prices. Borders are porous, diamonds flow easily, and armed networks are permeable and mobile. Diamonds form at great depths (over 200 km) in the Earth's mantle, are old (about 3 Ga), and are emplaced volcanically into continental crust (cratons), at specific times geologically. Clusters of diamond volcanoes are common throughout the world, and in Africa spill over into several countries. Although there are subtle distinctions in geology, geophysics, and geochemistry of diamondiferous settings globally, these differences decrease within provinces (1000 sq km), and are minor at the district level (10-100 sq km). For diamonds: clear, sharp edged octahedra are typical of Siberia; pink stones are mostly from W. Australia; Cape yellow and blue diamonds occur in South Africa and India; corroded and etched diamonds are prevalent in E. Africa; and fibrous diamonds, once considered the domain of the Congo Republic and Sierra Leone were recently discovered in the non conflict, Slave Province, Canada. These examples are neither craton nor site specific. Is there a non destructive analytical method to uniquivocally identify diamonds regionally, or ideally at a more localized level? The intrinsic approach (vs applied) is challenging because geographical boundaries do not correspond to geological contacts. Spectroscopy, trace elements, isotopes, mineral inclusions, and the conductivities of diamonds show some promise but the overlaps are large. Refinements will evolve and analytical innovations will develop. However, legally acquired conflict diamonds are needed on which to perform basic experiments, establish background levels, and develop a data base for global comparisons. US assistance, UN permission, and funding (e.g. NSF, DOD) are urgently required if this geoscientific initiative is to move forward in stopping the flow of conflict diamonds into the hands of terrorist organizations. We have a scientific obligation to society.

Haggerty, S. E.

2002-05-01

411

Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications  

DOEpatents

One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

Gruen, Dieter M. (Downers Grove, IL)

2009-08-11

412

Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications  

DOEpatents

One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

Gruen, Dieter M.

2012-09-04

413

Phosphorylated nano-diamond/ Polyimide Nanocomposites  

NASA Astrophysics Data System (ADS)

In this study, a novel route to synthesize polyimide (PI)/phosphorylated nanodiamond films with improved thermal and mechanical properties was developed. Surface phosphorylation of nano-diamond was performed in dichloromethane. Phosphorylation dramatically enhanced the thermal stability of nano-diamond. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized with 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-oxydianiline (4,4'-ODA) in the solution of N,N- dimethylformamide (DMF). Pure BTDA-ODA polyimide films and phosphorylated nanodiamond containing BTDA-ODA PI films were prepared. The PAA displayed good compatibility with phosphorylated nano-diamond. The morphology of the polyimide (PI)/phosphorylated nano-diamond was characterized by scanning electron microscopy (SEM). Chemical structure of polyimide and polyimide (PI)/phosphorylated nano-diamond was characterized by FTIR. SEM and FTIR results showed that the phosphorylated nano-diamond was successfully prepared. Thermal properties of the polyimide (PI)/phosphorylated nanodiamond was characterized by thermogravimetric analysis (TGA). TGA results showed that the thermal stability of (PI)/phosphorylated nano-diamond film was increased.

Beyler-Çi?il, Asli; Çakmakçi, Emrah; Vezir Kahraman, Memet

2014-08-01

414

UV-Induced Photoconduction in Diamond  

NASA Astrophysics Data System (ADS)

Owing to its physical properties, diamond is a very promising candidate for UV photon detection. The synthesis of very high quality polycrystalline diamond thick films and single crystals is presently accomplished routinely using the chemical vapour deposition (CVD) technique. Metal/diamond/metal ohmic junctions are produced by depositing electrical contacts on the front surface (coplanar contacts) or on both front and back (sandwich contacts). The investigation of diamond properties in the wavelength range 100-300 nm is of considerable interest in order to attain ultraviolet (UV) detectors having high quantum efficiency against no sensitivity to visible photons, along with radiation hardness and chemical inertness. Improvements in diamond synthesis techniques and processing technology now make available very high quality polycrystalline diamond films as well as optical-grade single crystals with dimensions sufficiently large for developing detectors. Several problems limiting the performance have been solved, and single-pixel detectors are close to being suitable for exploitation. This paper reviews the status of the art of diamond-based UV detectors, their application in specific fields, such as excimer lasers, photolithography and space experiments, and the perspectives.

Pace, Emanuele; De Sio, Antonio; Scuderi, Salvatore

415

Dislocation electrical conductivity of synthetic diamond films  

SciTech Connect

A relationship between the electric resistance of single-crystal homoepitaxial and polycrystalline diamond films and their internal structure has been investigated. It is established that the electrical conductivity of undoped homoepitaxial and polycrystalline diamond films is directly related to the dislocation density in them. A relation linking the resistivity {rho} ({approx}10{sup 13}-10{sup 15} {omega} cm) with the dislocation density {gamma} ({approx}10{sup 14}-4 x 10{sup 16} m{sup -2}) is obtained. The character of this correlation is similar for both groups of homoepitaxial and polycrystalline diamond films. Thin ({approx}1-8 {mu}m) homoepitaxial and polycrystalline diamond films with small-angle dislocation boundaries between mosaic blocks exhibit dislocation conductivity. The activation energy of dislocation acceptor centers was calculated from the temperature dependence of the conductivity and was found to be {approx}0.3 eV. The conduction of thick diamond films (h > 10 {mu}m) with the resistivity {rho} {approx} 10{sup 8} {omega} cm is determined by the conduction of intercrystallite boundaries, which have a nondiamond hydrogenated structure. The electronic properties of the diamond films are compared with those of natural semiconductor diamonds of types IIb and Ic, in which dislocation acceptor centers have activation energies in the range 0.2-0.35 eV and are responsible for hole conduction.

Samsonenko, S. N., E-mail: snsamsonenko@mail.ru; Samsonenko, N. D. [Donbass National Academy of Civil Engineering and Architecture (Ukraine)

2009-05-15

416

Progress on diamond amplified photo-cathode  

SciTech Connect

Two years ago, we obtained an emission gain of 40 from the Diamond Amplifier Cathode (DAC) in our test system. In our current systematic study of hydrogenation, the highest gain we registered in emission scanning was 178. We proved that our treatments for improving the diamond amplifiers are reproducible. Upcoming tests planned include testing DAC in a RF cavity. Already, we have designed a system for these tests using our 112 MHz superconducting cavity, wherein we will measure DAC parameters, such as the limit, if any, on emission current density, the bunch charge, and the bunch length. The diamond-amplified photocathode, that promises to support a high average current, low emittance, and a highly stable electron beam with a long lifetime, is under development for an electron source. The diamond, functioning as a secondary emitter amplifies the primary current, with a few KeV energy, that comes from the traditional cathode. Earlier, our group recorded a maximum gain of 40 in the secondary electron emission from a diamond amplifier. In this article, we detail our optimization of the hydrogenation process for a diamond amplifier that resulted in a stable emission gain of 140. We proved that these characteristics are reproducible. We now are designing a system to test the diamond amplifier cathode using an 112MHz SRF gun to measure the limits of the emission current's density, and on the bunch charge and bunch length.

Wang, E.; Ben-Zvi, I.; Burrill, A.; Kewisch, J.; Chang, X.; Rao, T.; Smedley, J.; Wu, Q.; Muller, E.; Xin, T.

2011-03-28

417

Ultradisperse-Diamond Nanoclusters. Fractal Structure and Diamond–Graphite Phase Transition  

Microsoft Academic Search

A systematic study of the diamond–graphite structural phase transition in ultradisperse-diamond clusters obtained by the detonation technique is reported. Samples of two types, differing in the kinetics of detonation-product cooling, were investigated. The phase transition was achieved under heating in an inert atmosphere in the temperature range 720–1400 K. X-ray characterization showed the ultradisperse-diamond, irrespective of the cooling rate used,

M. V. Baidakova; V. I. Siklitsky; A. Ya Vul

1999-01-01

418

Trace element compositions of submicroscopic inclusions in coated diamond: A tool for understanding diamond petrogenesis  

NASA Astrophysics Data System (ADS)

Trace element compositions of submicroscopic inclusions in both the core and the coat of five coated diamonds from the Democratic Republic of Congo (DRC, formerly Zaire) have been analyzed by Laser Ablation Inductively Coupled Mass Plasma Spectrometry (LA-ICP-MS). Both the diamond core and coat inclusions show a general 2-4-fold enrichment in incompatible elements relative to major elements. This level of enrichment is unlikely to be explained by the entrapment of silicate mantle minerals (olivine, garnet, clinopyroxene, phlogopite) alone and thus submicroscopic fluid or glass inclusions are inferred in both the diamond coat and in the gem quality diamond core. The diamond core fluids have elevated High Field Strength Element (Ti, Ta, Zr, Nb) concentrations and are enriched in U relative to inclusions in the diamond coats and relative to chondrite. The core fluids are also moderately enriched in LILE (Ba, Sr, K). Therefore, we suggest that the diamond cores contain inclusions of silicate melt. However, the Ni content and Ni/Fe ratio of the trapped fluid are very high for a silicate melt in equilibrium with mantle minerals; high Ni and Co concentrations in the diamond cores are attributed to the presence of a sulfide phase coexisting with silicate melt in the diamond core inclusions. Inclusions in the diamond coat are enriched in LILE (U, Ba, Sr, K) and La over the diamond core fluids and to chondrite. The coats have incompatible element ratios similar to natural carbonatite (coat fluid: Na/Ba ?0.66, La/Ta?130). The coat fluid is also moderately enriched in HFSE (Ta, Nb, Zr) when normalized to chondritic Al. LILE and La enrichment is related to the presence of a carbonatitic fluid in the diamond coat inclusions, which is mixed with a HFSE-rich hydrous silicate fluid similar to that in the core. The composition of the coat fluid is consistent with a genetic link to group 1 kimberlite.

Tomlinson, Emma; De Schrijver, Isabel; De Corte, Katrien; Jones, Adrian P.; Moens, Luc; Vanhaecke, Frank

2005-10-01

419

Diamond inclusions in garnets from metamorphic rocks: a new environment for diamond formation  

Microsoft Academic Search

DIAMONDS commonly occur in kimberlites, lamproites and alluvial sediments derived from these rocks. More recently, diamonds (or their graphite pseudomorphs) have been discovered in ultramafic massifs1 and picrites2. Here we report the occurrence of diamonds in situ in crustal rocks: highly retrograded high-pressure metamorphic garnet-pyroxene and pyroxene-carbonate-garnet rocks, biotite gneisses and schists from the Kokchetav massif, northern Kazakhstan, USSR. The

N. V. Sobolev; V. S. Shatsky

1990-01-01

420

Epithelial cell morphology and adhesion on diamond films deposited and chemically modified by plasma processes.  

PubMed

The authors show that nanocrystalline diamond (NCD) thin films prepared by microwave plasma enhanced chemical vapor deposition apparatus with a linear antenna delivery system are well compatible with epithelial cells (5637 human bladder carcinoma) and significantly improve the cell adhesion compared to reference glass substrates. This is attributed to better adhesion of adsorbed layers to diamond as observed by atomic force microscopy (AFM) beneath the cells. Moreover, the cell morphology can be adjusted by appropriate surface treatment of diamond by using hydrogen and oxygen plasma. Cell bodies, cytoplasmic rims, and filopodia were characterized by Peakforce AFM. Oxidized NCD films perform better than other substrates under all conditions (96% of cells adhered well). A thin adsorbed layer formed from culture medium and supplemented with fetal bovine serum (FBS) covered the diamond surface and played an important role in the cell adhesion. Nevertheless, 50-100 nm large aggregates formed from the RPMI medium without FBS facilitated cell adhesion also on hydrophobic hydrogenated NCD (increase from 23% to 61%). The authors discuss applicability for biomedical uses. PMID:25280853

Rezek, Bohuslav; Ukraintsev, Egor; Krátká, Marie; Taylor, Andrew; Fendrych, Frantisek; Mandys, Vaclav

2014-09-01

421

Formation of C-N compounds by N-implantation into diamond films  

NASA Astrophysics Data System (ADS)

Diamond films were implanted with 50-110 keV N ions to the dosage of 1 × 10 17 ions/cm 2 at the temperature below 80°C. The possibility of the formation of C-N compounds in diamond films was investigated by means of X-ray photoelectron spectroscopy (XPS) scanning electron microscope (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared absorption spectroscopy (FTIR) and Raman spectroscopy. For the first time, the new evidence about the formation of plenty of C-N single bonds which is necessary for ?-C 3N 4 formation in the diamond films has been presented. It is found that the low energy ion was suitable for the formation of C-N compound. The XPS analysis indicate that both C and N form three types of chemical states. FTIR and Raman spectra show that a large number of the C-N covalent bond have been formed. XRD and Raman analysis indicate that the structure of implanted layer is amorphous. The electrical resistivity in the implanted layer exhibits diamond-like property.

Xie, E. Q.; Jin, Y. F.; Wang, Z. G.; He, D. Y.

1998-02-01

422

Bonding Diamond To Metal In Electronic Circuits  

NASA Technical Reports Server (NTRS)

Improved technique for bonding diamond to metal evolved from older technique of soldering or brazing and more suitable for fabrication of delicate electronic circuits. Involves diffusion bonding, developed to take advantage of electrically insulating, heat-conducting properties of diamond, using small diamond bars as supports for slow-wave transmission-line structures in traveling-wave-tube microwave amplifiers. No fillets or side coats formed because metal bonding strips not melted. Technique also used to mount such devices as transistors and diodes electrically insulated from, but thermally connected to, heat sinks.

Jacquez, Andrew E.

1993-01-01

423

First principles study of Fe in diamond: A diamond-based half metallic dilute magnetic semiconductor  

SciTech Connect

Half-metallic ferromagnetic ordering in semiconductors, essential in the emerging field of spintronics for injection and transport of highly spin polarised currents, has up to now been considered mainly in III–V and II–VI materials. However, low Curie temperatures have limited implementation in room temperature device applications. We report ab initio Density Functional Theory calculations on the properties of Fe in diamond, considering the effects of lattice site, charge state, and Fermi level position. We show that the lattice sites and induced magnetic moments of Fe in diamond depend strongly on the Fermi level position and type of diamond co-doping, with Fe being energetically most favorable at the substitutional site in p-type and intrinsic diamond, while it is most stable at a divacancy site in n-type diamond. Fe induces spin polarized bands in the band gap, with strong hybridization between Fe-3d and C-2s,2p bands. We further consider Fe-Fe spin interactions in diamond and show that substitutional Fe{sup +1} in p-type diamond exhibits a half-metallic character, with a magnetic moment of 1.0??{sub B} per Fe atom and a large ferromagnetic stabilization energy of 33?meV, an order of magnitude larger than in other semiconductors, with correspondingly high Curie temperatures. These results, combined with diamond's unique properties, demonstrate that Fe doped p-type diamond is likely to be a highly suitable candidate material for spintronics applications.

Benecha, E. M. [Department of Physics, University of South Africa, P.O. Box 392, UNISA 0003 Pretoria (South Africa); Lombardi, E. B., E-mail: lombaeb@unisa.ac.za [College of Graduate Studies, University of South Africa, P.O. Box 392, UNISA 0003 Pretoria (South Africa)

2013-12-14

424

Electrons diffusion study on the nitrogen-doped nanocrystalline diamond film grown by MPECVD method  

NASA Astrophysics Data System (ADS)

Nitrogen-doped nanocrystalline diamond (NNCD) films were deposited onto p-type silicon substrates with three different layer structures: (i) directly onto the silicon substrate (NNCD/Si), (ii) silicon with undoped nanocrystalline diamond layer which was deposited in the same way as the above mentioned NNCD by the recipe Ar/CH 4/H 2 with a ratio of 98%/1%/1% (NNCD/NCD/Si), and (iii) silicon wafer with 100 nm thickness SiO 2 layer (NNCD/SiO 2/Si). Atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy were employed to characterize the morphology and microstructure of the as-grown nitrogen-doped diamond films. Silver colloid/silver contacts were made at to measure the current-voltage ( I- V) characteristics for the three different structures. Electrons from a CVD reactor hydrogen plasma diffuse toward the p-type silicon substrate during a deposition process under the high temperature (˜800 °C). The study concluded that the SiO 2 layer could effectively prevents the diffusion of electrons.

Hu, Qiang; Joshi, Rakesh K.; Kumar, Ashok

2010-08-01

425

Multifrequency spin resonance in diamond  

SciTech Connect

Magnetic resonance techniques provide a powerful tool for controlling spin systems, with applications ranging from quantum information processing to medical imaging. Nevertheless, the behavior of a spin system under strong excitation remains a rich dynamical problem. In this paper, we examine spin resonance of the nitrogen-vacancy center in diamond under conditions outside the regime where the usual rotating-wave approximation applies, focusing on effects of multifrequency excitation and excitation with orientation parallel to the spin quantization axis. Strong-field phenomena such as multiphoton transitions and coherent destruction of tunneling are observed in the spectra and analyzed via numerical and analytic theory. In addition to illustrating the response of a spin system to strong multifrequency excitation, these observations may inform techniques for manipulating electron-nuclear spin quantum registers.

Childress, Lilian; McIntyre, Jean [Department of Physics and Astronomy, Bates College, 44 Campus Ave, Lewiston, Maine 04240 (United States)

2010-09-15

426

Quantum information processing in diamond  

E-print Network

Quantum computing is an attractive and multidisciplinary field, which became a focus for experimental and theoretical research during last decade. Among other systems, like ions in traps or superconducting circuits, solid-states based qubits are considered to be promising candidates for first experimental tests of quantum hardware. Here we report recent progress in quantum information processing with point defect in diamond. Qubits are defined as single spin states (electron or nuclear). This allows exploring long coherence time (up to seconds for nuclear spins at cryogenic temperatures). In addition, the optical transition between ground and excited electronic states allows coupling of spin degrees of freedom to the state of the electromagnetic field. Such coupling gives access to the spin state readout via spin-selective scattering of photon. This also allows using of spin state as robust memory for flying qubits (photons).

F. Jelezko; J. Wrachtrup

2005-10-19

427

Diamond deposition at low substrate temperatures  

NASA Astrophysics Data System (ADS)

Three different experimental approaches are reported for the deposition of diamond at low substrate temperatures. These are a remote thermal CVD technique and two different means for achieving remote microwave plasma enhanced CVD. Using these approaches, it has been shown that diamond can be deposited at low temperatures and on potentially reactive substrates, such as fused silica. In addition, it is shown that the presence of the substrate within a plasma discharge or immediately adjacent to a hot refractory metal surface is not a prerequisite for the crystallization of diamond from hydrocarbon-hydrogen mixtures. Well crystallized as well as nanocrystalline diamond coatings were obtained at substrate temperatures as low as 430 to 450 C.

Yarbrough, W. A.; Badzian, A. R.; Pickrell, D.; Liou, Y.; Inspektor, A.

1990-01-01

428

Ultrasensitive Magnetometry and Imaging with NV Diamond  

E-print Network

three techniques are explored: (1) Electron paramagnetic resonance (EPR) imaging with microwave field gradients, (2) Magic angle rotation of magnetic field, and (3) TEM irradiation to optimize the yield of NV in a diamond. For the EPR imaging...

Kim, Changdong

2011-08-08

429

Optical properties of diamond at elevated temperatures  

SciTech Connect

The unique multispectral transparency properties of diamond, combined with its chemical inertness, hardness, and mechanical strength, enable a variety of optical applications requiring infrared transparency in aggressive environments. Knowledge of the optical properties of diamond at elevated temperatures enables the use of Fizeau interferometry as an in situ, non-contact probe of temperature, for homoepitaxial diamond growth studies, for example, and may be useful for other applications as well. The temperature dependence of the index of refraction of type IIa natural diamond was determined by Fizeau interferometry using a HeNe laser. Subtracting the contribution of thermal expansion to the optical path length, the logarithmic temperature derivative of the refractive index, 1/n dn/dT, is found to rise from 4 x 10{sup -6} at room temperature to 2.0 x 10{sup -5} at 1200 {degrees}C at a wavelength of 633 nm.

Rawles, R.E. [Rice Univ., Houston, TX (United States); D`Evelyn, M.P. [Rensselaer Polytechnic Institute, Troy, NY (United States)

1995-12-31

430

Diamond coated silicon field emitter array  

SciTech Connect

Diamond coated silicon tip arrays, with and without a self-aligned gate, were fabricated, and current-voltage characteristics of 400 tips were measured. Diamond films were grown uniformly on Si tips using microwave plasma after nucleation with 10 nm diamond suspension and substrate bias. An emission current of 57 ?A was obtained at 5 V from the ungated array tips separated from an anode at 2 ?m. In the case of the gated arrays with 1.5 ?m aperture, an emission current of 3.4 ?A was measured at a gate voltage of 80 V for an anode separation of 200 ?m. The turn-on voltages for these two types of devices were 0.2 and 40 V, respectively. Diamond coated Si tip arrays have potential applications in field emission based low voltage vacuum electronic devices and microsensors.

S. Albin; W. Fu; A. Varghese; A. C. Lavarias; G. R. Myneni

1999-07-01

431

Corticosteroid Therapy for Diamond Blackfan Anemia  

MedlinePLUS

... DBA-NURSE DBA Fact Sheet CortiCosteroid t herapy (prednisone , p rednisolone ) Information for people with Diamond Blackfan ... help the body make more red blood cells. Steroids are also used to stop allergic reactions and ...

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