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1

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

2

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

3

Ultrananocrystalline diamond for electronic applications  

Microsoft Academic Search

Ultrananocrystalline diamond is a unique form of carbon with grain sizes in the 3–5 nm region. This nanostructure has profound implications on electronic transport, as ?10% of carbon is at the grain boundaries. Thus, this material has significant ? bonding which governs the majority of the electrical conductivity due to the lower energy gap of ?–?* transitions relative to ?–?*

O A Williams

2006-01-01

4

Fracture paths and ultrananocrystalline diamond  

Microsoft Academic Search

We use the simulated fracture of ultrananocrystalline diamond (UNCD) to illustrate how different fracture paths can result in different predictions of system properties. At zero temperature, the system is unable to explore the potential energy surface far from the fracture path being investigated. This can result in misleading predictions for the mechanical properties of UNCD. In non-zero temperature simulations, the

Jeffrey T. Paci; Lipeng Sun; Ted Belytschko; George C. Schatz

2005-01-01

5

Nanopatterning of ultrananocrystalline diamond nanowires  

NASA Astrophysics Data System (ADS)

We report the fabrication of horizontally aligned ultrananocrystalline diamond (UNCD) nanowires (NWs) via two different approaches. First, with the top-down approach by using electron beam lithography (EBL) and reactive ion etching (RIE) with a photo resist layer as an etch mask. Using this approach, we demonstrate fabrication of 50 µm long UNCD NWs with widths as narrow as 40 nm. We further present an alternative approach to grow UNCD NWs at pre-defined positions through a selective seeding process. No RIE was needed either to etch the NWs or to remove the mask. In this case, we achieved UNCD NWs with lengths of 50 µm and smallest width of 90 nm respectively. Characterization of these nanowires by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows that the UNCD NWs are well defined and fully released, with no indication of residual stress. Characterization using visible and ultraviolet (UV) Raman spectroscopy indicates that in both fabrication approaches, UNCD NWs maintain their intrinsic diamond structure.

Wang, Xinpeng; Ocola, Leonidas E.; Divan, Ralu S.; Sumant, Anirudha V.

2012-02-01

6

Nanopatterning of ultrananocrystalline diamond nanowires.  

PubMed

We report the fabrication of horizontally aligned ultrananocrystalline diamond (UNCD) nanowires (NWs) via two different approaches. First, with the top-down approach by using electron beam lithography (EBL) and reactive ion etching (RIE) with a photo resist layer as an etch mask. Using this approach, we demonstrate fabrication of 50 µm long UNCD NWs with widths as narrow as 40 nm. We further present an alternative approach to grow UNCD NWs at pre-defined positions through a selective seeding process. No RIE was needed either to etch the NWs or to remove the mask. In this case, we achieved UNCD NWs with lengths of 50 µm and smallest width of 90 nm respectively. Characterization of these nanowires by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows that the UNCD NWs are well defined and fully released, with no indication of residual stress. Characterization using visible and ultraviolet (UV) Raman spectroscopy indicates that in both fabrication approaches, UNCD NWs maintain their intrinsic diamond structure. PMID:22261094

Wang, Xinpeng; Ocola, Leonidas E; Divan, Ralu S; Sumant, Anirudha V

2012-01-20

7

Freestanding ultrananocrystalline diamond films with homojunction insulating layer on conducting layer and their high electron field emission properties.  

PubMed

Freestanding ultrananocrystalline diamond (UNCD) films with homojunction insulating layer in situ grown on a conducting layer showed superior electron field emission (EFE) properties. The insulating layer of the films contains large dendrite type grains (400-600 nm in size), whereas the conducting layer contains nanosize equi-axed grains (5-20 nm in size) separated by grain boundaries of about 0.5-1 nm in width. The conducting layer possesses n-type (or semimetallic) conductivity of about 5.6 × 10(-3) (? cm)(-1), with sheet carrier concentration of about 1.4 × 10(12) cm(-2), which is ascribed to in situ doping of Li-species from LiNbO(3) substrates during growth of the films. The conducting layer intimately contacts the bottom electrodes (Cu-foil) by without forming the Schottky barrier, form homojunction with the insulating layer that facilitates injection of electrons into conduction band of diamond, and readily field emitted at low applied field. The EFE of freestanding UNCD films could be turned on at a low field of E(0) = 10.0 V/?m, attaining EFE current density of 0.2 mA/cm(2) at an applied field of 18.0 V/?m, which is superior to the EFE properties of UNCD films grown on Si substrates with the same chemical vapor deposition (CVD) process. Such an observation reveals the importance in the formation of homojunction on enhancing the EFE properties of materials. The large grain granular structure of the freestanding UNCD films is more robust against harsh environment and shows high potential toward diamond based electronic applications. PMID:21942707

Thomas, Joseph P; Chen, Huang-Chin; Tai, Nyan-Hwa; Lin, I-Nan

2011-10-06

8

Electrical contacts to ultrananocrystalline diamond.  

SciTech Connect

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.; Carlisle, J. A.; Alphenaar, B. W.; Materials Science Division; Univ. of Louisville

2003-09-08

9

Thermomechanical stability of ultrananocrystalline diamond  

NASA Astrophysics Data System (ADS)

We have measured mechanical stiffness and dissipation in ultrananocrystalline diamond (UNCD) from 63 K to 450 K using microcantilever resonators in a custom ultrahigh vacuum (UHV) atomic force microscope. UNCD exhibits a temperature coefficient of modulus that is found to be extremely low: -26 ppm/K, which is close to the previously measured value of -24 ppm/K for single crystal diamond. The magnitude and the temperature dependence of dissipation are consistent with the behavior of disordered systems. The results indicate that defects, most likely at the grain boundaries, create the dominant contribution to mechanical dissipation. These measurements of modulus and dissipation versus temperature in this temperature range in UNCD establish the nanostructure's effect on the thermomechanical stability and suggest routes for tailoring these properties.

Adiga, Vivekananda P.; Suresh, Sampath; Datta, Arindom; Carlisle, John A.; Carpick, Robert W.

2012-03-01

10

Synthesis, Properties and Applications of Ultrananocrystalline Diamond  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) is one of the important triad of nanostructured carbons which includes fullerenes and nanotubes. This new kind of diamond composed of 3-5 nm crystallites is an exemplar par excellence of the profound changes in properties that can accompany the reduction in size of a material to low single digit nanometer dimensions. UNCD occurs in two forms: as

Dieter M. Gruen; Olga A. Shenderova; Alexander Ya. Vul

2005-01-01

11

Transparent ultrananocrystalline diamond films on quartz substrate  

Microsoft Academic Search

Highly transparent ultrananocrystalline diamond (UNCD) films were deposited on quartz substrates using microwave plasma enhanced chemical vapor deposition (MPECVD) method. Low temperature growth of high quality transparent UNCD films was achieved by without heating the substrates prior to the deposition. Additionally, a new method to grow NCD and microcrystalline diamond (MCD) films on quartz substrates has been proposed. Field emission

P. T. Joseph; Nyan-Hwa Tai; Yi-Chun Chen; Hsiu-Fung Cheng; I-Nan Lin

2008-01-01

12

Ultrananocrystalline diamond prepared by pulsed laser deposition  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) and sp2 amorphous carbon composite thin films were grown on sapphire (0001) substrates heated to 550 °C in 4 Torr hydrogen by pulsed laser deposition (PLD) using a graphite target. Transmission electron microscopy revealed that the deposited films consisted of dense non-oriented UNCDs with diameters of approximately 5 nm. The central area of the film, corresponding to

Takeshi Hara; Tsuyoshi Yoshitake; Tomohito Fukugawa; Hironori Kubo; Masaru Itakura; Noriyuki Kuwano; Yoshitsugu Tomokiyo; Kunihito Nagayama

2006-01-01

13

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

14

Ultrananocrystalline Diamond Films from Fullerene Precursors  

Microsoft Academic Search

Fullerenes are unique sources of carbon vapor. The molecule C60 has an equivalent carbon vapor pressure near to 1 Torr at the very modest temperature of 600 C. Fragmentation produces primarily\\u000a carbon dimer C2, resulting in highly supersaturated carbon vapor, which condenses, surprisingly, to form ultrananocrystalline diamond films.\\u000a This new form of diamond (3–5 nm crystallite size) is phase-pure as

Dieter M. Gruen

2001-01-01

15

Bonding structure in nitrogen doped ultrananocrystalline diamond  

Microsoft Academic Search

The transport properties of diamond thin films are well known to be sensitive to the sp2\\/sp3-bonded carbon ratio, the presence of the grain boundaries and other defects, and to the presence of various impurities. In order to clarify the roles these factors play in the conduction mechanisms of nitrogen-doped ultrananocrystalline diamond (UNCD), Raman scattering, near edge x-ray absorption fine structure

James Birrell; J. E. Gerbi; O. Auciello; J. M. Gibson; D. M. Gruen; J. A. Carlisle

2003-01-01

16

Low temperature growth of ultrananocrystalline diamond  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films were prepared by microwave plasma chemical vapor deposition using argon-rich Ar\\/CH4 plasmas at substrate temperatures from ~400 to 800 °C. Different seeding processes were employed to enhance the initial nucleation density for UNCD growth to about 1011 sites\\/cm2. High-resolution transmission electron microscopy, near-edge x-ray absorption fine structure, visible and ultraviolet Raman spectroscopy, and scanning electron microscopy

X. Xiao; J. Birrell; J. E. Gerbi; O. Auciello; J. A. Carlisle

2004-01-01

17

Electron field emission for ultrananocrystalline diamond films  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films 0.1-2.4 mum thick were conformally deposited on sharp single Si microtip emitters, using microwave CH4-Ar plasma-enhanced chemical vapor deposition in combination with a dielectrophoretic seeding process. Field-emission studies exhibited stable, extremely high (60-100 muA\\/tip) emission current, with little variation in threshold fields as a function of film thickness or Si tip radius. The electron emission properties

A. R. Krauss; O. Auciello; M. Q. Ding; D. M. Gruen; Y. Huang; V. V. Zhirnov; E. I. Givargizov; A. Breskin; R. Chechen; E. Shefer; V. Konov; S. Pimenov; A. Karabutov; A. Rakhimov; N. Suetin

2001-01-01

18

Optical characterization of ultrananocrystalline diamond films  

Microsoft Academic Search

Optical properties of the ultrananocrystalline diamond films were studied by multi-sample method based on the combination of variable angle spectroscopic ellipsometry and spectroscopic reflectometry applied in the range 0.6–6.5 eV. The films were deposited by PECVD in a conventional bell jar (ASTeX type) reactor using dual frequency discharge, microwave cavity plasma and radio frequency plasma inducing dc self-bias at a substrate

Daniel Franta; Lenka Zají?ková; Monika Karásková; Ond?ej Jašek; David Ne?as; Petr Klapetek; Miroslav Valtr

2008-01-01

19

Temperature Dependence of Mechanical Stiffness and Dissipation in Ultrananocrystalline Diamond.  

National Technical Information Service (NTIS)

Ultrananocrystalline diamond (UNCD) films are promising for radio frequency micro electro mechanical systems (RF-MEMS) resonators due to the extraordinary physical properties of diamond, such as high Young's modulus, quality factor, and stable surface che...

A. V. Sumant C. Gudeman O. Auciello S. Suresh V. P. Adiga

2009-01-01

20

Nuclear magnetic resonance study of ultrananocrystalline diamonds  

Microsoft Academic Search

.   \\u000a We report on a nuclear magnetic resonance (NMR) study of \\u000a ultrananocrystalline diamond (UNCD) materials produced by detonation \\u000a technique. Analysis of the 13C and 1H NMR spectra, spin-spin and \\u000a spin-lattice relaxation times in purified UNCD samples is presented. Our \\u000a measurements show that UNCD particles consist of a diamond core that is \\u000a partially covered by a sp\\u000a 2-carbon fullerene-like shell. The

A. M. Panich; A. I. Shames; H.-M. Vieth; E. ?sawa; M. Takahashi

2006-01-01

21

Effects of pretreatment processes on improving the formation of ultrananocrystalline diamond  

Microsoft Academic Search

Effects of pretreatment on the nuclei formation of ultrananocrystalline diamond (UNCD) on Si substrates were studied. Either precoating a thin layer of titanium (~400 nm) or ultrasonication pretreatment using diamond and titanium mixed powder (D&T process) enhances the nucleation process on Si substrates markedly, and the UNCD nuclei formed and fully covered the Si substrate, when deposition was processed using

Li-Ju Chen; Nyan-Hwa Tai; Chi-Young Lee; I.-Nan. Lin

2007-01-01

22

Surface functionalization of ultrananocrystalline diamond using atom transfer radical polymerization (ATRP) initiated by electro-grafted aryldiazonium salts  

Microsoft Academic Search

The integration of organic adlayers with diamond surfaces imparts many new properties to diamond materials, including lubrication, optical response, chemical sensing, and biocompatibility. The development of new immobilization chemistries is required in which organic layers are covalently attached to the diamond surface. Poly(methyl methacrylate) and polystyrene brushes (PMMA, PS, respectively) were grown from the surfaces of ultrananocrystalline diamond (UNCD) thin

T. Matrab; M. M. Chehimi; J. P. Boudou; F. Benedic; J. Wang; N. N. Naguib; J. A. Carlisle

2006-01-01

23

Mechanical Stiffness and Dissipation in Ultrananocrystalline Diamond Microresonators.  

National Technical Information Service (NTIS)

We have characterized mechanical properties of ultrananocrystalline diamond UNCD thin films grown using the hot filament chemical vapor deposition HFCVD technique at 680 degrees C, significantly lower than the conventional growth temperature of 800 degree...

A. V. Sumant C. Gudeman O. Auciello S. Suresh V. P. Adiga

2009-01-01

24

Transport properties of n-type ultrananocrystalline diamond films  

Microsoft Academic Search

We investigate transport properties of ultrananocrystalline diamond films for\\u000aa broad range of temperatures. Addition of nitrogen during plasma-assisted\\u000agrowth increases the conductivity of ultrananocrystalline diamond films by\\u000aseveral orders of magnitude. We show that films produced at low concentration\\u000aof nitrogen in the plasma are very resistive and electron transport occurs via\\u000aa variable range hopping mechanism while in

I. S. Beloborodov; P. Zapol; D. M. Gruen; L. A. Curtiss

2006-01-01

25

Electron field emission for ultrananocrystalline diamond films  

SciTech Connect

Ultrananocrystalline diamond (UNCD) films 0.1--2.4 {mu}m thick were conformally deposited on sharp single Si microtip emitters, using microwave CH{sub 4}--Ar plasma-enhanced chemical vapor deposition in combination with a dielectrophoretic seeding process. Field-emission studies exhibited stable, extremely high (60--100 {mu}A/tip) emission current, with little variation in threshold fields as a function of film thickness or Si tip radius. The electron emission properties of high aspect ratio Si microtips, coated with diamond using the hot filament chemical vapor deposition (HFCVD) process were found to be very different from those of the UNCD-coated tips. For the HFCVD process, there is a strong dependence of the emission threshold on both the diamond coating thickness and Si tip radius. Quantum photoyield measurements of the UNCD films revealed that these films have an enhanced density of states within the bulk diamond band gap that is correlated with a reduction in the threshold field for electron emission. In addition, scanning tunneling microscopy studies indicate that the emission sites from UNCD films are related to minima or inflection points in the surface topography, and not to surface asperities. These data, in conjunction with tight binding pseudopotential calculations, indicate that grain boundaries play a critical role in the electron emission properties of UNCD films, such that these boundaries: (a) provide a conducting path from the substrate to the diamond--vacuum interface, (b) produce a geometric enhancement in the local electric field via internal structures, rather than surface topography, and (c) produce an enhancement in the local density of states within the bulk diamond band gap.

Krauss, A. R.; Auciello, O.; Ding, M. Q.; Gruen, D. M.; Huang, Y.; Zhirnov, V. V.; Givargizov, E. I.; Breskin, A.; Chechen, R.; Shefer, E. (and others)

2001-03-01

26

Electronic properties of ultrananocrystalline diamond surfaces.  

SciTech Connect

We have characterized ultrananocrystalline diamond films with different surface terminations by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The surface terminations were performed by plasma functionalization in atmospheres of hydrogen, fluorine, and oxygen. XPS proves the dense monolayer coverage of the surface functionalization. AFM and STM show low impact of the plasma treatment on the surface morphology. STS has been used to investigate the surface electronic properties, for H-terminated surfaces the electronic structure is dominated by the sp{sup 3} carbon phase of the grain surfaces; for O- and F-terminated surfaces, however, sp{sup 2} carbon from the grain boundaries seems to determine the surface band gap.

Lud, S. Q.; Niedermeier, M.; Koch, P. S.; Bruno, P.; Gruen, D. M.; Stutzmann, M.; Garriod, J. A.; Materials Science Division; Technische Univ. Munchen

2010-03-04

27

Electronic properties of ultrananocrystalline diamond surfaces  

NASA Astrophysics Data System (ADS)

We have characterized ultrananocrystalline diamond films with different surface terminations by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The surface terminations were performed by plasma functionalization in atmospheres of hydrogen, fluorine, and oxygen. XPS proves the dense monolayer coverage of the surface functionalization. AFM and STM show low impact of the plasma treatment on the surface morphology. STS has been used to investigate the surface electronic properties, for H-terminated surfaces the electronic structure is dominated by the sp3 carbon phase of the grain surfaces; for O- and F-terminated surfaces, however, sp2 carbon from the grain boundaries seems to determine the surface band gap.

Lud, Simon Q.; Niedermeier, Martin; Koch, Philipp S.; Bruno, Paola; Gruen, Dieter M.; Stutzmann, Martin; Garrido, Jose A.

2010-03-01

28

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

29

Temperature dependence of mechanical stiffness and dissipation in ultrananocrystalline diamond  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films are promising for radio frequency micro electro mechanical systems (RF-MEMS) resonators due to the extraordinary physical properties of diamond, such as high Young's modulus, quality factor, and stable surface chemistry. UNCD films used for this study are grown on 150 mm silicon wafers using hot filament chemical vapor deposition (HFCVD) at 680°C. UNCD fixed free (cantilever)

V. P. Adiga; A. V. Sumant; S. Suresh; C. Gudeman; O. Auciello; J. A. Carlisle

2009-01-01

30

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

31

Ultrananocrystalline diamond thin films functionalized with therapeutically active collagen networks  

Microsoft Academic Search

The fabrication of biologically amenable interfaces in medicine bridges translational technologies with their surrounding biological environment. Functionalized nanomaterials catalyze this coalescence through the creation of biomimetic and active substrates upon which a spectrum of therapeutic elements can be delivered to adherent cells to address biomolecular processes in cancer, inflammation, etc. Here, we demonstrate the robust functionalization of ultrananocrystalline diamond (UNCD)

Houjin Huang; Mark Chen; Paola Bruno; Robert Lam; Erik Robinson; Dieter Gruen; Dean Ho

2009-01-01

32

Thermal conductivity of nitrogenated ultrananocrystalline diamond films on silicon  

Microsoft Academic Search

The authors report on the experimental investigation of the thermal conductivity of nitrogenated ultrananocrystalline diamond (UNCD) films on silicon. For better accuracy, the thermal conductivity was measured by using two different approaches: the 3omega method and transient ``hot disk'' technique. The temperature dependence of the thermal conductivity of the nitrogenated UNCD films was compared to that of undoped UNCD films

M. Shamsa; S. Ghosh; I. Calizo; V. Ralchenko; A. Popovich; A. A. Balandin

2008-01-01

33

Ultra-nanocrystalline diamond electrodes: optimization towards neural stimulation applications  

NASA Astrophysics Data System (ADS)

Diamond is well known to possess many favourable qualities for implantation into living tissue including biocompatibility, biostability, and for some applications hardness. However, conducting diamond has not, to date, been exploited in neural stimulation electrodes due to very low electrochemical double layer capacitance values that have been previously reported. Here we present electrochemical characterization of ultra-nanocrystalline diamond electrodes grown in the presence of nitrogen (N-UNCD) that exhibit charge injection capacity values as high as 163 µC cm-2 indicating that N-UNCD is a viable material for microelectrode fabrication. Furthermore, we show that the maximum charge injection of N-UNCD can be increased by tailoring growth conditions and by subsequent electrochemical activation. For applications requiring yet higher charge injection, we show that N-UNCD electrodes can be readily metalized with platinum or iridium, further increasing charge injection capacity. Using such materials an implantable neural stimulation device fabricated from a single piece of bio-permanent material becomes feasible. This has significant advantages in terms of the physical stability and hermeticity of a long-term bionic implant.

Garrett, David J.; Ganesan, Kumaravelu; Stacey, Alastair; Fox, Kate; Meffin, Hamish; Prawer, Steven

2012-02-01

34

Ultra-nanocrystalline diamond electrodes: optimization towards neural stimulation applications.  

PubMed

Diamond is well known to possess many favourable qualities for implantation into living tissue including biocompatibility, biostability, and for some applications hardness. However, conducting diamond has not, to date, been exploited in neural stimulation electrodes due to very low electrochemical double layer capacitance values that have been previously reported. Here we present electrochemical characterization of ultra-nanocrystalline diamond electrodes grown in the presence of nitrogen (N-UNCD) that exhibit charge injection capacity values as high as 163 µC cm(-2) indicating that N-UNCD is a viable material for microelectrode fabrication. Furthermore, we show that the maximum charge injection of N-UNCD can be increased by tailoring growth conditions and by subsequent electrochemical activation. For applications requiring yet higher charge injection, we show that N-UNCD electrodes can be readily metalized with platinum or iridium, further increasing charge injection capacity. Using such materials an implantable neural stimulation device fabricated from a single piece of bio-permanent material becomes feasible. This has significant advantages in terms of the physical stability and hermeticity of a long-term bionic implant. PMID:22156061

Garrett, David J; Ganesan, Kumaravelu; Stacey, Alastair; Fox, Kate; Meffin, Hamish; Prawer, Steven

2011-12-07

35

Origin of ultralow friction and wear in ultrananocrystalline diamond.  

PubMed

The impressively low friction and wear of diamond in humid environments is debated to originate from either the stability of the passivated diamond surface or sliding-induced graphitization/rehybridization of carbon. We find ultralow friction and wear for ultrananocrystalline diamond surfaces even in dry environments, and observe negligible rehybridization except for a modest, submonolayer amount under the most severe conditions (high load, low humidity). This supports the passivation hypothesis, and establishes a new regime of exceptionally low friction and wear for diamond. PMID:18643515

Konicek, A R; Grierson, D S; Gilbert, P U P A; Sawyer, W G; Sumant, A V; Carpick, R W

2008-06-11

36

Morphology and electronic structure in nitrogen-doped ultrananocrystalline diamond  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) thin films consist of 2-5 nm grains of pure sp3-bonded carbon and approx0.5-nm-wide grain boundaries with a disordered mixture of sp2- and sp3-bonded carbon. UNCD exhibits many interesting materials properties that are a direct consequence of its nanoscale morphology. In this work, we report the changes in morphology induced in UNCD by the addition of nitrogen gas

James Birrell; J. A. Carlisle; O. Auciello; D. M. Gruen; J. M. Gibson

2002-01-01

37

Mechanical stiffness and dissipation in ultrananocrystalline diamond microresonators  

Microsoft Academic Search

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% sp2 content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, ˜1mum thick, exhibit a

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

2009-01-01

38

Macrotexture and growth chemistry in ultrananocrystalline diamond thin films  

Microsoft Academic Search

We have determined the average preferred crystalline orientation of thin ultrananocrystalline diamond (UNCD) films using X-ray diffraction. The grain size and lattice parameters of the films were also calculated. We show how these characteristics change markedly with the gas chemistry used during growth, adding either 0–20% nitrogen or 0–15% hydrogen to the argon-rich, argon and methane microwave plasma used. We

J. E. Gerbi; J. Birrell; M. Sardela; J. A. Carlisle

2005-01-01

39

Surface properties of differently prepared ultrananocrystalline diamond surfaces  

Microsoft Academic Search

Ultrananocrystalline diamond\\/amorphous carbon composite films have been deposited by microwave plasma chemical vapour deposition from 17% CH4\\/N2 mixtures at 600 °C. Thereafter the films were subjected to various treatments (plasma processes, UV\\/O3 exposure) to obtain hydrogen, oxygen, and fluorine terminated surfaces, which then have been characterized with respect to their composition, roughness, wettability, and other properties. Among others, it will be

W. Kulisch; C. Popov; D. Gilliland; G. Ceccone; L. Sirghi; A. Ruiz; F. Rossi

2009-01-01

40

Formation of ultrananocrystalline diamond films with nitrogen addition  

Microsoft Academic Search

Nitrogen-doped ultrananocrystalline diamond (UNCD) films have been prepared by the microwave plasma jet chemical vapor deposition system (MPJCVD) using a gas mixture of Ar-1%CH4-10%H2 and addition of 0.5–7% nitrogen. This growth process by MPJCVD with 10% hydrogen addition that yields UNCD films compared with those UNCD films produced by MPCVD with a high Ar\\/CH4 ratio due to the focused microwave

Chii-Ruey Lin; Wen-Hsiang Liao; Da-Hua Wei; Jer-Shyong Tsai; Chien-Kuo Chang; Wei-Chuan Fang

2011-01-01

41

Electrical properties of ultrananocrystalline diamond\\/amorphous carbon nanocomposite films  

Microsoft Academic Search

The electrical surface properties of ultrananocrystalline diamond\\/amorphous carbon composite films have been investigated by four-point probe I\\/V and Hall measurements, whereas impedance spectroscopy has been used to establish the electrical bulk properties of the films. It turned out that the surface is p-type conductive with a resistivity of 0.14?cm and a sheet carrier concentration of 7.6×1013cm?2. The bulk resistivity is

W. Kulisch; C. Popov; E. Lefterova; S. Bliznakov; J. P. Reithmaier; F. Rossi

2010-01-01

42

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods  

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

43

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

2012-09-25

44

Hard X-ray Zone Plates Using Ultrananocrystalline Diamond Molds  

NASA Astrophysics Data System (ADS)

While hard x-ray zone plates have made great advances recently towards improved resolution, their focusing efficiency requires further development. This problem becomes more important as higher-energy x-rays are used for x-ray microscopy. The current method for fabricating zone plates involves a dielectric mold, which is then electroplated into, but the materials used for this mold are not mechanically stiff enough for the zone plates desired. Ultrananocrystalline diamond (UNCD) is a form of diamond that can be grown as a thin film by chemical vapor deposition and offers many of the physical properties of bulk diamond. Its mechanical stiffness, resistance to radiation damage, dielectric properties, and ability to be etched suggests UNCD as a capable mold material. Reported is progress in the fabrication of hard x-ray zone plates with gold electroformed into a UNCD mold.

Wojcik, M. J.; Joshi, V.; Sumant, A. V.; Divan, R.; Ocola, L. E.; Lu, M.; Mancini, D. C.

2011-09-01

45

Diamond nanowires and the insulator-metal transition in ultrananocrystalline diamond films  

Microsoft Academic Search

Further progress in the development of the remarkable electrochemical, electron field emission, high-temperature diode, and optical properties of n -type ultrananocrystalline diamond films requires a better understanding of electron transport in this material. Of particular interest is the origin of the transition to the metallic regime observed when about 10% by volume of nitrogen has been added to the synthesis

R. Arenal; P. Bruno; D. J. Miller; M. Bleuel; J. Lal; D. M. Gruen

2007-01-01

46

Comparison of the growth and properties of ultrananocrystalline diamond and nanocrystalline diamond  

Microsoft Academic Search

In this paper we compare and contrast the growth and properties of ultrananocrystalline (UNCD) and nanocrystalline (NCD) diamond. These two structures, grown from hydrogen poor and hydrogen rich plasmas, respectively, have markedly different structural properties. We characterise the plasmas used for growth with in situ optical emission spectroscopy and dual wavelength pyrometry. The films are characterised with scanning electron microscopy

O. A. Williams; M. Daenen; J. D'Haen; K. Haenen; J. Maes; V. V. Moshchalkov; M. Nesládek; D. M. Gruen

2006-01-01

47

Strength of ultrananocrystalline diamond controlled by friction of buried interfaces  

NASA Astrophysics Data System (ADS)

Grain boundary (GB) plasticity plays a critical role in deformation of nanocrystalline (NC) materials. However, it has been unclear how strength of these materials depends on GB properties. We use ultrananocrystalline diamond (UNCD) as a model material in which the plastic deformation is mainly located at the GBs and the dislocation processes are not active. We discover that hardness and yield stress have a simple functional dependence on the stress required for GB sliding. Our results on hydrogenated UNCD demonstrate that phenomena from the field of nanoscale friction can be utilized to understand the deformation of NC materials.

Mo, Yifei; Stone, Donald; Szlufarska, Izabela

2011-10-01

48

Humidity-dependent friction mechanism in an ultrananocrystalline diamond film  

NASA Astrophysics Data System (ADS)

Friction behaviour of an ultrananocrystalline diamond film deposited by the microwave plasma-enhanced chemical vapour deposition technique is studied in a controlled humid atmosphere. The value of friction coefficient consistently decreases while increasing the humidity level during the tribology test. This value is 0.13 under 10% relative humidity conditions, which is significantly decreased to 0.004 under 80% relative humidity conditions. Such a reduction in friction coefficient is ascribed to passivation of dangling covalent bonds of carbon atoms, which occurs due to the formation of chemical species of hydroxyl and carboxylic groups such as C-COO, CH3COH and CH2-O bonding states.

Kumar, N.; Ramadoss, Radhika; Kozakov, A. T.; Sankaran, K. J.; Dash, S.; Tyagi, A. K.; Tai, N. H.; Lin, I.-Nan

2013-07-01

49

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

50

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

51

Ultrananocrystalline Diamond\\/Amorhous Carbon Nanocomposite Films For Biotechnological Applications  

Microsoft Academic Search

Ultrananocrystalline diamond\\/amorphous carbon nanocomposite films have been deposited by MWCVD from CH4\\/N2 mixtures and investigated\\u000a in view of their suitability for applications in modern (nano)biotechnology, e.g. as coatings for implants but also as templates\\u000a for the immobilization of biomolecules e.g. for biosensors or DNA chips. First, some surface properties which are important\\u000a for such applications, e.g. the roughness and the

W. Kulisch; C. Popov

52

Uncovering the Physical Basis Connecting Environment and Tribological Performance of Ultrananocrystalline Diamond.  

National Technical Information Service (NTIS)

In the first year of this project, the researchers studied the nano- scale mechanical and tribological properties of ultrananocrystalline diamond (UNCD), which is a thin-film material known to have extremely high strength and excellent tribological proper...

Y. Jeng

2012-01-01

53

Effect of nitrogen on the electronic properties of ultrananocrystalline diamond thin films grown on quartz and diamond substrates  

Microsoft Academic Search

The electronic transport properties of ultrananocrystalline diamond thin films grown from an argon-rich Ar\\/CH4 microwave plasma have been investigated in the temperature range from 300 up to 700K and as a function of nitrogen added to the gas phase (from 0 to 20%). The influence of nitrogen incorporation on the electronic transport properties of the ultrananocrystalline diamond films was examined

P. Achatz; O. A. Williams; P. Bruno; D. M. Gruen; J. A. Garrido; M. Stutzmann

2006-01-01

54

Enhanced electron field emission properties by tuning the microstructure of ultrananocrystalline diamond film  

NASA Astrophysics Data System (ADS)

Synthesis of microcrystalline-ultrananocrystalline composite diamond (MCD-UNCD) films, which exhibit marvelous electron field emission (EFE) properties, was reported. The EFE of MCD-UNCD composite diamond film can be turned on at a low field as 6.5 V/?m and attain large EFE current density about 1.0 mA/cm2 at 30 V/?m applied field, which is better than the EFE behavior of the nondoped planar diamond films ever reported. The MCD-UNCD films were grown by a two-step microwave plasma enhanced chemical vapor deposition (MPECVD) process, including forming an UNCD layer in CH4/Ar plasma that contains no extra H2, followed by growing MCD layer using CH4/H2/Ar plasma that contains large proportion of H2. Microstructure examinations using high resolution transmission electron microscopy shows that the secondary MPECVD process modifies the granular structure of the UNCD layer, instead of forming a large grain diamond layer on top of UNCD films. The MCD-UNCD composite diamond films consist of numerous ultrasmall grains (~5 nm in size), surrounding large grains about hundreds of nanometer in size. Moreover, there exist abundant nanographites in the interfacial region between the grains that were presumed to form interconnected channels for electron transport, resulting in superior EFE properties for MCD-UNCD composite films.

Cheng, Hsiu-Fung; Chiang, Horng-Yi; Horng, Chuang-Chi; Chen, Huang-Chin; Wang, Chuan-Sheng; Lin, I.-Nan

2011-02-01

55

Ultrananocrystalline diamond thin films functionalized with therapeutically active collagen networks.  

PubMed

The fabrication of biologically amenable interfaces in medicine bridges translational technologies with their surrounding biological environment. Functionalized nanomaterials catalyze this coalescence through the creation of biomimetic and active substrates upon which a spectrum of therapeutic elements can be delivered to adherent cells to address biomolecular processes in cancer, inflammation, etc. Here, we demonstrate the robust functionalization of ultrananocrystalline diamond (UNCD) with type I collagen and dexamethasone (Dex), an anti-inflammatory drug, to fabricate a hybrid therapeutically active substrate for localized drug delivery. UNCD oxidation coupled with a pH-mediated collagen adsorption process generated a comprehensive interface between the two materials, and subsequent Dex integration, activity, and elution were confirmed through inflammatory gene expression assays. These studies confer a translational relevance to the biofunctionalized UNCD in its role as an active therapeutic network for potent regulation of cellular activity toward applications in nanomedicine. PMID:19708260

Huang, Houjin; Chen, Mark; Bruno, Paola; Lam, Robert; Robinson, Erik; Gruen, Dieter; Ho, Dean

2009-03-12

56

Morophology and electronic straucture in nitrogen-doped ultrananocrystalline diamond.  

SciTech Connect

Ultrananocrystalline diamond (UNCD) thin films consist of 2-5 nm grains of pure sp{sub 3}-bonded carbon and {approx}0.5-nm-wide grain boundaries with a disordered mixture of sp{sub 2}- and sp{sub 3}-bonded carbon. UNCD exhibits many interesting materials properties that are a direct consequence of its nanoscale morphology. In this work, we report the changes in morphology induced in UNCD by the addition of nitrogen gas to the Ar/CH{sub 4} microwave plasma, as studied using high-resolution transmission electron microscopy and nanoprobe-based electron energy-loss spectroscopy. Both the grain size and grain-boundary widths increase with the addition of N{sub 2}, but the overall bonding structure in both regions remains mostly unchanged. These results are used to explain the variation of materials properties of nitrogen-incorporated UNCD films.

Birrell, J.; Carlisle, J. A.; Auciello, O.; Gruen, D. M.; Gibson, J. M.; Materials Science Division

2002-09-16

57

Ultrananocrystalline diamond thin films functionalized with therapeutically active collagen networks.  

SciTech Connect

The fabrication of biologically amenable interfaces in medicine bridges translational technologies with their surrounding biological environment. Functionalized nanomaterials catalyze this coalescence through the creation of biomimetic and active substrates upon which a spectrum of therapeutic elements can be delivered to adherent cells to address biomolecular processes in cancer, inflammation, etc. Here, we demonstrate the robust functionalization of ultrananocrystalline diamond (UNCD) with type I collagen and dexamethasone (Dex), an anti-inflammatory drug, to fabricate a hybrid therapeutically active substrate for localized drug delivery. UNCD oxidation coupled with a pH-mediated collagen adsorption process generated a comprehensive interface between the two materials, and subsequent Dex integration, activity, and elution were confirmed through inflammatory gene expression assays. These studies confer a translational relevance to the biofunctionalized UNCD in its role as an active therapeutic network for potent regulation of cellular activity toward applications in nanomedicine.

Huang, H.; Chen, M.; Bruno, P.; Lam, R.; Robinson, E.; Gruen, D.; Ho, D.; Materials Science Division; Northwestern Univ.

2009-01-01

58

Study of optical and electronic properties of Ultrananocrystalline diamond  

NASA Astrophysics Data System (ADS)

Recently Ultrananocrystalline diamond (UNCD) emerged as an engineered material with excellent mechanical, electrical and optical properties. The unique properties were attributed to densely packed sp3 bonded carbon grain of 3-15 nm and the presence of pi-bonded carbon (sp 2) in ? 1 nm grain boundaries. It is believed that in nanocomposite carbon films sp2 bonded carbon sites controls the electronic and optical properties due to their pi-states close to Fermi level, while sp3 matrix control the mechanical properties. We propose that other than the size of sp2 bonded carbon grain boundaries, the ratio of sp3/sp2 bonded carbon volume fraction has significant effect on the optical and electronic (electron field emission) properties. UNCD films were synthesized in Ar-rich (H-poor) high energy density gas plasmas resulting new growth and nucleation mechanism, which involve insertion of C2 into C-C and C-H bonds rather generally accepted atomic hydrogen abstraction and carbon radical (CH3,CH2) insertion in hydrogen rich gas ambient. The high energy density plasma systems used in UNCD synthesis poses serious up-scaling engineering problems for bigger wafer processing and it would be of both fundamental understanding on growth and up-scalability point of view if UNCD can be grown by low energy density hot filament chemical vapor deposition (HFCVD) system over wide parameter window of Ar gas concentration. Continuous UNCD films were grown in Ar-rich gas atmosphere with relatively high growth rates by providing low power (5-10 W) DC plasma in HFCVD system. A detailed study on the parameter window of UNCD films growth in the new system by varying the volume fraction of CH4/(CH4+H2) ˜ 2.5- 17% and Ar/(Ar+H2) ˜ 80-95% were done. The parameter window for the synthesis of UNCD films was studied as a function of argon, methane and hydrogen concentrations, as well as substrate temperature and DC bias. The Energy Filtered Transmission Electron Microscopy, Electron Energy Loss Spectroscopy, Raman Spectroscopy and X-ray Photoelectron Spectroscopy were employed to study the nanocrystalline and diamond-like nature of the UNCD films. Spectroscopic ellipsometry was employed to study the optical and structural properties of UNCD films deposited by DC plasma-assisted Ar-rich HFCVD. The intrinsic optical properties of UNDC were measured in the 1.45-2.88 eV photon range. The compositional analysis were done by modeling (?, Delta) spectra using Bruggeman effective medium approximation with layer structure (surface roughness/bulk) and each layer composed of different volume fractions of sp3, sp2 bonded carbon. The Mueller Matrix Spectroscopic Ellipsometry as complementary method to identify the phase purity of UNCD films by measured 16 elements of Mueller matrix was explained. The temporal current stability and the current fluctuations of the field emission current obtained from UNCD films were investigated. The field emission properties were correlated to the films composition (sp2 and sp3 bonded carbon volume fractions) and nanostructure. The results of the compositional analysis obtained from modeling analysis Spectroscopic Ellipsometry [? (E), Delta (E)] data applied to understand the Electron Field Emission behavior.

Uppireddi, Kishore

59

Integration of piezoelectric aluminum nitride and ultrananocrystalline diamond films for implantable biomedical microelectromechanical devices  

NASA Astrophysics Data System (ADS)

The physics for integration of piezoelectric aluminum nitride (AlN) films with underlying insulating ultrananocrystalline diamond (UNCD), and electrically conductive grain boundary nitrogen-incorporated UNCD (N-UNCD) and boron-doped UNCD (B-UNCD) layers, as membranes for microelectromechanical system implantable drug delivery devices, has been investigated. AlN films deposited on platinum layers on as grown UNCD or N-UNCD layer (5-10 nm rms roughness) required thickness of ~400 nm to induce (002) AlN orientation with piezoelectric d33 coefficient ~1.91 pm/V at ~10 V. Chemical mechanical polished B-UNCD films (0.2 nm rms roughness) substrates enabled (002) AlN film 200 nm thick, yielding d33 = 5.3 pm/V.

Zalazar, M.; Gurman, P.; Park, J.; Kim, D.; Hong, S.; Stan, L.; Divan, R.; Czaplewski, D.; Auciello, O.

2013-03-01

60

Ultrananocrystalline diamond, a new nanocarbon enabled by plasma enhanced chemical vapor deposition  

Microsoft Academic Search

Summary form only given. The idea of making use of the highly energetic carbon dimer molecular species, C2, to nucleate and grow diamond was conceived in 1991. Importantly, this approach obviates the presence of atomic hydrogen to perform sequential hydrogen abstraction reactions, a requirement essential for conventional CVD diamond synthesis. The C2 process uniquely results in the synthesis of ultrananocrystalline

D. M. Gruen; P. Bruno

2006-01-01

61

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

62

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

63

Chemical grafting of biphenyl self-assembled monolayers on ultrananocrystalline diamond  

Microsoft Academic Search

We have investigated the formation of self-assembled monolayers (SAMs) of 4'-nitro-1,1-biphenyl-4-diazonium tetrafluoroborate (NBD) onto ultrananocrystalline diamond (UNCD) thin films. In contrast to the common approach to modify diamond and diamond-like substrates by electrografting, the SAM was formed from the saturated solution of NBD in acetonitrile by pure chemical grafting. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV),

Simon Q. Lud; Marin Steenackers; Rainer Jordan; Paola Bruno; Dieter M. Gruen; Peter Feulner; Jose A. Garrido; Martin Stutzmann

2006-01-01

64

Enhanced nucleation, smoothness and conformality of ultrananocrystalline diamond (UNCD) ultrathin films via tungsten interlayers  

Microsoft Academic Search

Extremely smooth (6nm RMS roughness over 4?m2), thin (100nm), and continuous ultrananocrystalline diamond (UNCD) films were synthesized by microwave plasma chemical vapor deposition using a 10nm tungsten (W) interlayer between the silicon substrate and the diamond film. These UNCD films possess a high content of sp3-bonded carbon. The W interlayer significantly increased the initial diamond nucleation density, thereby lowering the

Nevin N. Naguib; Jeffrey W. Elam; James Birrell; Jian Wang; David S. Grierson; Bernd Kabius; Jon M. Hiller; Anirudha V. Sumant; Robert W. Carpick; Orlando Auciello; John A. Carlisle

2006-01-01

65

Improvement on the growth of ultrananocrystalline diamond by using pre-nucleation technique  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films, which possess very smooth surface, were synthesized using CH4\\/Ar plasma. When the nucleation process was carried out under methane and hydrogen (CH4\\/H2) plasma with negative DC bias voltage, no pretreatment on substrate was required prior to the formation of diamond nuclei. The average grain size of BEN induced diamond nuclei is about 20?30 nm, with the

Yen-Chih Lee; Su-Jien Lin; Debabrata Pradhan; I-Nan Lin

2006-01-01

66

Effects of pretreatment processes on improving the formation of ultrananocrystalline diamond  

SciTech Connect

Effects of pretreatment on the nuclei formation of ultrananocrystalline diamond (UNCD) on Si substrates were studied. Either precoating a thin layer of titanium ({approx}400 nm) or ultrasonication pretreatment using diamond and titanium mixed powder (D and T process) enhances the nucleation process on Si substrates markedly, and the UNCD nuclei formed and fully covered the Si substrate, when deposition was processed using the microwave-plasma-enhanced chemical-vapor deposition process for 10 min. In contrast, during the same period, ultrasonication pretreatment using diamond powders (D process) can only form large UNCD clusters, which were scarcely distributed on Si substrates. The analyses using x-ray diffractometer, secondary ion mass spectroscopy, and electron spectroscopy for chemical analysis reveal that the titanium layer reacted with carbon species in the plasma, forming crystalline TiC phase, which facilitates the subsequent formation of UNCD nuclei. The beneficial effect of Ti layer on enhancing the nucleation of UNCD is presumably owing to high solubility and high diffusivity of carbon species in Ti materials, as compared with those of Si materials.

Chen, Li-Ju; Tai, Nyan-Hwa; Lee, Chi-Young; Lin, I-Nan. [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan 300 (China); Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China)

2007-03-15

67

Using an Au interlayer to enhance electron field emission properties of ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

We observe that an Au interlayer markedly enhances the electrical field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films on Si substrates. The EFE properties of UNCD/Au/Si films can be turned on at a lower field and attain a higher current density than in UNCD films grown on Si substrates without an Au interlayer. Transmission electron microscopy reveals that the Au interlayer induces the formation of SiC clusters, preventing the formation of a resistive amorphous carbon layer that nucleates the diamond clusters. This improves the diamond-to-substrate interfacial conductivity. Moreover, there is an abundant nano-graphite phase, which is presumably induced by the coalescence of nano-sized diamond clusters. The percolation of the nano-graphite clusters helps transport electrons, improving the conductivity of the UNCD films. We believe that the simultaneous increase in the conductivity of the UNCD-to-Si interface and the bulk of the UNCD films is the main factor enhancing electrical conductivity and EFE properties of the films.

Chen, Huang-Chin; Jothiramalingam Sankaran, Kamatchi; Lo, Shen-Chuan; Lin, Li-Jiaun; Tai, Nyan-Hwa; Lee, Chi-Young; Lin, I.-Nan

2012-11-01

68

Effect of titanium powder assisted surface pretreatment process on the nucleation enhancement and surface roughness of ultrananocrystalline diamond thin films  

Microsoft Academic Search

A superior, easy and single-step titanium (Ti) powder assisted surface pretreatment process is demonstrated to enhance the diamond nucleation density of ultrananocrystalline diamond (UNCD) films. It is suggested that the Ti fragments attach to silicon (Si) surface form bond with carbon at a faster rate and therefore facilitates the diamond nucleation. The formation of smaller diamond clusters with higher nucleation

Debabrata Pradhan; I. Nan Lin

2009-01-01

69

Covalent immobilization of glucose oxidase on conducting ultrananocrystalline diamond thin films  

Microsoft Academic Search

We demonstrate in this report the covalent immobilization of redox enzymes onto electrically conductive ultrananocrystalline diamond (UNCD) thin films. Glucose oxidase was attached to the UNCD surface via the tethered aminophenyl functional groups which were previously grafted to UNCD surface by electrochemical reduction of aryl diazonium salt. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) observations confirmed the surface

Jian Wang; John A. Carlisle

2006-01-01

70

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

Microsoft Academic Search

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

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

2007-01-01

71

Fracture strength of ultrananocrystalline diamond thin films-identification of Weibull parameters  

Microsoft Academic Search

The fracture strength of ultrananocrystalline diamond (UNCD) has been investigated using tensile testing of freestanding submicron films. Specifically, the fracture strength of UNCD membranes, grown by microwave plasma chemical vapor deposition (MPCVD), was measured using the membrane deflection experiment developed by Espinosa and co-workers. The data show that fracture strength follows a Weibull distribution. Furthermore, we show that the Weibull

H. D. Espinosa; B. Peng; B. C. Prorok; N. Moldovan; O. Auciello; J. A. Carlisle; D. M. Gruen; D. C. Mancini

2003-01-01

72

Synthesis and field emission properties of hybrid structures of ultrananocrystalline diamond and vertically aligned carbon nanofibers  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films with and without nitrogen doping were deposited onto vertically aligned carbon nanofibers (VACNFs). The field emission properties of these hybrid structures were studied. It is found that the UNCD films were deposited on VACNFs with a high degree of conformality using an optimized seeding process. This hybrid structures exhibited greatly improved macroscopic field emission performance compared

X. Xiao; O. Auciello; Hongtao Cui; Douglas H Lowndes; Vladimir I Merkulov; J. Carlisle

2006-01-01

73

Temperature dependence of mechanical stiffness and dissipation in ultrananocrystalline diamond resonators  

Microsoft Academic Search

We have studied the mechanical softening and dissipation of ultrananocrystalline diamond (UNCD) resonators with temperature. Resonant excitation and ring down measurements were conducted under ultra high vacuum (UHV) conditions in a decoupled UHV atomic force microscope (AFM) to determine the Young's Modulus and quality factor (Q) in UNCD cantilever structures. The temperature dependence of Young's modulus revealed the characteristic Wachtman's

Vivekananda Adiga; Anirudha Sumant; Sampath Suresh; Chris Gudeman; Orlando Auciello; John Carlisle; Robert Carpick

2009-01-01

74

Preventing nanoscale wear of atomic force microscopy tips through the use of monolithic ultrananocrystalline diamond probes.  

PubMed

Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) probes that results in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Diamond is potentially an ideal probe material due to its unrivaled hardness and stiffness, its low friction and wear, and its chemical inertness. However, the manufacture of monolithic diamond probes with consistently shaped small-radius tips has not been previously achieved. The first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes with <5-nm grain sizes and smooth tips with radii of 30-40 nm is reported, which are obtained through a combination of microfabrication and hot-filament chemical vapor deposition. Their nanoscale wear resistance under contact-mode scanning conditions is compared with that of conventional silicon nitride (SiN(x)) probes of similar geometry at two different relative humidity levels (approximately 15 and approximately 70%). While SiN(x) probes exhibit significant wear that further increases with humidity, UNCD probes show little measurable wear. The only significant degradation of the UNCD probes observed in one case is associated with removal of the initial seed layer of the UNCD film. The results show the potential of a new material for AFM probes and demonstrate a systematic approach to studying wear at the nanoscale. PMID:20486220

Liu, J; Grierson, D S; Moldovan, N; Notbohm, J; Li, S; Jaroenapibal, P; O'Connor, S D; Sumant, A V; Neelakantan, N; Carlisle, J A; Turner, K T; Carpick, R W

2010-05-21

75

Surface Functionalization of Plasma Treated Ultrananocrystalline Diamond/Amorphous Carbon Composite Films  

NASA Astrophysics Data System (ADS)

Diamond possesses a number of outstanding properties which make it a perspective material as platform for preparation of biosensors. The diamond surface needs to be activated before the chemical attachment of crosslinkers with which biomolecules can interact. In the current work we have investigated the modification of ultrananocrystalline diamond/amorphous carbon (UNCD/a-C) films by oxygen and ammonia plasmas. Afterwards the layers were functionalized in a further step to obtain thiol-active maleimide groups on the surface. We studied the possibility for direct binding of maleimide to terminal OH-groups on the UNCD surface and for silanization with 3-aminopropyltriethoxysilane (APTES) to obtain NH2-groups for the following attachment of sulfosuccinimidyl 4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SSMCC). The thiol-bearing fluorescein-related dye 5-((2-(and-3)-S-(acetylmercapto) succinoyl) amino) fluorescein (SAMSA) was immobilized as an model biomolecule to evaluate the achieved thiol-activity by fluorescence microscopy. The results of the above mentioned surface modification and functionalization steps were investigated by Auger electron spectroscopy (AES) and contact angle measurements.

Koch, Hermann; Popov, Cyril; Kulisch, Wilhelm; Spassov, G.; Reithmaier, Johann Peter

76

Ion Beam Irradiation Studies Of Ultrananocrystalline Diamond (UNCD)  

NASA Astrophysics Data System (ADS)

Investigations into the effects of high-energy ion bombardment of ultrananocrystalline diamond (UNCD) thin films was performed using 3 and 6 MeV protons and 24 MeV F4+, with the fluence of 2.1×1017 ions/cm2, 2.9×1017 ions/cm2, and 6.7×1015 ions/cm2 respectively. Objective of the research is to investigate the effect of structural damage on the physical properties of the material and compare it with the structure of unirradiated and N doped UNCD. Pre- and post-irradiated samples were analyzed by ion beam analysis (IBA) measurements, Raman spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). IBA measurements including Rutherford backscattering spectrometry (RBS), non-Rutherford backscattering spectrometry (NRBS) and elastic recoil detection analysis (ERDA) were used to determine elemental concentration of pre- and post-irradiated samples. Visible Raman spectra corresponding to samples irradiated at 3 and 6 MeV protons did not show much variation. For 24 MeV F4+ irradiated sample, significant changes were observed, particularly the loss of a shoulder at 1179 cm-1 and sharpening of the G peak at around 1532 cm-1, indicating possible significant changes at the grain boundary and increase in sp2 phase. AFM measurements show a reduction in RMS roughness after bombardment possibly due to the graphitization of the UNCD surface. The results of IBA measurements did not show any change in the elemental concentration or interface region between film and substrate.

Kayani, A.; Garratt, E.; Alfaify, S.; Dissanayake, A.; Tecos, G.; Mancini, D. C.; Syed, M.

2011-06-01

77

Thermal transport and grain boundary conductance in ultrananocrystalline diamond thin films  

Microsoft Academic Search

Although diamond has the highest known room temperature thermal conductivity, k~2200 W\\/m K, highly sp3 amorphous carbon films have k<15 W\\/m K. We carry out an integrated experimental and simulation study of thermal transport in ultrananocrystalline diamond (UNCD) films. The experiments show that UNCD films with a grain size of 3-5 nm have thermal conductivities as high as k=12 W\\/m

Maki A. Angadi; Taku Watanabe; Arun Bodapati; Xingcheng Xiao; Orlando Auciello; John A. Carlisle; Jeffrey A. Eastman; Pawel Keblinski; Patrick K. Schelling; Simon R. Phillpot

2006-01-01

78

Bulk and surface-enhanced Raman spectroscopy of nitrogen-doped ultrananocrystalline diamond films  

Microsoft Academic Search

Ultrananocrystalline diamond films (UNCD) grown in an Ar-rich microwave plasma with nitrogen gas added in amounts of 0-25% were studied by Raman spectroscopy using 514.5 and 413.1 nm laser excitation. Besides the Raman spectra of diamond, the first and second order Raman scattering of disordered graphite and polyacetylene were detected and analyzed for samples with different nitrogen content. With surface

I. I. Vlasov; V. G. Ralchenko; E. Goovaerts; A. V. Saveliev; M. V. Kanzyuba

2006-01-01

79

Tight-binding molecular-dynamics simulation of impurities in ultrananocrystalline diamond grain boundaries  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films grown from hydrogen-poor plasmas have grain sizes of 3-10 nm, resulting in a large number of grain boundaries. We report on density-functional-based tight-binding molecular-dynamics calculations of high-energy high-angle twist (100) grain boundaries in diamond as a model for the UNCD grain boundaries. About one-half of the carbons in the grain boundary are threefold coordinated and are

Peter Zapol; Michael Sternberg; Larry A. Curtiss; Thomas Frauenheim; Dieter M. Gruen

2002-01-01

80

Immobilization of horseradish peroxidase via an amino silane on oxidized ultrananocrystalline diamond  

Microsoft Academic Search

We discuss the complete functionalization of nitrogen-doped ultrananocrystalline diamond (UNCD) films, starting from an oxidized surface. First, the presence of hydroxyl groups on oxidized nanocrystalline diamond (NCD) was confirmed by fluorescence microscopy. Next, the grafting of a linker molecule such as 3-aminopropylmethyldiethoxysilane on oxidized NCD was confirmed by fluorescence microscopy and X-ray photoelectron spectroscopy (XPS). Then the horseradish peroxidase (HRP)

Jorge Hernando; Tahmineh Pourrostami; Jose A. Garrido; Oliver A. Williams; Dieter M. Gruen; Alexander Kromka; Doris Steinmüller; Martin Stutzmann

2007-01-01

81

Electron paramagnetic resonance study of hydrogen-incorporated ultrananocrystalline diamond thin films  

Microsoft Academic Search

Hydrogen-incorporated ultrananocrystalline diamond (UNCD) thin films have been deposited in microwave plasma enhanced chemical vapor deposition (MPECVD) system with various hydrogen concentrations in the Ar\\/CH4 gas mixture, and characterized by several techniques including electron paramagnetic resonance (EPR), Raman spectroscopy, scanning electron microscope (SEM), and dc conductivity measurements. The EPR spectrum of diamond film was composed of two Lorentzian lines with

Chao Liu; Xingcheng Xiao; Hsien-Hau Wang; Orlando Auciello; John A. Carlisle

2007-01-01

82

The mechanical properties of single-crystal and ultrananocrystalline diamond: A theoretical study  

Microsoft Academic Search

We examine the mechanical properties of single-crystal and ultrananocrystalline diamond (UNCD) by simulating their fracture using semiempirical quantum mechanics and density functional theory. Our results predict a failure strain of 0.13 and a fracture stress of 100GPa for UNCD, which are 37% and 43%, respectively, that of single-crystal diamond. The Young’s modulus of UNCD is E=1.05 TPa which is only

Jeffrey T. Paci; Ted Belytschko; George C. Schatz

2005-01-01

83

Diamond nanowires and the insulator-metal transition in ultrananocrystalline diamond films.  

SciTech Connect

Further progress in the development of the remarkable electrochemical, electron field emission, high-temperature diode, and optical properties of n-type ultrananocrystalline diamond films requires a better understanding of electron transport in this material. Of particular interest is the origin of the transition to the metallic regime observed when about 10% by volume of nitrogen has been added to the synthesis gas. Here, we present data showing that the transition to the metallic state is due to the formation of partially oriented diamond nanowires surrounded by an sp{sup 2}-bonded carbon sheath. These have been characterized by scanning electron microscopy, transmission electron microscopy techniques (high-resolution mode, selected area electron diffraction, and electron-energy-loss spectroscopy), Raman spectroscopy, and small-angle neutron scattering. The nanowires are 80-100 nm in length and consist of {approx}5 nm wide and 6-10 nm long segments of diamond crystallites exhibiting atomically sharp interfaces. Each nanowire is enveloped in a sheath of sp{sup 2}-bonded carbon that provides the conductive path for electrons. Raman spectroscopy on the films coupled with a consideration of plasma chemical and physical processes reveals that the sheath is likely composed of a nanocarbon material resembling in some respects a polymer-like mixture of polyacetylene and polynitrile. The complex interactions governing the simultaneous growth of the diamond core and the sp{sup 2} sheath responsible for electrical conductivity are discussed as are attempts at a better theoretical understanding of the transport mechanism.

Arenal, R.; Bruno, P.; Miller, D. J.; Bleuel, M.; Lai, J.; Gruen, D. M.

2007-05-01

84

Multiwavelength Raman spectroscopy of diamond nanowires present in n-type ultrananocrystalline films.  

SciTech Connect

Multiwavelength Raman spectroscopy is employed to investigate ultrananocrystalline diamond films deposited by the plasma enhanced chemical vapor deposition technique. Recently, we have shown that the addition of nitrogen in the gas source during synthesis induce the formation of diamond n-type films, exhibiting the highest electrical conductivity at ambient temperature. This point is related with the formation of elongated diamond nanostructures and the presence of sp{sup 2}-bonded carbon in these films. The Raman results presented here confirm these aspects and provide a better and deeper understanding of the nature of these films and their related optical and electronic properties.

Arenal , R.; Montagnac, G.; Bruno, P.; Gruen, D. M.; Materials Science Division; ONERA-CNRS; Ecole Normale Superieure de Lyon

2007-12-01

85

Optical and mechanical characterization of ultrananocrystalline diamond films prepared in dual frequency discharges  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films were deposited directly on polished silicon substrates in microwave discharge (2.45GHz) combined with rf capacitive plasma (13.56MHz) ignited at the substrate electrode. The rf discharge induced a dc self-bias accelerating ions towards the growing film during the whole deposition process. The applied microwave and rf powers were 900W and 35W, respectively. The gas mixture contained 9.4%

Monika Karásková; Lenka Zají?ková; Vilma Buršíková; Daniel Franta; David Ne?as; Olga Bláhová; Ji?í Šperka

2010-01-01

86

Synthesis and characterization of highly-conducting nitrogen-doped ultrananocrystalline diamond films  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films with up to 0.2% total nitrogen content were synthesized by a microwave plasma-enhanced chemical-vapor-deposition method using a CH4(1%)\\/Ar gas mixture and 1%-20% nitrogen gas added. The electrical conductivity of the nitrogen-doped UNCD films increases by five orders of magnitude (up to 143 Omega-1 cm-1) with increasing nitrogen content. Conductivity and Hall measurements made as a function

S. Bhattacharyya; O. Auciello; J. Birrell; J. A. Carlisle; L. A. Curtiss; A. N. Goyette; D. M. Gruen; A. R. Krauss; J. Schlueter; A. Sumant; P. Zapol

2001-01-01

87

Optical properties of ultrananocrystalline diamond\\/amorphous carbon composite films prepared by pulsed laser deposition  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD)\\/amorphous carbon (a-C) composite thin films were grown in ambient hydrogen by pulsed laser deposition using a graphite target, and their optical properties were determined by optical absorption spectroscopy and Raman scattering spectroscopy. Three optical bandgaps exist. Two bandgaps are indirect and their values were estimated to be 1.0 eV and 5.4 eV; these bandgaps correspond to the a-C surrounding

Akira Nagano; Tsuyoshi Yoshitake; Takeshi Hara; Kunihito Nagayama

2008-01-01

88

Growth and electron field emission properties of ultrananocrystalline diamond on silicon nanostructures  

Microsoft Academic Search

The electron field emission (EFE) properties of Si nanostructures (SiNS), such as Si nanorods (SiNR) and Si nanowire (SiNW) bundles were investigated. Additionally, ultrananocrystalline diamond (UNCD) growth on SiNS was carried out to improve the EFE properties of SiNS via forming a combined UNCD\\/SiNS structure. The EFE properties of SiNS were improved after the deposition of UNCD at specific growth

P. T. Joseph; N. H. Tai; Y. F. Cheng; C. Y. Lee; H. F. Cheng; I. N. Lin

2009-01-01

89

Electrochemical impedance spectroscopy of oxidized and hydrogen-terminated nitrogen-induced conductive ultrananocrystalline diamond  

Microsoft Academic Search

We have studied the electrochemical impedance spectroscopy of conductive ultrananocrystalline diamond (UNCD) modified by either oxidation or hydrogenation surface treatments. The impedance was measured in the frequency range from 0.1Hz to 40kHz at different DC voltages and the results fitted to an equivalent electrical circuit. Despite the complexity of the conductive UNCD surface, composed of sp3-bonded grains and grain boundaries

Jorge Hernando; Simon Q. Lud; Paola Bruno; Dieter M. Gruen; Martin Stutzmann; Jose A. Garrido

2009-01-01

90

Synthesis of thick, uniform, smooth ultrananocrystalline diamond films by microwave plasma-assisted chemical vapor deposition  

Microsoft Academic Search

The deposition of uniform, low-stress, thick and thin films of ultrananocrystalline diamond (UNCD) is investigated. The process methods and apparatus that enable the uniform and smooth deposition of both thin and thick (>50 ?m) UNCD across 3 in. diameters are described. UNCD films are synthesized by microwave plasma-assisted CVD using Ar\\/H2\\/CH4 input gas mixtures over a wide pressure range (60–240

W. S. Huang; D. T. Tran; J. Asmussen; T. A. Grotjohn; D. Reinhard

2006-01-01

91

Wettability and protein adsorption on ultrananocrystalline diamond\\/amorphous carbon composite films  

Microsoft Academic Search

Ultrananocrystalline diamond\\/amorphous carbon (UNCD\\/a-C) composite films have been prepared by microwave plasma chemical vapour deposition (MWCVD) from 17% CH4\\/N2 mixtures and modified with O2 and CHF3 plasmas, which changed the surface termination from hydrogen to oxygen and fluorine, respectively. X-ray photoelectron spectroscopy (XPS) showed that successful oxidation and fluorination of the UNCD surface has been achieved with surface O or

C. Popov; H. Vasilchina; W. Kulisch; F. Danneil; M. Stüber; S. Ulrich; A. Welle; J. P. Reithmaier

2009-01-01

92

Defects localization and nature in bulk and thin film ultrananocrystalline diamond.  

SciTech Connect

We report about the electron paramagnetic resonance and nuclear magnetic resonance signals in bulk and thin film-type ultrananocrystalline diamond with and without nitrogen. The localization and nature of defects for powder and compact film samples were analyzed. From the analysis of spin-lattice and spin-spin relaxation times, we have found that spin states sit in sp{sup 2} enriched region belonging to the grain boundaries.

Shames, A. I.; Panich, A. M.; Porro, S.; Rovere, M.; Musso, S.; Tagliaferro, A.; Baidakova, M. V.; Osipov, V. Yu.; Vul, A. Ya.; Enoki, T.; Takahashi, M.; Osawa, E.; Williams, O. A.; Bruno, P.; Gruen, D. M.; Ben-Gurion Univ. of the Negev; Politecnico; Ioffe Physico-Technical Inst.; Tokyo Inst. of Tech.; NanoCarbon Research Inst.

2007-01-01

93

Influence of the nucleation density on the structure and mechanical properties of ultrananocrystalline diamond films  

Microsoft Academic Search

The influence of the nucleation density on the development of the morphology of ultrananocrystalline diamond\\/amorphous carbon (UNCD\\/a-C) composite films and their mechanical properties has been investigated by variation of the substrate pre-treatment used to enhance the nucleation. The films have been prepared by microwave plasma chemical vapour deposition from 17% CH4\\/N2 mixtures on silicon substrates. Their morphology and topography have

C. Popov; G. Favaro; W. Kulisch; J. P. Reithmaier

2009-01-01

94

SCIENCE AND TECHNOLOGY OF ULTRANANOCRYSTALLINE DIAMOND FILMS FOR MULTIFUNCTIONAL MEMS\\/NEMS DEVICES  

Microsoft Academic Search

The objectives of this project are to investigate microstructure-mechanical-electronic transport property relationships of a new multifunctional material designated as ultrananocrystalline diamond (UNCD), and to utilize this material in microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS). Through interdisciplinary research and educational efforts of the team members from Northwestern University (NU), University of Illinois at Chicago (UIC) and University of Missouri-Columbia (UMC),

Z. Chen; H. Espinosa; M. Hersam; O. Auciello; T. Belytschko; G. Schatz; J. A. Carlisle

2004-01-01

95

Electron paramagnetic resonance study of hydrogen-incorporated ultrananocrystalline diamond thin films.  

SciTech Connect

Hydrogen-incorporated ultrananocrystalline diamond (UNCD) thin films have been deposited in microwave plasma enhanced chemical vapor deposition (MPECVD) system with various hydrogen concentrations in the Ar/CH{sub 4} gas mixture, and characterized by several techniques including electron paramagnetic resonance (EPR), Raman spectroscopy, scanning electron microscope (SEM), and dc conductivity measurements. The EPR spectrum of diamond film was composed of two Lorentzian lines with different g factors. When hydrogen concentration in the plasma increased during diamond growth, the spin density of the narrow line decreased, whereas the spin density of the broad signal remained roughly constant. We propose that the two EPR components can be attributed to two different phases in the diamond film, i.e., the narrow line is originated from the highly defective grain boundary region and the broad line is related to the defects in the diamond grains.

Liu, C.; Xiao, X.; Wang, H.-H.; Auciello, O.; Carlisle, J. A.

2007-01-01

96

Piezoelectric\\/ultrananocrystalline diamond heterostructures for high-performance multifunctional micro\\/nanoelectromechanical systems  

Microsoft Academic Search

Most current micro\\/nanoelectromechanical systems (MEMS\\/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical\\/tribological properties, compromising applications to some devices. Diamond films with superior mechanical\\/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD®) in film form with 2-5 nm grains exhibits excellent properties for high-performance MEMS\\/NEMS devices. Concurrently, piezoelectric Pb(ZrxTi1-x)O3 (PZT) films provide high sensitivity\\/low electrical noise

S. Srinivasan; J. Hiller; B. Kabius; O. Auciello

2007-01-01

97

Quantum Chemical Studies of Growth Mechanisms of Ultrananocrystalline Diamond  

Microsoft Academic Search

Computational studies of growth mechanisms on diamond surfaces based on C2precursor have been reviewed. The investigations have postulated reaction mechanisms with diamond growth occurring by insertion of C2into the C-H bonds of the hydrogen-terminated diamond surface or into ?- bonded carbon dimers on dehydrogenated diamond surfaces. Reaction barriers for both growth and renucleation at (011) and (100) diamond surfaces had

L. A. Curtiss; P. Zapoll; M. Sternberg; P. C. Redfernm; D. A. Horner; D. M. Gruen

2004-01-01

98

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

2012-07-31

99

Origin of Ultralow Friction and Wear in Ultrananocrystalline Diamond.  

National Technical Information Service (NTIS)

The impressively low friction and wear of diamond in humid environments is debated to originate from either the stability of the passivated diamond surface or sliding-induced graphitization/rehybridization of carbon. We find ultralow friction and wear for...

A. R. Konicek A. V. Sumant D. S. Grierson P. U. Gilbert W. G. Sawyer

2008-01-01

100

Novel method of growing ultrananocrystalline diamond tips and their field emission property study.  

PubMed

Different forms of diamond have been shown to have qualities as field emission sources. As a consequence, much effort has been focused on both the synthesis of diamond nanostructures to increase the field enhancement factor and understanding the emission mechanism in these nominally insulating materials. In our recent study, we have grown ultrananocrystalline diamond (UNCD) coated nanocrystalline diamond (NCD) tips on NCD films for field emitters. The films were characterized using field emission scanning electron microscopy and Raman spectroscopy to identify the quality of the films. The fabricated different sizes of pyramid tips and their field emission properties are reported. It has been observed that with increase in tip size, the turn on voltage also increases. PMID:19049202

Joseph, P T; Chen, Li-Ju; Tai, Nyan-Hwa; Palnitkar, Umesh; Cheng, Hsiu-Fung; Lin, I-Nan

2008-08-01

101

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

102

Novel ultrananocrystalline diamond probes for high-resolution low-wear nanolithographic techniques.  

PubMed

A hard, low-wear probe for contact-mode writing techniques, such as dip-pen nanolithography (DPN), was fabricated using ultrananocrystalline diamond (UNCD). Molding within anisotropically etched and oxidized pyramidal pits in silicon was used to obtain diamond tips with radii down to 30 nm through growth of UNCD films followed by selective etching of the silicon template substrate. The probes were monolithically integrated with diamond cantilevers and subsequently integrated into a chip body obtained by metal electroforming. The probes were characterized in terms of their mechanical properties, wear, and atomic force microscopy imaging capabilities. The developed probes performed exceptionally well in DPN molecular writing/imaging mode. Furthermore, the integration of UNCD films with appropriate substrates and the use of directed microfabrication techniques are particularly suitable for fabrication of one- and two-dimensional arrays of probes that can be used for massive parallel fabrication of nanostructures by the DPN method. PMID:17193541

Kim, Keun-Ho; Moldovan, Nicolaie; Ke, Changhong; Espinosa, Horacio D; Xiao, Xingcheng; Carlisle, John A; Auciello, Orlando

2005-08-01

103

Interpretation of the Raman spectra of ultrananocrystalline diamond  

Microsoft Academic Search

It has long been known that by slightly altering the deposition conditions for diamond in plasma-enhanced chemical vapor deposition (PECVD), a transition from a microcrystalline to a nanocrystalline diamond morphology can be affected. The method of this transition, however, is not clear. This work investigates that transition by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Raman spectroscopy.

James Birrell; J. E. Gerbi; O. Auciello; J. M. Gibson; J. Johnson; J. A. Carlisle

2005-01-01

104

Synthesis and Field Emission Properties of Hybrid Structures of Ultrananocrystalline Diamond and Vertically Aligned Carbon Nanofibers  

SciTech Connect

Ultrananocrystalline diamond (UNCD) films with and without nitrogen doping were deposited onto vertically aligned carbon nanofibers (VACNFs). The field emission properties of these hybrid structures were studied. It is found that the UNCD films were deposited on VACNFs with a high degree of conformality using an optimized seeding process. This hybrid structures exhibited greatly improved macroscopic field emission performance compared with uncoated VACNFs. Further enhancement was observed for nitrogen-doped UNCD on VACNFs, with low threshold field emission (2.5 V/{micro}m) and low work functions for the field emission. The stability of the emission was also improved as compared to the uncoated VACNFs.

Xiao, X. [Argonne National Laboratory (ANL); Auciello, O. [Argonne National Laboratory (ANL); Cui, Hongtao [ORNL; Lowndes, Douglas H [ORNL; Merkulov, Vladimir I [ORNL; Carlisle, J. [Argonne National Laboratory (ANL)

2006-01-01

105

Temperature dependence of reversible switch-memory in electron field emission from ultrananocrystalline diamond  

NASA Astrophysics Data System (ADS)

Temperature dependence of reversible hysteretic switching in electron field emission from surface transfer doped ultrananocrystalline diamond (UNCD) thin films is reported. Sharp jumps (up to 3 orders of magnitude) of the current, at specific ramp up and down extracting electric field values, are found. The memory-window, i.e., hysteresis widths, of the emitted current is controllable by heating (50 °C to 250 °C). The temperature dependence of the hysteresis is explained as being due to conductivity properties of the transfer doped UNCD film namely, by the electrons supply to emission sites. These results may find application in memory-switch devices with tunable properties.

Tordjman, M.; Bolker, A.; Saguy, C.; Kalish, R.

2012-10-01

106

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

107

Characterization of low-temperature ultrananocrystalline diamond RF MEMS resonators  

Microsoft Academic Search

For the first time working MEMS resonators have been produced using low-temperature deposited (550degC) ultrananocrystallinetrade diamond (UNCDtrade) films. Using a lumped-element model to fit experimental data, UNCD materials properties such as a Young's modulus of 710 GPa and an acoustic velocity of 14,243 m\\/s have been deduced. This is the highest acoustic velocity measured to date for a diamond MEMS

Sergio P. Pacheco; Peter Zurcher; S. R. Young; D. Weston; W. J. Dauksher; O. Auciello; J. A. Carlisle; N. Kane; J. P. Birrell

2005-01-01

108

An investigation of grain size and nitrogen-doping effects on the mechanical properties of ultrananocrystalline diamond films  

Microsoft Academic Search

Due to the lack of thorough understanding of the ultrananocrystalline diamond (UNCD) growth mechanism, a simple procedure is proposed to form a polycrystalline UNCD block with an artificial grain boundary (GB). The mechanical responses of the resulting UNCD films with various grain sizes are investigated by applying displacement-controlled tensile loading in the molecular dynamics simulations. By randomly adding different numbers

Luming Shen; Zhen Chen

2007-01-01

109

A study of mechanical properties of pure and nitrogen-doped ultrananocrystalline diamond films under various loading conditions  

Microsoft Academic Search

To better understand the mechanical responses of ultrananocrystalline diamond (UNCD) under various loading conditions, a numerical study is performed to investigate the size, loading rate and temperature effects on the material properties of pure and nitrogen-doped UNCD films. Since the UNCD growth mechanism is not completely understood yet, a simple procedure by combining kinetic Monte Carlo and molecular dynamics (MD)

Luming Shen; Zhen Chen

2009-01-01

110

Electrical conduction in undoped ultrananocrystalline diamond thin films and its dependence on chemical composition and crystalline structure  

Microsoft Academic Search

The electrical conduction behavior of undoped ultrananocrystalline diamond (UNCD) and its dependence on deposition temperature and chemical structure are presented. UNCD films were grown using a microwave plasma-enhanced chemical vapor deposition technique at deposition temperatures of 400 °C and 800 °C. The chemical structure of the UNCD films is characterized with several tools including: Elastic recoil detection analysis, Fourier transform

Eric J. Correa; Yan Wu; Jian-Guo Wen; Ramesh Chandrasekharan; Mark A. Shannon

2007-01-01

111

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

Microsoft Academic Search

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

D. B. Seley; D. A. Dissing; R. Divan; C. S. Miller; O. Auciello; E. A. Terrell; T. S. Shogren; D. Fahrner; J. P. Hamilton; M. P. Zach; V. Sumant

2011-01-01

112

Effect of gases on the field emission properties of ultrananocrystalline diamond-coated silicon field emitter arrays  

Microsoft Academic Search

We performed studies of electron emission from ultrananocrystalline diamond (UNCD)-coated, ungated silicon field emitters as a function of in situ exposure to various gases during current versus voltage and current versus time measurements. The emitter arrays were fabricated by a subtractive tip fabrication process and coated with UNCD films using microwave plasma chemical vapor deposition with a CH4\\/Ar plasma chemistry.

M. Hajra; C. E. Hunt; M. Ding; O. Auciello; J. Carlisle; D. M. Gruen

2003-01-01

113

Status review of the science and technology of ultrananocrystalline diamond (UNCD™) films and application to multifunctional devices  

Microsoft Academic Search

This review focuses on a status report on the science and technology of ultrananocrystalline diamond (UNCD) films developed and patented at Argonne National Laboratory. The UNCD material has been developed in thin film form and exhibit multifunctionalities applicable to a broad range of macro to nanoscale multifunctional devices. UNCD thin films are grown by microwave plasma chemical vapor deposition (MPCVD)

Orlando Auciello; Anirudha V. Sumant

2010-01-01

114

Loading History Effect on Size-Dependent Shear Strength of Pure and Nitrogen-Doped Ultrananocrystalline Diamond  

Microsoft Academic Search

A numerical study is performed to investigate the effect of loading history on the size-dependent material properties of pure and nitrogen-doped ultrananocrystalline diamond (UNCD) specimens under different shear loading paths. A simple procedure with combined kinetic Monte Carlo and molecular dynamics methods is adopted to form a polycrystalline UNCD with an artificial grain boundary (GB). By randomly adding different numbers

Luming Shen; Zhen Chen

2009-01-01

115

Direct observation of enhanced emission sites in nitrogen implanted hybrid structured ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

A hybrid-structured ultrananocrystalline diamond (h-UNCD) film, synthesized on Si-substrates by a two-step microwave plasma enhanced chemical vapour deposition (MPECVD) process, contains duplex structure with large diamond aggregates evenly dispersed in a matrix of ultra-small grains (~5 nm). The two-step plasma synthesized h-UNCD films exhibit superior electron field emission (EFE) properties than the one-step MPECVD deposited UNCD films. Nitrogen-ion implantation/post-annealing processes further improve the EFE properties of these films. Current imaging tunnelling spectroscopy in scanning tunnelling spectroscopy mode directly shows increased density of emission sites in N implanted/post-annealed h-UNCD films than as-prepared one. X-ray photoelectron spectroscopy measurements show increased sp2 phase content and C-N bonding fraction in N ion implanted/post-annealed films. Transmission electron microscopic analysis reveals that the N implantation/post-annealing processes induce the formation of defects in the diamond grains, which decreases the band gap and increases the density of states within the band gap of diamond. Moreover, the formation of nanographitic phase surrounding the small diamond grains enhanced the conductivity at the diamond grain boundaries. Both of the phenomena enhance the EFE properties.

Panda, Kalpataru; Chen, Huang-Chin; Sundaravel, B.; Panigrahi, B. K.; Lin, I.-Nan

2013-02-01

116

Origin of a needle-like granular structure for ultrananocrystalline diamond films grown in a N2\\/CH4 plasma  

Microsoft Academic Search

Microstructural evolution as a function of substrate temperature (TS) for conducting ultrananocrystalline diamond (UNCD) films is systematically studied. Variation of the sp2 graphitic and sp3 diamond content with TS in the films is analysed from the Raman and near-edge x-ray absorption fine structure spectra. Morphological and microstructural studies confirm that at TS = 700 °C well-defined acicular structures evolve. These

K J Sankaran; J Kurian; H C Chen; C L Dong; C Y Lee; N H Tai; I N Lin

2012-01-01

117

On the enhancement of field emission performance of ultrananocrystalline diamond coated nanoemitters  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD) nanoemitters were synthesized by a microwave plasma enhanced chemical vapor deposition process using silicon nanowires (SiNWs) as the template. Preseeding markedly enhances the nucleation of diamond on the SiNW templates, resulting in UNCD grains of smaller size and uniform distribution, which leads to significantly improved electron field emission (EFE) properties. The EFE for UNCD nanoemitters can be turned on at (E0)UNCD-NE=4.4 V/?m, achieving large EFE current density, (Je)UNCD-NE=13.9 mA/cm2 at an applied field of 12 V/?m, which is comparable with that of carbon nanotubes, but with much better processing reliability.

Tzeng, Yu-Fen; Lee, Yen-Chih; Lee, Chi-Young; Lin, I.-Nan; Chiu, Hsin-Tien

2007-08-01

118

Synthesis and characterization of highly-conducting nitrogen-doped ultrananocrystalline diamond films  

SciTech Connect

Ultrananocrystalline diamond (UNCD) films with up to 0.2% total nitrogen content were synthesized by a microwave plasma-enhanced chemical-vapor-deposition method using a CH{sub 4}(1%)/Ar gas mixture and 1%--20% nitrogen gas added. The electrical conductivity of the nitrogen-doped UNCD films increases by five orders of magnitude (up to 143 {Omega}-1 cm-1) with increasing nitrogen content. Conductivity and Hall measurements made as a function of film temperature down to 4.2 K indicate that these films have the highest n-type conductivity and carrier concentration demonstrated for phase-pure diamond thin films. Grain-boundary conduction is proposed to explain the remarkable transport properties of these films.

Bhattacharyya, S.; Auciello, O.; Birrell, J.; Carlisle, J. A.; Curtiss, L. A.; Goyette, A. N.; Gruen, D. M.; Krauss, A. R.; Schlueter, J.; Sumant, A. (and others)

2001-09-03

119

On the enhancement of field emission performance of ultrananocrystalline diamond coated nanoemitters  

SciTech Connect

Ultrananocrystalline diamond (UNCD) nanoemitters were synthesized by a microwave plasma enhanced chemical vapor deposition process using silicon nanowires (SiNWs) as the template. Preseeding markedly enhances the nucleation of diamond on the SiNW templates, resulting in UNCD grains of smaller size and uniform distribution, which leads to significantly improved electron field emission (EFE) properties. The EFE for UNCD nanoemitters can be turned on at (E{sub 0}){sub UNCD-NE}=4.4 V/{mu}m, achieving large EFE current density, (J{sub e}){sub UNCD-NE}=13.9 mA/cm{sup 2} at an applied field of 12 V/{mu}m, which is comparable with that of carbon nanotubes, but with much better processing reliability.

Tzeng, Y.-F.; Lee, Y.-C.; Lee, C.-Y.; Lin, I.-N.; Chiu, H.-T. [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30043, Taiwan (China); Center of Nanotechnology, Materials Science, and Microsystem, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30043, Taiwan (China); Department of Physics, Tamkang University, 151 Ying-Chuan Rd., Tamsui 251, Taiwan (China); Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30050, Taiwan (China)

2007-08-06

120

Piezoelectric/ultrananocrystalline diamond heterostructures for a new generation of multifunctional micro/nanoelectromechanical systems.  

SciTech Connect

Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical/tribological properties, compromising applications to some devices. Diamond films with superior mechanical/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD{reg_sign}) 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 letter describes the bases of such integration and demonstration of low voltage piezoactuated hybrid PZT/UNCD cantilevers.

Srinivasan, S.; Hiller, J.; Kabius, B.; Auciello, O.

2007-01-01

121

Monolithic n-type conductivity on low temperature grown freestanding ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

We report monolithic n-type conductivity on low-temperature (<570 °C) grown ultrananocrystalline diamond (UNCD) films by Li-diffusion (about 255 nm) from LiNbO3 substrates. Low resistivity of 1.2 ? cm with carrier concentration of -2×1020 cm-3 is obtained on freestanding UNCD films. The films bonded to Cu-tape show very low turn-on field of 4.2 V/?m with emission current density of above 0.3 mA/cm2 at a low applied filed of 10 V/?m. The n-type conductivity of low-temperature Li-diffused UNCD films overwhelms that of the high-temperature (>=800 °C) nitrogen doped ones and will make a significant impact to diamond-based electronics.

Joseph, P. T.; Tai, N. H.; Lin, I. N.

2010-07-01

122

Fabrication of free-standing highly conducting ultrananocrystalline diamond films with enhanced electron field emission properties  

NASA Astrophysics Data System (ADS)

Fabrication of free-standing/highly conducting ultrananocrystalline diamond (fc-UNCD) films at low growth temperature (<475 °C) is demonstrated. The fc-UNCD films show high conductivity of ? = 146 (? cm)-1 with superior electron field emission (EFE) properties, viz. low turn-on field of 4.35 V/?m and high EFE current density of 3.76 mA/cm2 at an applied field of 12.5 V/?m. Transmission electron microscopy examinations reveal the presence of Au/Cu clusters in film-to-substrate interface, which consequences in the induction of nanographite phases, surrounding the diamond grains that form conduction channels for electrons transport, ensuing in marvelous EFE properties of fc-UNCD films.

Sankaran, K. J.; Chen, H. C.; Lee, C. Y.; Tai, N. H.; Lin, I. N.

2012-12-01

123

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

124

Gold ion implantation induced high conductivity and enhanced electron field emission properties in ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

We report high conductivity of 185 (? cm)-1 and superior electron field emission (EFE) properties, viz. low turn-on field of 4.88 V/?m with high EFE current density of 6.52 mA/cm2 at an applied field of 8.0 V/?m in ultrananocrystalline diamond (UNCD) films due to gold ion implantation. Transmission electron microscopy examinations reveal the presence of Au nanoparticles in films, which result in the induction of nanographitic phases in grain boundaries, forming conduction channels for electron transport. Highly conducting Au ion implanted UNCD films overwhelms that of nitrogen doped ones and will create a remarkable impact to diamond-based electronics.

Sankaran, K. J.; Chen, H. C.; Sundaravel, B.; Lee, C. Y.; Tai, N. H.; Lin, I. N.

2013-02-01

125

Percolation model of an insulator-conductor transition in ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

A percolation model has been proposed to explain an insulator-conductor transition in ultrananocrystalline diamond films upon addition of nitrogen to a gas mixture used to synthesize films. An observed jump of the conductivity by 10-12 orders of magnitude is a result of the rearrangement of the structure of films leading to the formation of diamond nanorods in a graphite shell. A nitriding-induced increase in the volume fraction of these nanorods (up to 0.22) has been determined from small-angle X-ray scattering data. Conduction occurs through graphite shells and the percolation threshold corresponds to the volume fraction of conducting nanorods of 0.06.

Vlasov, I. I.; Kanzyuba, M. V.; Shiryaev, A. A.; Volkov, V. V.; Ral'chenko, V. G.; Konov, V. I.

2012-06-01

126

Piezoelectric/ultrananocrystalline diamond heterostructures for high-performance multifunctional micro/nanoelectromechanical systems.  

SciTech Connect

Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical/tribological properties, compromising applications to some devices. Diamond films with superior mechanical/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD{reg_sign}) 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 letter describes the bases of such integration and demonstration of low voltage piezoactuated hybrid PZT/UNCD cantilevers.

Srinivasan, S.; Hiller, J.; Kabius, B.; Auciello, O.

2007-01-01

127

Phosphorus ion implantation and annealing induced n-type conductivity and microstructure evolution in ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

We report n-type conductivity in phosphorus ion implanted ultrananocrystalline diamond films annealed at 800 °C and above. The amorphous carbon transits to diamond with an increase of stress after 900 °C annealing, which exhibits lower resistivity with Hall mobility of 143 cm2/Vs. After 1000 °C annealing, the diamond transits to amorphous carbon with the stress release, which has higher carrier concentration and lower Hall mobility. Both P+-implanted nano-sized diamond grains and amorphous carbon give contributions to the n-type conductivity in the films. The microstructure evolution and electrical properties are relative to the hydrogen diffusion and desorption under high temperature annealing.

Hu, X. J.; Ye, J. S.; Hu, H.; Chen, X. H.; Shen, Y. G.

2011-09-01

128

Wettability of ultrananocrystalline diamond and graphite nanowalls films: a comparison with their single crystal analogs.  

PubMed

Dramatic changes in wettability of diamond and graphite are observed when these materials are prepared in nanostructured forms--undoped and nitrogen-doped ultrananocrystalline diamond (UNCD) films, and graphite nanowalls (GNW), respectively. The nanostructured carbon films were deposited on Si by microwave plasma CVD processes. The advancing contact angle theta for water on hydrogenated undoped UNCD films increases to 106 +/- 3 degrees compared to hydrogenated single crystal diamond (theta = 92 degrees). Nitrogen doping (N2 addition to plasma) during UNCD growth makes the film more hydrophilic. The GNW films exhibited superhydrophobic behavior with theta = 144 +/- 3 degrees for water, which is higher than the contact angle of monocrystalline graphite (the basal plane) by a factor of 1.8. No chemical surface treatment is necessary to achieve such high hydrophobicity, it is accomplished solely by a specific (nanoporous, high aspect ratio) surface morphology with very low free surface energy inherent in it. The wetting behaviour of nanostructured films can be described with the Cassie-Baxter equation for heterophase nanoporous surfaces. Oxidation and hydrogenation of UNCD films make it possible to control theta over a much wider range as compared to a single crystal diamond. The influence of diamond grain size on wetting is considered taking into account the surface treatment. The corresponding variation in surface energy has been determined by the modified Young's equation. PMID:19504900

Ostrovskaya, L Y u; Ralchenko, V G; Bolshakov, A P; Saveliev, A V; Dzbanovsky, N N; Shmegera, S V

2009-06-01

129

Improvement in plasma illumination properties of ultrananocrystalline diamond films by grain boundary engineering  

NASA Astrophysics Data System (ADS)

Microstructural evolution of ultrananocrystalline diamond (UNCD) films as a function of substrate temperature (TS) and/or by introducing H2 in Ar/CH4 plasma is investigated. Variation of the sp2 and sp3 carbon content is analyzed using UV-Raman and near-edge X-ray absorption fine structure spectra. Morphological and microstructural studies confirm that films deposited using Ar/CH4 plasma at low TS consist of a random distribution of spherically shaped ultra-nano diamond grains with distinct sp2-bonded grain boundaries, which are attributed to the adherence of CH radicals to the nano-sized diamond clusters. By increasing TS, adhering efficiency of CH radicals to the diamond lattice drops and trans-polyacetylene (t-PA) encapsulating the nano-sized diamond grains break, whereas the addition of 1.5% H2 in Ar/CH4 plasma at low TS induces atomic hydrogen that preferentially etches out the t-PA attached to ultra-nano diamond grains. Both cases make the sp3-diamond phase less passivated. This leads to C2 radicals attaching to the diamond lattice promoting elongated clustered grains along with a complicated defect structure. Such a grain growth model is highly correlated to explain the technologically important functional property, namely, plasma illumination (PI) of UNCD films. Superior PI properties, viz. low threshold field of 0.21 V/?m with a high PI current density of 4.10 mA/cm2 (at an applied field of 0.25 V/?m) and high ?-coefficient (0.2604) are observed for the UNCD films possessing ultra-nano grains with a large fraction of grain boundary phases. The grain boundary component consists of a large amount of sp2-carbon phases that possibly form interconnected paths for facilitating the transport of electrons and the electron field emission process that markedly enhance PI properties.

Sankaran, K. J.; Srinivasu, K.; Chen, H. C.; Dong, C. L.; Leou, K. C.; Lee, C. Y.; Tai, N. H.; Lin, I. N.

2013-08-01

130

Chemical grafting of biphenyl self-assembled monolayers on ultrananocrystalline diamond.  

PubMed

We have investigated the formation of self-assembled monolayers (SAMs) of 4'-nitro-1,1-biphenyl-4-diazonium tetrafluoroborate (NBD) onto ultrananocrystalline diamond (UNCD) thin films. In contrast to the common approach to modify diamond and diamond-like substrates by electrografting, the SAM was formed from the saturated solution of NBD in acetonitrile by pure chemical grafting. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and near edge X-ray absorption fine structure spectroscopy (NEXAFS) have been used to verify the direct covalent attachment of the 4'-nitro-1,1-biphenyl (NB) SAM on the diamond substrate via stable C-C bonds and to estimate the monolayer packing density. The results confirm the presence of a very stable, homogeneous and dense monolayer. Additionally, the terminal nitro group of the NB SAM can be readily converted into an amino group by X-ray irradiation as well as electrochemistry. This opens the possibility of in situ electrochemical modification as well as the creation of chemical patterns (chemical lithography) in the SAM on UNCD substrates and enables a variety of consecutive chemical functionalization for sensing and molecular electronics applications. PMID:17177439

Lud, Simon Q; Steenackers, Marin; Jordan, Rainer; Bruno, Paola; Gruen, Dieter M; Feulner, Peter; Garrido, Jose A; Stutzmann, Martin

2006-12-27

131

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

132

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

2013-04-29

133

Ultrananocrystalline Diamond-Coated Microporous Silicon Nitride Membranes for Medical Implant Applications  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD) exhibits excellent biological and mechanical properties, which make it an appropriate choice for promoting epidermal cell migration on the surfaces of percutaneous implants. We deposited a ~150 nm thick UNCD film on a microporous silicon nitride membrane using microwave plasma chemical vapor deposition. Scanning electron microscopy and Raman spectroscopy were used to examine the pore structure and chemical bonding of this material, respectively. Growth of human epidermal keratinocytes on UNCD-coated microporous silicon nitride membranes and uncoated microporous silicon nitride membranes was compared using the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay. The results show that the UNCD coating did not significantly alter the viability of human epidermal keratinocytes, indicating potential use of this material for improving skin sealing around percutaneous implants.

Skoog, Shelby A.; Sumant, Anirudha V.; Monteiro-Riviere, Nancy A.; Narayan, Roger J.

2012-04-01

134

Compositional analysis of ultrananocrystalline diamond (UNCD) films using ion beam scattering  

NASA Astrophysics Data System (ADS)

Determination of the elemental composition is important to correlate the electrical and the optical properties of ultrananocrystalline diamond (UNCD) films, doped with and without nitrogen. To obtain the complete picture of impurities in the UNCD thin films, Rutherford backscattering spectroscopy (RBS), Non-Rutherford backscattering spectroscopy (NRBS), Elastic recoil detection analysis (ERDA) and nuclear reaction analysis (NRA) were performed on UNCD films on Si substrate and on free standing films. Helium beam was used for RBS and ERDA and protons were used for NRBS measurements. Exploiting the nuclear reaction of deuterons with C, O and N, 1.1 MeV D+ beam was used to quantitatively measure the concentration of these elements. Our results show that UNCD films contain less than 3% of Hydrogen while Nitrogen content incorporated in the film was estimated to be lower than 1%. The intermixing region between the substrate and the film was found to be negligible.

AlFaify, S.; Garratt, E.; Nandasiri, M. I.; Kayani, A.; Sumant, A. V.; Mancini, D. C.

2009-11-01

135

Ultrananocrystalline diamond tip integrated onto a heated atomic force microscope cantilever  

NASA Astrophysics Data System (ADS)

We report a wear-resistant ultrananocrystalline (UNCD) diamond tip integrated onto a heated atomic force microscope (AFM) cantilever and UNCD tips integrated into arrays of heated AFM cantilevers. The UNCD tips are batch-fabricated and have apex radii of approximately 10 nm and heights up to 7 ?m. The solid-state heater can reach temperatures above 600?°C and is also a resistive temperature sensor. The tips were shown to be wear resistant throughout 1.2 m of scanning on a single-crystal silicon grating at a force of 200 nN and a speed of 10 ?m s-1. Under the same conditions, a silicon tip was completely blunted. We demonstrate the use of these heated cantilevers for thermal imaging in both contact mode and intermittent contact mode, with a vertical imaging resolution of 1.9 nm. The potential application to nanolithography was also demonstrated, as the tip wrote hundreds of polyethylene nanostructures.

Kim, Hoe Joon; Moldovan, Nicolaie; Felts, Jonathan R.; Somnath, Suhas; Dai, Zhenting; Jacobs, Tevis D. B.; Carpick, Robert W.; Carlisle, John A.; King, William P.

2012-12-01

136

Ultrananocrystalline diamond tip integrated onto a heated atomic force microscope cantilever.  

PubMed

We report a wear-resistant ultrananocrystalline (UNCD) diamond tip integrated onto a heated atomic force microscope (AFM) cantilever and UNCD tips integrated into arrays of heated AFM cantilevers. The UNCD tips are batch-fabricated and have apex radii of approximately 10 nm and heights up to 7 ?m. The solid-state heater can reach temperatures above 600 °C and is also a resistive temperature sensor. The tips were shown to be wear resistant throughout 1.2 m of scanning on a single-crystal silicon grating at a force of 200 nN and a speed of 10 ?m s(-1). Under the same conditions, a silicon tip was completely blunted. We demonstrate the use of these heated cantilevers for thermal imaging in both contact mode and intermittent contact mode, with a vertical imaging resolution of 1.9 nm. The potential application to nanolithography was also demonstrated, as the tip wrote hundreds of polyethylene nanostructures. PMID:23149947

Kim, Hoe Joon; Moldovan, Nicolaie; Felts, Jonathan R; Somnath, Suhas; Dai, Zhenting; Jacobs, Tevis D B; Carpick, Robert W; Carlisle, John A; King, William P

2012-11-13

137

Nitrogen-Doped Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Pulsed Laser Deposition  

NASA Astrophysics Data System (ADS)

Nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were deposited by pulsed laser deposition. The film doped with a nitrogen content of 7.9 at. % possessed n-type conduction with an electrical conductivity of 18 ?-1\\cdotcm-1 at 300 K. A heterojunction with p-type Si exhibited typical rectifying action. The UNCD grain size was estimated to be 2.5 nm from X-ray diffraction measurement. Near-edge X-ray absorption fine-structure and Fourier transform infrared spectroscopies revealed the preferential formations of C N and C--N bonds and an enhanced amount of sp2 bonds in the films.

Al-Riyami, Sausan; Ohmagari, Shinya; Yoshitake, Tsuyoshi

2010-11-01

138

Ultrananocrystalline diamond film as an optimal cell interface for biomedical applications.  

SciTech Connect

Surfaces of materials that promote cell adhesion, proliferation, and growth are critical for new generation of implantable biomedical devices. These films should be able to coat complex geometrical shapes very conformally, with smooth surfaces to produce hermetic bioinert protective coatings, or to provide surfaces for cell grafting through appropriate functionalization. Upon performing a survey of desirable properties such as chemical inertness, low friction coefficient, high wear resistance, and a high Young's modulus, diamond films emerge as very attractive candidates for coatings for biomedical devices. A promising novel material is ultrananocrystalline diamond (UNCD{reg_sign}) in thin film form, since UNCD possesses the desirable properties of diamond and can be deposited as a very smooth, conformal coating using chemical vapor deposition. In this paper, we compared cell adhesion, proliferation, and growth on UNCD films, silicon, and platinum films substrates using different cell lines. Our results showed that UNCD films exhibited superior characteristics including cell number, total cell area, and cell spreading. The results could be attributed to the nanostructured nature or a combination of nanostructure/surface chemistry of UNCD, which provides a high surface energy, hence promoting adhesion between the receptors on the cell surface and the UNCD films.

Bajaj, P.; Akin, D.; Gupta, A.; Sherman, D.; Shi, B.; Auciello, O.; Bashir, R.; Purdue Univ.; Massachusetts General Hospital

2007-12-01

139

Ultrananocrystalline diamond film as an optimal cell interface for biomedical applications.  

PubMed

Surfaces of materials that promote cell adhesion, proliferation, and growth are critical for new generation of implantable biomedical devices. These films should be able to coat complex geometrical shapes very conformally, with smooth surfaces to produce hermetic bioinert protective coatings, or to provide surfaces for cell grafting through appropriate functionalization. Upon performing a survey of desirable properties such as chemical inertness, low friction coefficient, high wear resistance, and a high Young's modulus, diamond films emerge as very attractive candidates for coatings for biomedical devices. A promising novel material is ultrananocrystalline diamond (UNCD) in thin film form, since UNCD possesses the desirable properties of diamond and can be deposited as a very smooth, conformal coating using chemical vapor deposition. In this paper, we compared cell adhesion, proliferation, and growth on UNCD films, silicon, and platinum films substrates using different cell lines. Our results showed that UNCD films exhibited superior characteristics including cell number, total cell area, and cell spreading. The results could be attributed to the nanostructured nature or a combination of nanostructure/surface chemistry of UNCD, which provides a high surface energy, hence promoting adhesion between the receptors on the cell surface and the UNCD films. PMID:17530409

Bajaj, Piyush; Akin, Demir; Gupta, Amit; Sherman, Debby; Shi, Bing; Auciello, Orlando; Bashir, Rashid

2007-12-01

140

Tight-binding molecular-dynamics simulation of impurities in ultrananocrystalline diamond grain boundaries.  

SciTech Connect

Ultrananocrystalline diamond (UNCD) films grown from hydrogen-poor plasmas have grain sizes of 3-10 nm, resulting in a large number of grain boundaries. We repon on density-functional-based tight-binding molecular-dynamics calculations of high-energy high-angle twist (100) grain boundaries in diamond as a model for the UNCD grain boundaries. About one-half of the carbons in the grain boundary are threefold coordinated and are responsible for states introduced into the band gap. Simulations were also performed for N, Si, and H impurities in (100) twist grain boundaries where substitution energies, optimized geometries, and electronic structures were calculated. Substitution energies were found to be substantially lower for the grain boundaries compared to the bulk diamond crystal. Nitrogen increases the number of threefold-coordinated carbons while hydrogen saturates dangling bonds. The electronic structure of UNCD is characterized by a large number of states in the band gap attributed to the bonding disorder and impurities in the grain boundaries.

Zapol, P.; Sternberg, M.; Curtiss, L. A.; Frauenheim, T.; Gruen, D. M.; Universit?t Paderborn

2002-01-15

141

Development of ultrananocrystalline diamond (UNCD) coatings for multipurpose mechanical pump seals.  

SciTech Connect

The reliability and performance of silicon carbide (SiC) shaft seals on multipurpose mechanical pumps are improved by applying a protective coating of ultrananocrystalline diamond (UNCD). UNCD exhibits extreme hardness (97 GPa), low friction (0.1 in air) and outstanding chemical resistance. Consequently, the application of UNCD coatings to multipurpose mechanical pump seals can reduce frictional energy losses and eliminate the downtime and hazardous emissions from seal failure and leakage. In this study, UNCD films were prepared by microwave plasma chemical vapor deposition utilizing an argon/methane gas mixture. Prior to coating, the SiC seals were subjected to mechanical polishing using different grades of micron-sized diamond powder to produce different starting surfaces with well-controlled surface roughnesses. Following this roughening process, the seals were seeded by mechanical abrasion with diamond nanopowder, and subsequently coated with UNCD. The coated seals were subjected to dynamic wear testing performed at 3600 RPM and 100 psi for up to 10 days during which the seals were periodically removed and inspected. The UNCD-coated seals were examined using Raman microanalysis, scanning electron microscopy, optical profilometry, and adhesion testing before and after the wear testing. These analyses revealed that delamination of the UNCD films was prevented when the initial SiC seal surface had an initial roughness >0.1 {micro}m. In addition, the UNCD surfaces showed no measurable wear as compared to approximately 0.2 {micro}m of wear for the untreated SiC surfaces.

Kovalchenko, A. M.; Elam, J. W.; Erdemir, A.; Carlisle, J. A.; Auciello, O.; Libera, J. A.; Pellin, M. J.; Gruen, D. M.; Hryn, J. N. (Materials Science Division); (Georgia Inst. of Tech.)

2011-01-01

142

Improvement on the synthesis technique of ultrananocrystalline diamond films by using microwave plasma jet chemical vapor deposition  

Microsoft Academic Search

In this paper, a particular class of smooth ultrananocrystalline diamond (UNCD) films synthesized by home-made microwave plasma jet chemical vapor deposition system (MPJCVD) with gas chemistry of Ar–1%CH4–10%H2 is presented. This synthesis by MPJCVD yields UNCD films identical to those UNCD films fabricated with Ar\\/CH4 chemistry by MPCVD, but using relatively low Ar introduction, low pressure, and low power due

Chii-Ruey Lin; Wen-Hsiang Liao; Da-Hua Wei; Chien-Kuo Chang; Wei-Chuan Fang; Chi-Liang Chen; Chung-Li Dong; Jeng-Lung Chen; Jing-Hua Guo

2011-01-01

143

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

Microsoft Academic Search

In this work, the authors 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. The materials are being employed in micro- and nanoelectromechanical systems. Several reports addressed some of the mechanical properties of these materials but they are based in different experimental approaches. Here, they

H. D. Espinosa; B. Peng; N. Moldovan; T. A. Friedmann; X. Xiao; D. C. Mancini; O. Auciello; J. Carlisle; C. A. Zorman; M. Merhegany

2006-01-01

144

Spectral Absorption Properties of Ultrananocrystalline Diamond\\/Amorphous Carbon Composite Thin Films Prepared by Pulsed Laser Deposition  

Microsoft Academic Search

The spectral absorption properties of ultrananocrystalline diamond (UNCD)\\/amorphous carbon composite films grown by pulsed laser deposition with graphite were experimentally investigated. The indirect optical band gaps estimated from the absorption spectrum were 1.0 eV and approximately 5.65 eV, which correspond to those for the amorphous carbon surrounding the UNCDs and for UNCDs themselves, respectively. In addition, the spectrum revealed a

Tsuyoshi Yoshitake; Akira Nagano; Masaru Itakura; Noriyuki Kuwano; Takeshi Hara; Kunihito Nagayama

2007-01-01

145

Low-temperature magnetoresistance study of electrical transport in N- and B-doped ultrananocrystalline and nanocrystalline diamond films  

Microsoft Academic Search

In this paper, we discuss the transport mechanism in nitrogen-doped ultrananocrystalline (N-UNCD) and B-doped nanocrystalline (B-NCD) diamond thin films, which have recently attracted significant attention due to possible applications in electronics and bioelectronics. We present clear evidence that the transport in UNCD films at LHeT has low-dimensional quantum character and can be explained by a weak localisation (WL) model. Our

M. Nesladek; D. Tromson; P. Bergonzo; P. Hubik; J. J. Mares; J. Kristofik; D. Kindl; O. A. Williams; D. Gruen

2006-01-01

146

Ultrananocrystalline diamond film as a wear resistant and protective coating for mechanical seal applications.  

SciTech Connect

Mechanical shaft seals used in pumps are critically important to the safe operation of the paper, pulp, and chemical process industry, as well as petroleum and nuclear power plants. Specifically, these seals prevent the leakage of toxic gases and hazardous chemicals to the environment and final products from the rotating equipment used in manufacturing processes. Diamond coatings have the potential to provide negligible wear, ultralow friction, and high corrosion resistance for the sliding surfaces of mechanical seals, because diamond exhibits outstanding tribological, physical, and chemical properties. However, diamond coatings produced by conventional chemical vapor deposition (CVD) exhibit high surface roughness (R{sub a} {>=} 1 {mu}m), which results in high wear of the seal counterface, leading to premature seal failure. To avoid this problem, we have developed an ultrananocrystalline diamond (UNCD) film formed by a unique CH{sub 4}/Ar microwave plasma CVD method. This method yields extremely smooth diamond coatings with surface roughness R{sub a} = 20-30 nm and an average grain size of 2-5 nm. We report the results of a systematic test program involving uncoated and UNCD-coated SiC shaft seals. Results confirmed that the UNCD-coated seals exhibited neither measurable wear nor any leakage during long-duration tests that took 21 days to complete. In addition, the UNCD coatings reduced the frictional torque for seal rotation by five to six times compared with the uncoated seals. This work promises to lead to rotating shaft seals with much improved service life, reduced maintenance cost, reduced leakage of environmentally hazardous materials, and increased energy savings. This technology may also have many other tribological applications involving rolling or sliding contacts.

Sumant, A. V.; Krauss, A. R.; Gruen, D. M.; Auciello, O.; Erdemir, A.; Williams, M.; Artiles, A. F.; Adams, W.; Western Michigan Univ.; Flowserve Corp.

2005-01-01

147

Effects of Aluminum Incorporation on Diamond Grain Growth in Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition  

NASA Astrophysics Data System (ADS)

Al-incorporated ultrananocrystalline diamond/hydrogenated amorphous carbon composite films were prepared by coaxial arc plasma deposition with an Al-blended graphite target. The grain size estimated from X-ray diffraction peaks was 27 nm; this value is an order of magnitude larger than that of unincorporated films. The appearance of diamond-200 and 222 peaks, which generally disappear due to the extinction rule of diffraction, and the dilation of lattice, implied the incorporation of Al atoms into the lattices. The near-edge X-ray absorption fine-structure showed a sharp exciton peak due to diamond, which is attributed to the enlarged grains.

Katamune, Y?ki; Ohmagari, Shinya; Suzuki, Itsuroh; Yoshitake, Tsuyoshi

2012-06-01

148

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\\equivC 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

149

Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices.  

SciTech Connect

MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. A major problem with the Si-based MEMS technology is that Si has poor mechanical and tribological properties [J.J. Sniegowski, in: B. Bushan (Ed.), Tribology Issues and Opportunities in MEMS, Kluwer Academic Publisher, The Netherlands, 1998, p. 325; A.P. Lee, A.P. Pisano, M.G. Lim, Mater. Res. Soc. Symp. Proc. 276 (1992) 67.], 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 hydrophilic 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. Diamond-like films are also being investigated for application to MEMS devices. However, they involve mainly physical vapor deposition methods that are not suitable for good conformal deposition on high aspect ratio features, and generally they do not exhibit the outstanding mechanical properties of diamond. We demonstrate here the application of a novel microwave plasma technique using a unique C{sub 60}/Ar or CH{sub 4}/Ar chemistry that produces phase-pure ultrananocrystalline diamond (UNCD) coatings 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 UNCD-MEMS components, including cantilevers and multi-level devices, acting as precursors to microbearings and gears, making UNCD a promising material for the development of high performance MEMS devices.

Krauss, A. R.; Gruen, D. M.; Jayatissa, A.; Sumant, A.; Tucek, J.; Auciello, O.; Mancini, D.; Moldovan, N.; Erdemir, A.; Ersoy, D.; Gardos, M. N.; Busmann, H. G.; Meyer, E. M.; Ding, M. Q.; Univ. of Illinois at Chicago; Raytheon Electronic Systems Comp.; Fraunhofer Inst. for Applied Materials Science; Univ. of Bremen; Beijing Inst. of Electronics

2001-11-01

150

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

NASA Astrophysics Data System (ADS)

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, instead of the conventional microwave plasma. Two types of nano-diamond seed powders of similar grain sizes but with different zeta potentials were also compared. The pretreated substrate surface and the synthesized UNCD film were characterized by near edge x-ray absorption fine structure, FTIR, AFM, high-resolution scanning electron microscope, HR-TEM, and Raman spectroscopy. The electrophoretic light scattering spectroscopy was adopted to characterize the zeta potentials of the seeding suspensions and that of the substrates, respectively. Contrary to the previous report, the pretreatments deteriorated the seed density relative to that of the non-treated substrate. By contrast, the seed density was drastically improved by using a proper type of the nano-diamond seed powder. The seed density variation according to the substrate pretreatments and the type of the seed powders was attributed to the relative values of the zeta potentials of the substrates and that of the seed powders, which indicated the electrostatic nature of the seeding process. The variation of the substrate surface zeta potentials was attributed to the variation in the surface terminations induced by the respective pretreatments. The present DC-PACVD environment ensured that the secondary nucleation was also active enough to generate the densely packed UNCD grains in the growth stage. Consequently, the ultrathin, mirror-smooth and void-free UNCD film of 30 nm in thickness was enabled.

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

2011-10-01

151

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

152

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

SciTech Connect

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

153

Effect of gigaelectron volt Au-ion irradiation on the characteristics of ultrananocrystalline diamond films  

SciTech Connect

The effect of 2.245 GeV Au-ion irradiation/postannealing processes on the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films was investigated. Au-ion irradiation with a fluence of around 8.4x10{sup 13} ions/cm{sup 2} is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 deg. C for 1 h slightly degraded the EFE properties of the films but the resulting EFE behavior was still markedly superior to that of pristine UNCD films. Transmission electron microscopy examinations revealed that the EFE properties of the UNCD films are primarily improved by Au-ion irradiation/postannealing processes because of the formation of nanographites along the trajectory of the irradiating ions, which results in an interconnected path for electron transport. In contrast, the induction of grain growth process due to Au-ion irradiation in UNCD films is presumed to insignificantly degrade the EFE properties for the films as the aggregates are scarcely distributed and do not block the electron conducting path.

Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Lin, I-Nan [Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China); Sundaravel, Balakrishnan [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, Sankarakumar [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)

2010-12-15

154

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

155

Anisotropic weakly localized transport in nitrogen-doped ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

We establish the dominant effect of anisotropic weak localization (WL) in three dimensions (3D) associated with a propagative Fermi surface on the conductivity correction in heavily nitrogen-doped ultrananocrystalline diamond (UNCD) films based on magnetoresistance studies at low temperatures. Also, low-temperature electrical conductivity can show weakly localized transport in 3D combined with the effect of electron-electron interactions in these materials, which is remarkably different from the conductivity in two-dimensional WL or strong localization regime. The corresponding dephasing time of electronic wave functions in these systems described as ˜T-p with p<1 , follows a relatively weak temperature dependence compared to the generally expected nature for bulk dirty metals having p?1 . The temperature dependence of Hall (electron) mobility together with an enhanced electron density has been used to interpret the unusual magnetotransport features and show delocalized electronic transport in these n -type UNCD films, which can be described as low-dimensional superlattice structures.

Shah, Kunjal V.; Churochkin, Dmitry; Chiguvare, Zivayi; Bhattacharyya, Somnath

2010-11-01

156

Effect of gigaelectron volt Au-ion irradiation on the characteristics of ultrananocrystalline diamond films  

NASA Astrophysics Data System (ADS)

The effect of 2.245 GeV Au-ion irradiation/postannealing processes on the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films was investigated. Au-ion irradiation with a fluence of around 8.4×1013 ions/cm2 is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 °C for 1 h slightly degraded the EFE properties of the films but the resulting EFE behavior was still markedly superior to that of pristine UNCD films. Transmission electron microscopy examinations revealed that the EFE properties of the UNCD films are primarily improved by Au-ion irradiation/postannealing processes because of the formation of nanographites along the trajectory of the irradiating ions, which results in an interconnected path for electron transport. In contrast, the induction of grain growth process due to Au-ion irradiation in UNCD films is presumed to insignificantly degrade the EFE properties for the films as the aggregates are scarcely distributed and do not block the electron conducting path.

Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Sundaravel, Balakrishnan; Amirthapandian, Sankarakumar; Lin, I.-Nan

2010-12-01

157

Ion Beam Analysis Of Nitrogen Incorporated Ultrananocrystalline Diamond (UNCD) Thin Films  

NASA Astrophysics Data System (ADS)

Determination of the elemental composition is important to correlate the properties of nitrogen incorporated Ultrananocrystalline Diamond (UNCD) thin films with their growth conditions. Films were deposited by CVD deposition technology and nitrogen incorporation was introduced by diluting the growth Ar/CH4 plasma with N2 gas. Deposition of UNCD thin films was carried out on tungsten (~15 nm) coated Si substrates with varying concentrations of N2 diluted to the growth plasma. Scanning electron microscopy (SEM) and Raman spectroscopy (RS) were used to confirm the characteristic morphology of the UNCD film and its dominant sp3 bonding respectively. The deposited films were smooth on the submicron scale with the RMS roughness value of 2.9-5.1 nm. Reflectometry spectroscopy analysis (RES) technique was used to measure the films thicknesses. To obtain the elemental composition of the UNCD thin films, Rutherford Backscattering Spectrometry (RBS), Non-Rutherford Backscattering Spectrometry (NRBS), Elastic Recoil Detection Analysis (ERDA) and Nuclear Reaction Analysis (NRA) were performed. Deposited UNCD films contained less than 5 at.% of H while N content incorporated in the films was estimated to be lower than 1 at.%. The intermixing region between the substrate and the film was found to be negligible. Moreover, amorphous phase as determined by Raman analysis was found to be increasing for the sample deposited with N2.

Alfaify, S.; Garratt, E.; Dissanayake, A.; Mancini, D. C.; Kayani, A.

2011-06-01

158

Surface functionalization of ultrananocrystalline diamond films by electrochemical reduction of aryldiazonium salts.  

PubMed

The surface functionalization of ultrananocrystalline diamond (UNCD) thin films via the electrochemical reduction of aryl diazonium cations is described. The one-electron-transfer reaction leads to the formation of solution-based aryl radicals, which in turn react with the UNCD surface forming stable covalent C-C bonds. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), ac impedance spectroscopy, and contact angle measurements have been employed to characterize the organic overlayer and estimate the surface coverage. The grafting of 3,5-dichlorophenyl groups renders the UNCD surface hydrophobic, whereas the attachment of 4-aminophenyl groups makes the surface relatively hydrophilic. The surface coverage, estimated from the electrochemical and XPS measurements, is as high as 70% of a compact monolayer. The aminophenyl terminated surface was obtained by electrochemical reduction of the tethered nitrophenyl groups. This two-step approach yields a UNCD surface with functional moieties available for the potential covalent coupling of a wide variety of biomolecules (e.g., DNA and proteins). PMID:15595769

Wang, Jian; Firestone, Millicent A; Auciello, Orlando; Carlisle, John A

2004-12-21

159

In vitro and in vivo evaluation of ultrananocrystalline diamond for coating of implantable retinal microchips.  

PubMed

In this work, ultrananocrystalline diamond (UNCD) thin films were evaluated for use as hermetic and bioinert coatings for a retinal microchip. These films were deposited on highly conductive Si substrates at different temperatures (from 400 to 800 degrees C), using microwave plasma enhanced chemical vapor deposition with argon-rich Ar/CH4 gas mixtures and different relative amounts of hydrogen (0-20%). Scanning electron microscopy studies showed that all the films are dense and continuous. Results of cyclic voltammetry test revealed that when there was <2% of hydrogen in the plasma, the film obtained renders the surface electrochemically inactive, with very low leakage currents ( approximately 4 x 10(-7) A/cm2 at +/-5 V). In addition, in vivo tests of the UNCD-coated Si samples were performed by implanting them in the eyes of rabbits for 4-6 months within the eye physiological environment. According to all these results, it was concluded that UNCD is a promising candidate for use as the encapsulating coatings for implantable retinal microelectronic devices. PMID:16245292

Xiao, Xingcheng; Wang, Jian; Liu, Chao; Carlisle, John A; Mech, Brian; Greenberg, Robert; Guven, Dilek; Freda, Ricardo; Humayun, Mark S; Weiland, James; Auciello, Orlando

2006-05-01

160

Origin of platelike granular structure for the ultrananocrystalline diamond films synthesized in H2-containing Ar/CH4 plasma  

NASA Astrophysics Data System (ADS)

The modification on microstructure of diamond films due to the incorporation of H2 species into the Ar/CH4 plasma was systematically investigated. While the hydrogen-free plasma produced the ultrananocrystalline diamond films with equiaxed grains (about 5 nm in size), the hydrogen-containing plasma resulted in platelike grains (about 100×300 nm2 in size). The size of the platelike grains increased with the H2 content in the plasma. Transmission electron microscopy and optical emission spectroscopy reveal that only 0.1%H2 incorporated in the Ar/CH4 plasma is sufficient for inducing the formation of platelike grains, suggesting that the platelike grains are formed via the competition between the attachment and the etching of hydrocarbons onto the existing diamond surfaces. In Ar plasma, the diamond grains were always passivated with hydrocarbons and the active carbon species in the plasma can only renucleate to form nanocrystalline diamond grains. Incorporation of H2 species in the plasma leads to partial etching of hydrocarbons adhered onto the diamond grains, such that active carbon species in the plasma can attach to diamond surface anisotropically, resulting in diamond flakes and dendrites geometry.

Wang, Chuan-Sheng; Chen, Huang-Chin; Cheng, Hsiu-Fung; Lin, I.-Nan

2010-02-01

161

Microstructure of ultrananocrystalline diamond films grown by microwave Ar{endash}CH{sub 4} plasma chemical vapor deposition with or without added H{sub 2}  

SciTech Connect

Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar{endash}1%CH{sub 4} or Ar{endash}1%CH{sub 4}{endash}5%H{sub 2}, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2{endash}10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H{sub 2}. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2{endash}0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on the Si substrate when H{sub 2} is present in the plasma. For the case of UNCD growth from a plasma without addition of H{sub 2}, the initial nucleation occurs on an amorphous carbon layer about 10{endash}15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial. {copyright} 2001 American Institute of Physics.

Jiao, S.; Sumant, A.; Kirk, M. A.; Gruen, D. M.; Krauss, A. R.; Auciello, O.

2001-07-01

162

Microstructure of ultrananocrystalline diamond films grown by microwave Ar--CH{sub 4} plasma chemical vapor deposition with or without added H{sub 2}  

SciTech Connect

Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar--1%CH{sub 4} or Ar--1%CH{sub 4}--5%H{sub 2}, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2--10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H{sub 2}. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2--0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on the Si substrate when H{sub 2} is present in the plasma. For the case of UNCD growth from a plasma without addition of H{sub 2}, the initial nucleation occurs on an amorphous carbon layer about 10--15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial.

Jiao, S.; Sumant, A.; Kirk, M. A.; Gruen, D. M.; Krauss, A. R.; Auciello, O.

2001-07-01

163

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.

2011-01-01

164

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

165

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

PubMed

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

Seley, David B; Dissing, Daniel A; Sumant, Anirudha V; Divan, Ralu; Miller, Suzanne; Auciello, Orlando; Lepak, Lori A; Terrell, Eric A; Shogren, Tyler J; Fahrner, Daryl A; Hamilton, James P; Zach, Michael P

2011-03-21

166

Effect of titanium powder assisted surface pretreatment process on the nucleation enhancement and surface roughness of ultrananocrystalline diamond thin films  

NASA Astrophysics Data System (ADS)

A superior, easy and single-step titanium (Ti) powder assisted surface pretreatment process is demonstrated to enhance the diamond nucleation density of ultrananocrystalline diamond (UNCD) films. It is suggested that the Ti fragments attach to silicon (Si) surface form bond with carbon at a faster rate and therefore facilitates the diamond nucleation. The formation of smaller diamond clusters with higher nucleation density on Ti mixed nanodiamond powder pretreated Si substrate is found to be the main reason for smooth UNCD film surface in comparison to the conventional surface pretreatment by only nanodiamond powder ultrasonic process. The X-ray photoelectron spectroscopic study ascertains the absence of SiC on the Si surface, which suggests that the pits, defects and Ti fragments on the Si surface are the nucleation centers to diamond crystal formation. The glancing-incidence X-ray diffraction measurements from 100 nm thick UNCD films evidently show reflections from diamond crystal planes, suggesting it to be an alternative powerful technique to identify diamond phase of UNCD thin films in the absence of ultra-violet Raman spectroscopy, near-edge X-ray absorption fine structure and transmission electron microscopy techniques.

Pradhan, Debabrata; Lin, I. Nan

2009-05-01

167

Fundamentals of ultrananocrystalline diamond (UNCD) thin films as biomaterials for developmental biology: Embryonic fibroblasts growth on the surface of (UNCD) films  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films possess numerous valuable good physical, chemical and mechanical properties, making UNCD an excellent material for implantable biodevices. However, one very important property required for biomaterials i.e., biocompatibility has not been studied for UNCD. In this research, biocompatible UNCD films were synthesized. It was found that UNCD film coated substrates can dramatically promote the growth of mouse

Bing Shi; Qiaoling Jin; Liaohai Chen; Orlando Auciello

2009-01-01

168

The effect of nitrogen addition to Ar\\/CH 4 plasmas on the growth, morphology and field emission of ultrananocrystalline diamond  

Microsoft Academic Search

The effect of the addition of nitrogen to plasmas during the CVD growth of diamond films on field emission properties has been studied. Ultrananocrystalline diamond with 5–15 nm grain size has been grown with the incorporation of nitrogen up to 8×1020 atoms\\/cm3. Field emission onsets as low as 2 V\\/?m have been achieved. UV Raman and electron energy loss spectroscopy

T. D. Corrigan; D. M. Gruen; A. R. Krauss; P. Zapol; R. P. H. Chang

2002-01-01

169

Fabrication of an ultra-nanocrystalline diamond-coated silicon wire array with enhanced field-emission performance  

NASA Astrophysics Data System (ADS)

Large-area ultra-nanocrystalline diamond-coated silicon nanowire (UNCD/SiNW) field-emitter arrays were prepared by the deposition of ultra-nanocrystalline diamond (UNCD) on the tips of arrays of silicon nanowires (SiNWs) with uniform diameters. The electron field-emission (EFE) behavior of UNCD/SiNW arrays as well as that of the SiNW arrays has been observed. The SiNWs exhibit good electron field-emission properties with turn-on fields (E0) of about 7.6 V µm-1, which is superior to the EFE properties of planar-silicon materials. The turn-on fields are related to the diameter of the SiNWs. Coating the SiNWs with a UNCD film further improves their EFE properties. The threshold field for attaining Je = 0.1 mA cm-2 EFE current density is 16.0 V µm-1 for bare SiNWs and 10.2 V µm-1 for UNCD/SiNWs. The improvement in EFE properties due to the UNCD coating is presumably due to the lower work function of field emission of the UNCD materials, compared to that of the silicon materials.

Tzeng, Yu-Fen; Liu, Kao-Hsiang; Lee, Yen-Chih; Lin, Sue-Jian; Lin, I.-Nan; Lee, Chi-Young; Chiu, Hsin-Tien

2007-10-01

170

Synthesis and characterization of smooth ultrananocrystalline diamond films via low pressure bias-enhanced nucleation and growth.  

SciTech Connect

This letter describes the fundamental process underlying the synthesis of ultrananocrystalline diamond (UNCD) films, using a new low-pressure, heat-assisted bias-enhanced nucleation (BEN)/bias enhanced growth (BEG) technique, involving H{sub 2}/CH{sub 4} gas chemistry. This growth process yields UNCD films similar to those produced by the Ar-rich/CH{sub 4} chemistries, with pure diamond nanograins (3-5 nm), but smoother surfaces ({approx}6 nm rms) and higher growth rate ({approx}1 {micro}m/h). Synchrotron-based x-Ray absorption spectroscopy, atomic force microscopy, and transmission electron microscopy studies on the BEN-BEG UNCD films provided information critical to understanding the nucleation and growth mechanisms, and growth condition-nanostructure-property relationships.

Chen, Y. C.; Zhong, X. Y.; Koniceek, A. R.; Grierson, D. S.; Tai, N. H.; Lin, I. N.; Kabius, B.; Hiller, J. M.; Sumant, A. V.; Carpick, R. W.; Auciello, O.; National Tsing-Hua Univ.; Univ. of Wisconsin at Madison; Tamkang Univ.; Univ. Pennsylvania

2008-03-31

171

n-type conductivity and phase transition in ultrananocrystalline diamond films by oxygen ion implantation and annealing  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD) films were implanted by oxygen ion and annealed at different temperatures. The electrical and structrual properties of O+-implanted UNCD films were investigated by Hall effects, high-resolution transmission electron microscopy (HRTEM) and uv Raman spectroscopy measurements. The results show that O+-implanted nano-sized diamond grains annealed at 800 °C and above give n-type conductivity to the sample and the UNCD film exhibits n-type resistivity with the carrier mobility of 1~11 cm2 V-1s-1. With O+ dose increasing from 1015 to 1016 cm-2, diamond phase transits to the amorphous carbon phase accompanied by n-type semiconduction transforming to metallic conduction. In the 1014 cm-2 O+-implanted UNCD film, some amorphous carbon at grain boundaries transits to diamond phase with annealing temperature (Ta) increasing from 500 °C to 800-900 °C, and some of diamond grains are found to be converted to amorphous carbon phase again after 1000 °C annealing. This phase transition is closely relative to the n-type conductivity of the UNCD films, in which n-type conductivity increases with the amorphous carbon phase transiting to diamond phase in the Ta range of 500-900 °C, and it decreases with diamond phase transiting to amorphous carbon phase in the case of 1000 °C annealing. It is indicated that the O+-implanted nano-sized diamond grains dominantly control the n-type conductivity of UNCD film in the Ta range of 800-900 °C, while the grain-boundary-conduction controls the n-type conductivty in UNCD film annealed at 1000 °C. In this case, a novel conduction mechanism that O+-implanted nano-sized diamond grains supply n-type conductivity and the amorphous carbon grain boundaries give a current path to the UNCD films is proposed.

Hu, X. J.; Ye, J. S.; Liu, H. J.; Shen, Y. G.; Chen, X. H.; Hu, H.

2011-03-01

172

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

173

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

174

Improvement on the synthesis technique of ultrananocrystalline diamond films by using microwave plasma jet chemical vapor deposition  

NASA Astrophysics Data System (ADS)

In this paper, a particular class of smooth ultrananocrystalline diamond (UNCD) films synthesized by home-made microwave plasma jet chemical vapor deposition system (MPJCVD) with gas chemistry of Ar-1%CH4-10%H2 is presented. This synthesis by MPJCVD yields UNCD films identical to those UNCD films fabricated with Ar/CH4 chemistry by MPCVD, but using relatively low Ar introduction, low pressure, and low power due to the focused microwave plasma jet enhanced the dissociation of react gases to form energetic species during the deposition. The transition from microcrystalline to ultrananocrystalline diamond films grown from Ar/Ar+H2 0% to 90% plasmas using MPJCVD has been systematically studied. The results of this study showed that the grain size, surface roughness, and sp3 bonding carbon concentration in the films decreased with the increase in Ar concentration. The reason is due to the great increase in renucleation during the films growth. The TEM images clearly exhibited the grain size of the films (Ar/Ar+H2: 90%) in the range of 3-8 nm. The near-edge X-ray absorption fine structure spectrum also exhibited the clear bonding characteristics of diamond. Moreover, the plasma precarbonization was employed by MPJCVD prior to UNCD films synthesis in order to markedly enhance the smoothness of UNCD films. The UNCD film was synthesized via unique MPJCVD-enhanced nucleation and growth, which produced films with high growth rate (315 nm/h), smooth surfaces (˜11.7 nm rms), and extremely fine-grained (3-8 nm) distribution in the whole film.

Lin, Chii-Ruey; Liao, Wen-Hsiang; Wei, Da-Hua; Chang, Chien-Kuo; Fang, Wei-Chuan; Chen, Chi-Liang; Dong, Chung-Li; Chen, Jeng-Lung; Guo, Jing-Hua

2011-07-01

175

Modification of ultrananocrystalline diamond film microstructure via Fe-coating and annealing for enhancement of electron field emission properties  

NASA Astrophysics Data System (ADS)

The interaction between Fe-coatings and ultrananocrystalline diamond (UNCD) films during annealing was investigated in detail using transmission electron microscopy. The thin Fe-coating first formed nanosized Fe-clusters and then catalytically dissociated the diamond, re-precipitating carbon to form nanosized graphite clusters. These clusters formed conducting networks that facilitated electron transport and greatly improved the electron field emission (EFE) properties of the UNCD films. The extent of enhancement varied markedly with annealing temperature and atmosphere. For H2-annealed films, EFE behavior was optimized by annealing at 900 °C. EFE was turned on at (E0)H2 = 1.2 V/?m, attaining EFE current density of (Je)H2 = 772.0 ?A/cm2 at an applied field of 8.8 V/mm. These characteristics were superior to those of UNCD films NH3-annealed at 850 °C. The inferior EFE properties for the NH3-annealed samples were attributed to reaction of NH3 with the hydrocarbon phase that encapsulated the nanosized diamond grains, hindering Fe-diamond interaction.

Teng, Kuang-Yau; Shih, Wen-Ching; Huang, Pin-Chang; Chen, Huang-Chin; Tang, Chen-Yau; Lin, I.-Nan

2012-08-01

176

Effects of Hydrogen and Nitrogen Atmospheres on Growth of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films by Reactive Pulsed Laser Deposition  

NASA Astrophysics Data System (ADS)

The growth of ultrananocrystalline diamond/nonhydrogenated amorphous carbon composite films was realized by pulsed laser deposition with a graphite target in a nitrogen atmosphere totally excluding hydrogen. The existence of 7 nm diamond grains was confirmed by X-ray diffraction. Nitrogen incorporation into the films was confirmed by X-ray photoemission and near-edge X-ray absorption structure spectroscopies, and the nitrogenation produced n-type conduction with an electrical conductivity of 0.2 ?-1\\cdot cm-1 at 300 K. The results of study proved that nitrogen acts as a reactive gas for the formation of diamond grains, similarly to hydrogen.

Al-Riyami, Sausan; Shaban, Mahmoud; Gima, Hiroki; Yoshitake, Tsuyoshi

2013-06-01

177

Deep-Ultraviolet Light Detection of p-Type Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films  

NASA Astrophysics Data System (ADS)

Deep-ultraviolet (DUV) light detection of p-type ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films prepared by pulsed laser deposition was investigated. The photocurrent spectra revealed that the UNCD/a-C:H films possess strong responses in the wavelength range between 210 and 280 nm, which might originate from UNCD grains. The heterojunction photodiodes comprised of p-type UNCD/a-C:H and n-type Si exhibited an obvious photovoltaic action for 254 nm DUV light illumination. The external quantum efficiency and responsivity of the photodiodes were estimated to be 71% and 130 mA/W, respectively. It was proved that UNCD/a-C:H is a new promising material applicable to DUV photodetectors.

Ohmagari, Shinya; Yoshitake, Tsuyoshi

2012-06-01

178

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

179

Oxygen Ion Implantation Enhanced Silicon-Vacancy Photoluminescence and n-Type Conductivity of Ultrananocrystalline Diamond Films  

NASA Astrophysics Data System (ADS)

We report the enhanced silicon-vacancy (Si-V) photoluminescence (PL) intensity and n-type conductivity of ultrananocrystalline diamond (UNCD) films by oxygen ion (O+) implantation. With O+ dose increasing from 1014 to 1015 cm-2, the PL intensity and n-type conductivity significantly increase by 6 and 45 times, respectively, after 1000°C annealing. The secondary ion mass spectroscopy mapping measurements show that the content of oxygen is larger in the zone, which has larger content of silicon, indicating that oxygen tends to adhere to silicon. It is suggested that oxygen related Si-V defects are formed, which will enhance the PL intensity and n-type conductivity of UNCD films.

Hu, Xiao-Jun; Li, Nian

2013-08-01

180

Formation of p-Type Semiconducting Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films by Boron Doping  

NASA Astrophysics Data System (ADS)

p-Type ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films were fabricated by pulsed laser deposition using boron-doped graphite targets. Thermal analysis confirmed the occurrence of p-type conduction. The electrical conductivity increased with the doped amount of boron. An activation energy estimated from the Arrhenius plot was approximately 0.1 eV. Near-edge X-ray absorption fine structure spectra revealed that the ?*C-H peak weakened and the ?*C-B peak strengthened with an increase in the doped amount of boron. Fourier transform infrared spectroscopy showed that the sp3 C-H peak weakened with the doped amount of boron. These probably indicate that the hydrogen atoms that terminate the dangling bonds of UNCD crystallites are partially replaced with boron atoms.

Shinya Ohmagari,; Tsuyoshi Yoshitake,; Akira Nagano,; Ryota Ohtani,; Hiroyuki Setoyama,; Eiichi Kobayashi,; Takeshi Hara,; Kunihito Nagayama,

2010-03-01

181

Hydrogenation Effects of Ultrananocrystalline Diamond Detected by X-ray Absorption Near Edge Structure and Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Nitrogen-doped ultrananocrystalline diamond (UNCD) thin films functionalized with H2 are significantly affected by the sp2 hybridized carbon defects that are detected and analyzed using X-ray absorption near edge structure (XANES) and Raman spectroscopy using two different excitation wavelengths. The XANES and Raman results provide evidence for the presence of aromatic hydrocarbons and sp2 amorphous matrix in the grain boundaries when UNCD films are functionalized with H2. These hydrocarbons increase on hydrogenation leading to a decrease of the sp2-carbon defects (?* C=C bond) and an increase of sp3-carbon (?* C--C bond). This sp3-carbon (?* C--C bond) is evidently responsible for UNCD crystallites existence in the film structure and hence change the structural integrity, electronic structure, electrical and bonding properties.

Ray, Sekhar C.; Erasmus, Rudolph M.; Tsai, H. M.; Pao, C. W.; Lin, I.-N.; Pong, W. F.

2012-09-01

182

Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet  

PubMed Central

This paper describes a new low-temperature process underlying the synthesis of highly transparent ultrananocrystalline diamond [UNCD] films by low-pressure and unheated microwave plasma jet-enhanced chemical vapor deposition with Ar-1%CH4-10%H2 gas chemistry. The unique low-pressure/low-temperature [LPLT] plasma jet-enhanced growth even with added H2 and unheated substrates yields UNCD films similar to those prepared by plasma-enhanced growth without addition of H2 and heating procedure. This is due to the focused plasma jet which effectively compensated for the sluggish kinetics associated with LPLT growth. The effects of pressure on UNCD film synthesis from the microwave plasma jet were systematically investigated. The results indicated that the substrate temperature, grain size, surface roughness, and sp3 carbon content in the films decreased with decreasing pressure. The reason is due to the great reduction of H? emission to lower the etching of sp2 carbon phase, resulting from the increase of mean free path with decreasing pressure. We have demonstrated that the transition from nanocrystalline (80 nm) to ultrananocrystalline (3 to 5 nm) diamond films grown via microwave Ar-1%CH4-10%H2 plasma jets could be controlled by changing the pressure from 100 to 30 Torr. The 250-nm-thick UNCD film was synthesized on glass substrates (glass transition temperature [Tg] 557°C) using the unique LPLT (30 Torr/460°C) microwave plasma jet, which produced UNCD films with a high sp3 carbon content (95.65%) and offered high optical transmittance (approximately 86% at 700 nm).

2012-01-01

183

Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet.  

PubMed

This paper describes a new low-temperature process underlying the synthesis of highly transparent ultrananocrystalline diamond [UNCD] films by low-pressure and unheated microwave plasma jet-enhanced chemical vapor deposition with Ar-1%CH4-10%H2 gas chemistry. The unique low-pressure/low-temperature [LPLT] plasma jet-enhanced growth even with added H2 and unheated substrates yields UNCD films similar to those prepared by plasma-enhanced growth without addition of H2 and heating procedure. This is due to the focused plasma jet which effectively compensated for the sluggish kinetics associated with LPLT growth. The effects of pressure on UNCD film synthesis from the microwave plasma jet were systematically investigated. The results indicated that the substrate temperature, grain size, surface roughness, and sp3 carbon content in the films decreased with decreasing pressure. The reason is due to the great reduction of H? emission to lower the etching of sp2 carbon phase, resulting from the increase of mean free path with decreasing pressure. We have demonstrated that the transition from nanocrystalline (80 nm) to ultrananocrystalline (3 to 5 nm) diamond films grown via microwave Ar-1%CH4-10%H2 plasma jets could be controlled by changing the pressure from 100 to 30 Torr. The 250-nm-thick UNCD film was synthesized on glass substrates (glass transition temperature [Tg] 557°C) using the unique LPLT (30 Torr/460°C) microwave plasma jet, which produced UNCD films with a high sp3 carbon content (95.65%) and offered high optical transmittance (approximately 86% at 700 nm). PMID:22260391

Liao, Wen-Hsiang; Wei, Da-Hua; Lin, Chii-Ruey

2012-01-19

184

Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet  

NASA Astrophysics Data System (ADS)

This paper describes a new low-temperature process underlying the synthesis of highly transparent ultrananocrystalline diamond [UNCD] films by low-pressure and unheated microwave plasma jet-enhanced chemical vapor deposition with Ar-1%CH4-10%H2 gas chemistry. The unique low-pressure/low-temperature [LPLT] plasma jet-enhanced growth even with added H2 and unheated substrates yields UNCD films similar to those prepared by plasma-enhanced growth without addition of H2 and heating procedure. This is due to the focused plasma jet which effectively compensated for the sluggish kinetics associated with LPLT growth. The effects of pressure on UNCD film synthesis from the microwave plasma jet were systematically investigated. The results indicated that the substrate temperature, grain size, surface roughness, and sp 3 carbon content in the films decreased with decreasing pressure. The reason is due to the great reduction of H ? emission to lower the etching of sp 2 carbon phase, resulting from the increase of mean free path with decreasing pressure. We have demonstrated that the transition from nanocrystalline (80 nm) to ultrananocrystalline (3 to 5 nm) diamond films grown via microwave Ar-1%CH4-10%H2 plasma jets could be controlled by changing the pressure from 100 to 30 Torr. The 250-nm-thick UNCD film was synthesized on glass substrates (glass transition temperature [ T g] 557°C) using the unique LPLT (30 Torr/460°C) microwave plasma jet, which produced UNCD films with a high sp 3 carbon content (95.65%) and offered high optical transmittance (approximately 86% at 700 nm).

Liao, Wen-Hsiang; Wei, Da-Hua; Lin, Chii-Ruey

2012-01-01

185

Origin of a needle-like granular structure for ultrananocrystalline diamond films grown in a N2/CH4 plasma  

NASA Astrophysics Data System (ADS)

Microstructural evolution as a function of substrate temperature (TS) for conducting ultrananocrystalline diamond (UNCD) films is systematically studied. Variation of the sp2 graphitic and sp3 diamond content with TS in the films is analysed from the Raman and near-edge x-ray absorption fine structure spectra. Morphological and microstructural studies confirm that at TS = 700 °C well-defined acicular structures evolve. These nanowire structures comprise sp3 phased diamond, encased in a sheath of sp2 bonded graphitic phase. TS causes a change in morphology and thereby the various properties of the films. For TS = 800 °C the acicular grain growth ceases, while that for TS = 700 °C ceases only upon termination of the deposition process. The grain-growth process for the unique needle-like granular structure is proposed such that the CN species invariably occupy the tip of the nanowire, promoting an anisotropic grain-growth process and the formation of acicular structure of the grains. The electron field emission studies substantiate that the films grown at TS = 700 °C are the most conducting, with conduction mediated through the graphitic phase present in the films.

Sankaran, K. J.; Kurian, J.; Chen, H. C.; Dong, C. L.; Y Lee, C.; Tai, N. H.; Lin, I. N.

2012-09-01

186

Near-Edge X-ray Absorption Fine-Structure, X-ray Photoemission, and Fourier Transform Infrared Spectroscopies of Ultrananocrystalline Diamond\\/Hydrogenated Amorphous Carbon Composite Films  

Microsoft Academic Search

The chemical bonding structure of ultrananocrystalline diamond (UNCD)\\/hydrogenated amorphous carbon (a-C:H) composite films prepared by pulsed laser deposition was examined by near-edge X-ray absorption fine-structure (NEXAFS), X-ray photoemission, and Fourier transform infrared (FTIR) spectroscopies. An intense sp3-CH peak was observed in the FTIR spectrum. This implies that the sp3-CH peak originates from the grain boundaries between UNCD crystallites, wherein dangling

Tsuyoshi Yoshitake; Akira Nagano; Shinya Ohmagari; Masaru Itakura; Noriyuki Kuwano; Ryota Ohtani; Hiroyuki Setoyama; Eiichi Kobayashi; Kunihito Nagayama

2009-01-01

187

Microstructure of ultrananocrystalline diamond films grown by microwave ArCH4 plasma chemical vapor deposition with or without added H2  

Microsoft Academic Search

Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar-1%CH4 or Ar-1%CH4-5%H2, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2-10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H2. High resolution electron microscopy shows no evidence

S. Jiao; A. Sumant; M. A. Kirk; D. M. Gruen; A. R. Krauss; O. Auciello

2001-01-01

188

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

189

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

190

Fundamentals and technology for monolithically integrated RF MEMS switches with ultra-nanocrystalline diamond dielectric/CMOS devices  

NASA Astrophysics Data System (ADS)

Most current capacitive RF-MEMS switch technology is based on conventional dielectric materials such as SiO2 and Si3N4. However, they suffer not only from charging problems but also stiction problems leading to premature failure of an RF-MEMS switch. Ultrananocrystalline diamond (UNCD(R) (2-5 nm grains) and nanocrystalline diamond (NCD) (10- 100 nm grains) films exhibit one of the highest Young's modulus (~ 980-1100 GPa) and demonstrated MEMS resonators with the highest quality factor (Q >=10,000 in air for NCD) today, they also exhibit the lowest force of adhesion among MEMS/NEMS materials (~10 mJ/m2-close to van der Waals' attractive force for UNCD) demonstrated today. Finally, UNCD exhibits dielectric properties (fast discharge) superior to those of Si and SiO2, as shown in this paper. Thus, UNCD and NCD films provide promising platform materials beyond Si for a new generation of important classes of high-performance MEMS/NEMS devices.

Auciello, O.; Sumant, A. V.; Goldsmith, C.; O'Brien, S.; Sampath, S.; Gudeman, C.; Wang, W.; Hwang, J. C. M.; Swonger, J.; Carlisle, J. A.; Balachandran, S.; Mancini, D. C.

2010-04-01

191

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

192

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

193

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

194

High efficiency diamond solar cells  

DOEpatents

A photovoltaic device and method of making same. A layer of p-doped microcrystalline diamond is deposited on a layer of n-doped ultrananocrystalline diamond such as by providing a substrate in a chamber, providing a first atmosphere containing about 1% by volume CH.sub.4 and about 99% by volume H.sub.2 with dopant quantities of a boron compound, subjecting the atmosphere to microwave energy to deposit a p-doped microcrystalline diamond layer on the substrate, providing a second atmosphere of about 1% by volume CH.sub.4 and about 89% by volume Ar and about 10% by volume N.sub.2, subjecting the second atmosphere to microwave energy to deposit a n-doped ultrananocrystalline diamond layer on the p-doped microcrystalline diamond layer. Electrodes and leads are added to conduct electrical energy when the layers are irradiated.

Gruen, Dieter M. (Downers Grove, IL)

2008-05-06

195

Enhanced Growth of Diamond Grains in Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films by Pulsed Laser Deposition with Boron-Blended Graphite Targets  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon composite films were prepared by pulsed laser deposition with boron-blended graphite targets and the effects of the boron-doping on the growth of UNCD grains were investigated. With an increase in the boron content, the grain size was increased from 5 to 23 nm accompanied by the lattice constant approaching that of bulk diamond. The sp3/(sp3+ sp2) ratio estimated from the X-ray photoemission spectra was enhanced by the boron-doping, which might be predominantly attributable to the enlarged grains. The near-edge X-ray absorption fine-structure spectroscopic measurement revealed that boron atoms are preferentially distributed into grain boundaries. On the basis of the results, the roles of the boron atoms in the enhanced crystalline growth are discussed. We consider that the crystalline growth posterior to the nucleation is facilitated by boron atoms neighboring UNCD grains or by boron-containing energetic species in plasma.

Ohmagari, Shinya; Katamune, Y?ki; Ichinose, Hikaru; Yoshitake, Tsuyoshi

2012-02-01

196

Improvement of field emission performance on nitrogen ion implanted ultrananocrystalline diamond films through visualization of structure modificaitons.  

SciTech Connect

The relationship between the electron field emission properties and structure of ultra-nanocrystalline diamond (UNCD) films implanted by nitrogen ions or carbon ions was investigated. The electron field emission properties of nitrogen-implanted UNCD films and carbon-implanted UNCD films were pronouncedly improved with respect to those of as-grown UNCD films, that is, the turn-on field decreased from 23.2 V/{micro}m to 12.5 V/{micro}m and the electron field emission current density increased from 10E-5 mA/cm{sup 2} to 1 x 10E-2 mA/cm{sup 2}. The formation of a graphitic phase in the nitrogen-implanted UNCD films was demonstrated by Raman microscopy and cross-sectional high-resolution transmission electron microscopy. The possible mechanism is presumed to be that the nitrogen ion irradiation induces the structure modification (converting sp{sup 3}-bonded carbons into sp{sup 2}-bonded ones) in UNCD films.

Chen, Y.-C.; Zhong, X-Y.; Kabius, B.; Hiller, J. M.; Tai, N.-H.; Lin, I.-N. (Materials Science Division); (National Tsing-Hua Univ.); (Tamkang Univ.)

2011-02-01

197

A quantitative study of detection mechanism of a label-free impedance biosensor using ultrananocrystalline diamond microelectrode array.  

PubMed

It is well recognized that label-free biosensors are the only class of sensors that can rapidly detect antigens in real-time and provide remote environmental monitoring and point-of-care diagnosis that is low-cost, specific, and sensitive. Electrical impedance spectroscopy (EIS) based label-free biosensors have been used to detect a wide variety of antigens including bacteria, viruses, DNA, and proteins due to the simplicity of their detection technique. However, their commercial development has been hindered due to difficulty in interpreting the change in impedance upon antigen binding and poor signal reproducibility as a result of surface fouling and non-specific binding. In this study, we develop a circuit model to adequately describe the physical changes at bio functionalized surface and provide an understanding of the detection mechanism based on electron exchange between electrolyte and surface through pores surrounding antibody-antigen. The model was successfully applied to extract quantitative information about the bio surface at different stages of surface functionalization. Further, we demonstrate boron-doped ultrananocrystalline diamond (UNCD) microelectrode array (3 × 3 format, 200 ?m diameter) improves signal reproducibility significantly and increases sensitivity by four orders of magnitude. This study marks the first demonstration of UNCD array based biosensor that can reliably detect a model Escherichia coli K12 bacterium using EIS, positioning this technology for rapid adoption in point-of-use applications. PMID:22456097

Siddiqui, Shabnam; Dai, Zhenting; Stavis, Courtney J; Zeng, Hongjun; Moldovan, Nicolaie; Hamers, Robert J; Carlisle, John A; Arumugam, Prabhu U

2012-03-10

198

Construction of a ultrananocrystalline diamond-based cold cathode arrays for a flat-panel x-ray source  

NASA Astrophysics Data System (ADS)

A novel cold cathode field emission array (FEA) X-ray source based on ultra-nanocrystalline diamond (UNCD) field emitters is being constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation the flat-panel X-ray source could be used in tomography, radiography, or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube "forest" (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA. This work includes the first generation of the UNCD based FEA prototype which is being manufactured at the Center for Nanoscale Materials within Argonne National Laboratory with standard microfabrication techniques. The prototype is a 3x3 pixel FEA, with a pixel pitch of 500 ?m, where each pixel is individually controllable.

Grant, E. J.; Posada, C. M.; Divan, R.; Sumant, A. V.; Rosenmann, D.; Stan, L.; Avachat, A.; Castano, C. H.; Lee, H. K.

2013-06-01

199

Heterojunction Diodes Comprised of n-Type Silicon and p-Type Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite  

NASA Astrophysics Data System (ADS)

Heterojunction diodes comprised of p-type ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) and n-type Si, wherein 3 at. % boron-doped UNCD/a-C:H films were deposited on Si substrates by pulsed laser deposition, were electrically studied. The current--voltage (I--V) characteristics showed the typical rectification action with a leakage current density of 4.7 × 10-5 A/cm2 at a reverse voltage of -1 V. The carrier transport is expected to be in generation--recombination process accompanied by tunneling at low forward voltages of 0.1--0.5 V, and to be predominantly in tunneling at 0.5--1.0 V, from ideality factors estimated from the forward I--V curve. Grain boundaries in the UNCD/a-C:H film might act as centers for tunneling. From the capacitance--voltage measurement, the build-in potential of the heterojunction and an active carrier concentration in the p-type UNCD/a-C:H film were estimated to be 0.6 eV and 1.4 × 1017 cm-3, respectively.

Ohmagari, Shinya; Al-Riyami, Sausan; Yoshitake, Tsuyoshi

2011-03-01

200

p-Type Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Pulsed Laser Deposition and Their Application to Photodetectors  

NASA Astrophysics Data System (ADS)

p-Type ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were fabricated by pulsed laser deposition with boron-blended graphite targets. The X-ray diffraction patterns exhibited diffraction peaks attributable to diamond-111 and diamond-200. Electrical conductivity clearly increased with boron content. The near-edge X-ray absorption fine structure revealed that doped boron atoms partially replace hydrogen atoms that terminate the dangling bonds of UNCD grains. Heterojunction diodes comprising p-type UNCD/a-C:H and n-type Si showed a strong photoresponse that originates from UNCD grains in the wavelength range between 200 and 280 nm. We experimentally proved that boron-doped UNCD/a-C:H is a new promising p-type semiconductor for photodetection.

Ohmagari, Shinya; Yoshitake, Tsuyoshi

2012-09-01

201

N -type electric conductivity of nitrogen-doped ultrananocrystalline diamond films  

Microsoft Academic Search

The electronic structures of several possible nitrogen-related centers on the diamond surface and in the diamond grain-boundary have been studied using density functional theory approaches with cluster models. The results indicate that the nitrogen-vacancy related complex may be the shallow donor center, and the complexes of nitrogen and dangling bond or nitrogen with a pi bond may play the role

Ying Dai; Dadi Dai; Cuixia Yan; Baibiao Huang; Shenghao Han

2005-01-01

202

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

203

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

204

Influence of surface passivation on the friction and wear behavior of ultrananocrystalline diamond and tetrahedral amorphous carbon thin films  

NASA Astrophysics Data System (ADS)

Highly sp3-bonded, nearly hydrogen-free carbon-based materials can exhibit extremely low friction and wear in the absence of any liquid lubricant, but this physical behavior is limited by the vapor environment. The effect of water vapor on friction and wear is examined as a function of applied normal force for two such materials in thin film form: one that is fully amorphous in structure (tetrahedral amorphous carbon, or ta-C) and one that is polycrystalline with <10 nm grains [ultrananocrystalline diamond (UNCD)]. Tribologically induced changes in the chemistry and carbon bond hybridization at the surface are correlated with the effect of the sliding environment and loading conditions through ex situ, spatially resolved near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. At sufficiently high relative humidity (RH) levels and/or sufficiently low loads, both films quickly achieve a low steady-state friction coefficient and subsequently exhibit low wear. For both films, the number of cycles necessary to reach the steady-state is progressively reduced for increasing RH levels. Worn regions formed at lower RH and higher loads have a higher concentration of chemisorbed oxygen than those formed at higher RH, with the oxygen singly bonded as hydroxyl groups (C-OH). While some carbon rehybridization from sp3 to disordered sp2 bonding is observed, no crystalline graphite formation is observed for either film. Rather, the primary solid-lubrication mechanism is the passivation of dangling bonds by OH and H from the dissociation of vapor-phase H2O. This vapor-phase lubrication mechanism is highly effective, producing friction coefficients as low as 0.078 for ta-C and 0.008 for UNCD, and wear rates requiring thousands of sliding passes to produce a few nanometers of wear.

Konicek, A. R.; Grierson, D. S.; Sumant, A. V.; Friedmann, T. A.; Sullivan, J. P.; Gilbert, P. U. P. A.; Sawyer, W. G.; Carpick, R. W.

2012-04-01

205

Effect of nitrogen addition to Ar/CH{sub 4} plasmas on the growth, morphology and field emission of ultrananocrystalline diamond.  

SciTech Connect

The effect of the addition of nitrogen to plasmas during the CVD growth of diamond films on field emission properties has been studied. Ultrananocrystalline diamond with 5-15 nm grain size has been grown with the incorporation of nitrogen up to 8 x 10{sup 20} atoms/cm{sup 3}. Field emission onsets as low as 2 V/{mu}m have been achieved. UV Raman and electron energy loss spectroscopy (EELS) measurements show an increase in the sp{sup 2} content in the films with nitrogen in the plasma compared to films without N{sub 2} addition. A model is discussed in which the nitrogen preferentially enters the grain boundaries and promotes sp{sup 2} bonding in the neighboring carbon atoms. The increase in the sp{sup 2} content appears to improve the field emission properties of the films.

Corrigan, T. D.; Gruen, D. M.; Krauss, A. R.; Zapol, P.; Chang, R. P. H.; Northwestern Univ.

2002-01-01

206

Ultrananocrystalline Diamond Film as a Wear-Resistant and Protective Coating for Mechanical Seal Applications  

Microsoft Academic Search

Mechanical shaft seals used in pumps are critically important to the safe operation of the paper, pulp, and chemical process industry, as well as petroleum and nuclear power plants. Specifically, these seals prevent the leakage of toxic gases and hazardous chemicals to the environment and final products from the rotating equipment used in manufacturing processes. Diamond coatings have the potential

A. V. Sumant; A. R. Krauss; D. M. Gruen; O. Auciello; A. Erdemir; M. Williams; A. F. Artiles; W. Adams; Flowserve Corp

2005-01-01

207

Charge-based deep level transient spectroscopy of undoped and nitrogen-doped ultrananocrystalline diamond films  

Microsoft Academic Search

A comparative study of electrically active defects has been performed for undoped and nitrogen-doped nanocrystalline diamond thin films deposited on Si substrates from CH4\\/Ar\\/H2 and CH4\\/Ar\\/N2 gas mixtures using microwave and d.c. plasma CVD techniques. The method of charge-based deep level transient spectroscopy (Q-DLTS) was applied to obtain information on the concentration, activation energy and capture cross-section of native and

V. I Polyakov; A. I Rukovishnikov; N. M Rossukanyi; V. G Pereverzev; S. M Pimenov; J. A Carlisle; D. M Gruen; E. N Loubnin

2003-01-01

208

Mechanical Properties of Ultrananocrystalline Diamond Thin Films Relevant to MEMS\\/NEMS Devices  

Microsoft Academic Search

The mechanical properties of ultrananocrys- talline diamond (UNCD) thin films were measured using mi- crocantilever deflection and membrane deflection techniques. Bending tests on several free-standing UNCD cantilevers, 0.5 µm thick, 20 µm wide and 80 µm long, yielded elastic modulus values of 916-959 GPa. The tests showed good re- producibility by repeated testing on the same cantilever and by testing

Horacio Dante Espinosa; Barton C Prorok; Bei Peng; Keun-Ho Kim; Nicolaie Moldovan; Orlando Auciello; John A Carlisle; Dieter M. Gruen; Derrick C Mancini

2003-01-01

209

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 ?s, 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

210

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

211

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

212

Effect of CH4 concentration on the growth behavior, structure, and transparent properties of ultrananocrystalline diamond films synthesized by focused microwave Ar/CH4/H2 plasma jets  

NASA Astrophysics Data System (ADS)

The effects of CH4 concentration (0.5-5%) on the growth mechanisms, nanostructures, and optically transparent properties of ultrananocrystalline diamond (UNCD) films grown from focused microwave Ar/CH4/H2 (argon-rich) plasma jets were systematically studied. The research results indicated that the grain size and surface roughness of the diamond films increased with increasing CH4 concentration in the plasma jet, however, the nondiamond contents in films would not be correspondingly decreased resulting from the dispersed diamond nanocrystallites in the films synthesized at higher CH4 concentration. The reason is due to that the relative emission intensity ratios of the C2/H? and the CH/C2 in the plasma jets were increased and decreased with increasing CH4 concentration, respectively, to lower the etching of nondiamond phase and the renucleation of diamond during synthesis. The studies of transmission electron microscopy demonstrated that, while the CH4 introduction of 1% into the plasma jet produced the UNCD films with a spherical geometry (4-8 nm) and the CH4 introduction of 5% into the plasma jet led to the elongated (˜90 nm in length and ˜35 nm in width) grains in the nanocrystalline diamond (NCD) films with a dendrite-like geometry. The transmittance of diamond films was decreased gradually by films transition from UNCD to NCD, resulting from the enhanced surface roughness and nondiamond contents in films to concurrently increase the light scattering and absorption during photon transmission.

Liao, Wen-Hsiang; Lin, Chii-Ruey; Wei, Da-Hua

2013-04-01

213

A comparison of mechanical properties of three MEMS materials - silicon carbide, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon (Ta-C)  

SciTech Connect

Many MEMS devices are based on polysilicon because of the current availability of surface micromachining technology. However, polysilicon is not the best choice for devices where extensive sliding and/or thermal fields are applied due to its chemical, mechanical and tribological properties. In this work, we investigated the mechanical properties of three new materials for MEMS/NEMS devices: silicon carbide (SiC) from Case Western Reserve University (CWRU), ultrananocrystalline diamond (UNCD) from Argonne National Laboratory (ANL), and hydrogen-free tetrahedral amorphous carbon (ta-C) from Sandia National Laboratories (SNL). Young's modulus, characteristic strength, fracture toughness, and theoretical strength were measured for these three materials using only one testing methodology - the Membrane Deflection Experiment (MDE) developed at Northwestern University. The measured values of Young's modulus were 430GPa, 960GPa, and 800GPa for SiC, UNCD, and ta-C, repectively. Fracture toughness measurments resulted in values of 3.2, 4.5, and 6.2 MPa x m{sup 1/2}, respectively. The strengths were found to follow a Weibull distribution but their scaling was found to be controlled by different specimen size parameters. Therefore, a cross comparison of the strengths is not fully meaningful. We instead propose to compare their theoretical strengths as determined by employing Novozhilov fracture criterion. The estimated theoretical strength for SiC is 10.6GPa at a characteristic length of 58nm, for UNCD is 18.6GPa at a characteristic length of 37nm, and for ta-C is 25.4GPa at a characteristic length of 38nm. The techniques used to obtained these results as well as microscopic fractographic analyses are summarized in the article. We also highlight the importance of characterizing mechanical properties of MEMS materials by means of only one simple and accurate experimental technique.

Carlisle, John A. (Argonne National Laboratory, Argonne, IL); Moldovan, N. (Northwestern University, Evanston, IL); Xiao, Xingcheng (Argonne National Laboratory, Argonne, IL); Zorman, C. A. (Case Western Reserve University, Cleveland, OH); Mancini, D. C. (Argonne National Laboratory, Argonne, IL); Peng, B. (Northwestern University, Evanston, IL); Espinosa, H. D. (Northwestern University, Evanston, IL); Friedmann, Thomas Aquinas; Auciello, Orlando, (Argonne National Laboratory, Argonne, IL)

2004-06-01

214

Ultrananocrystalline diamond film deposition by direct-current plasma assisted chemical vapor deposition using hydrogen-rich precursor gas in the absence of the positive column  

NASA Astrophysics Data System (ADS)

We have investigated the ultrananocrystalline diamond (UNCD) deposition by direct-current plasma assisted chemical vapor deposition on 4 in. Si wafer using CH4-H2 as well as CH4-Ar gas chemistry containing additive nitrogen. CH4/N2/H2 (5%/0.5%/94.5%) and CH4/N2/H2/Ar (0.5%/5%/6%/88.5%) gas mixtures were compared as the precursor gas. Molybdenum and tungsten were compared as cathode material. Discharge voltage and current were 480 V/45 A and 320 V/60 A, for respective gas chemistry. Chamber pressure and substrate temperature were 110-150 Torr and 750-850 °C, respectively. The film was characterized by near edge x-ray absorption fine structure spectroscopy, x-ray diffraction, high-resolution transmission electron microscope, electron energy loss spectroscopy, and high-resolution scanning electron microscope. We have demonstrated that (1) elimination of the positive column, by adopting very small interelectrode distance, gave some important and beneficial effects; (2) the plasma stability and impurity incorporation was sensitive to the cathode material and the precursor gas; (3) using the conventional CH4/H2 precursor gas and tungsten cathode, the mirror-smooth 4 in. UNCD film of excellent phase-purity and grain size below 10 nm could be deposited even in the absence of the positive column. The high electric field in the unusually narrow interelectrode space and the consequent high electron kinetic energy, in conjunction with the unusually high electron current thereof, directed to the substrate, i.e., the anode, was proposed to be the source of the grain refinement to achieve UNCD at such high chamber pressure around 110-150 Torr, in the absence of the usual ion bombardment assistance.

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

2011-01-01

215

TOPICAL REVIEW: Materials science and fabrication processes for a new MEMS technology based on ultrananocrystalline diamond thin films  

Microsoft Academic Search

Most MEMS devices are currently based on silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties which makes it difficult to produce high performance Si based MEMS devices that could work reliably, particularly in harsh environments; diamond, as a superhard material with high mechanical strength, exceptional chemical inertness, outstanding thermal stability and superior

Orlando Auciello; James Birrell; John A. Carlisle; Jennifer E. Gerbi; Xingcheng Xiao; Bei Peng; Horacio D. Espinosa

2004-01-01

216

Near-Edge X-ray Absorption Fine-Structure Spectroscopic Study on Nitrogen-Doped Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Pulsed Laser Deposition  

NASA Astrophysics Data System (ADS)

Nitrogen-doped ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films, which possessed n-type conduction with enhanced electrical conductivity, were prepared by pulsed laser deposition. The film doped with a nitrogen content of 7.9 at. % possessed enhanced electrical conductivity of 18 ?-1\\cdotcm-1 at 300 K. The near-edge X-ray absorption fine-structure (NEXAFS) measurement indicated the appearance of additional peaks due to ?* C=N, ?* C=N, and ?* C--N bonds compared with the spectra of undoped films. The sp2 bonding fraction estimated from the NEXAFS spectra increased with the nitrogen content. The enhanced electrical conductivity is probably due to the formation of additional ?* and ?* states and the enhancement in the sp2 bonding fraction.

Al-Riyami, Sausan; Ohmagari, Shinya; Yoshitake, Tsuyoshi

2011-08-01

217

Optical spectroscopy of the surface of nanoporous diamond films  

NASA Astrophysics Data System (ADS)

We have studied the IR absorption spectra of samples of porous ultrananocrystalline diamond (UNC diamond) obtained by selective etching of the sp 2 phase in UNC diamond films. We show that the surface of porous UNC diamond is polyfunctional. We have studied the behavior of surface hydride, carbonyl, carboxyl, and hydroxyl groups as a function of annealing temperature in air and the time kept under normal conditions for UNC diamond films previously oxidized at 430°C-450°C. In the range from a few minutes to a few months, we studied the kinetics for establishment of the steady state for the functional adsorbed layer on the diamond surface under normal conditions. The observed growth in the intensity of the transmission bands due to hydride (CH x ) and other hydrogen-containing functional groups is explained by dissociation of water molecules on the surface of the UNC diamond films.

Khomich, A. V.; Kanzyuba, M. V.; Vlasov, I. I.; Ral'Chenko, V. G.; Gorbachuk, N. I.

2011-09-01

218

Progress toward atomic layer epitaxy of diamond using radical chemistry  

NASA Astrophysics Data System (ADS)

A method for atomic layer epitaxy (ALE) of diamond using radical reactants under medium vacuum conditions is being developed. Precursor molecules are injected into a stream of thermally-dissociated fluorine atoms, generating radicals in a chemically specific way. We have grown diamond particles at rates of approximately 0.1 micrometers/hr on polycrystalline copper and nickel wire substrates seeded by diamond particles from continuous flows of F/F2, H2, and C2H3 or CH4 at substrate temperatures of 500-600 C and reactor pressures between 10(exp-3) and 10(exp-1) Torr. Identification of diamond with submicron lateral resolution was made using electron microprobe x-ray fluorescence wavelength dispersive spectroscopy.

Gat, R.; Hukka, T. I.; Develyn, M. P.

1993-05-01

219

Thermal conduction in nonhomogeneous CVD diamond layers in electronic microstructures  

Microsoft Academic Search

Chemical-vapor-deposited diamond layers of thickness between 0.1 and 5 μm have the potential to improve conduction cooling in electronic microstructures. However, thermal conduction in these layers is strongly impeded by phonon scattering on defects, whose concentrations can be highly nonhomogeneous, and on layer boundaries. By assuming that defects are concentrated near grain boundaries, this work relates the internal phonon scattering

K. E. Goodson

1996-01-01

220

Application of N- and B-doped CVD diamond layers for cyclic voltammetry measurements  

Microsoft Academic Search

Conductive polycrystalline diamond layers prepared by the CVD process have received attention from electrochemists owing to such superior electrochemical properties as the wide potential window, the very low background current, the stability of chemical and physical properties.In this paper, the cyclic voltammetry application using N- and B-doped diamond electrodes was studied. Diamond layers, doped with boron and nitrogen, were synthesized

R. Torz-Piotrowska; A. Wrzyszczynski; K. Paprocki; E. Staryga

2009-01-01

221

Effects of initial crystal size of diamond powder on surface residual stress and morphology in polycrystalline diamond (PCD) layer  

Microsoft Academic Search

Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3–20 ?m by the Ni70Mn25Co5 alloy infiltration technique at high temperature and high pressure (HPHT). The surface residual stress of polycrystalline\\u000a diamond (PCD) layer was measured using micro-Raman spectroscopy with hydrostatic stress model and X-ray diffraction (XRD).\\u000a Measurements of the stress levels of PCDs show that the

Hongsheng Jia; Xiaopeng Jia; Yue Xu; Lianru Wan; Kaikai Jie; Hongan Ma

2011-01-01

222

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

223

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

224

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

225

Cyclic voltammetry measurements on boron- and nitrogen-doped diamond layers  

Microsoft Academic Search

Diamond layers with different amounts of boron and nitrogen were deposited on silicon substrates in a hot-filament CVD reactor. These layers are characterized by the simultaneous deposition of diamond and graphite. Electrochemical properties were measured in acid and basic solutions to gain knowledge about their potential application as electrodes for industrial wastewater treatment or for other fields of electrochemistry. While

I. Gerger; R. Haubner

2005-01-01

226

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  

Microsoft Academic Search

A recently installed synchrotron radiation near-edge X-ray absorption fine structure (NEXAFS) full field imaging electron\\u000a spectrometer was used to spatially resolve the chemical changes of both counterfaces from an ultra- nanocrystalline diamond\\u000a (UNCD) tribological contact. A silicon flat and Si3N4 sphere were both coated with UNCD, and employed to form two wear tracks on the flat in a linear reciprocating

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

2011-01-01

227

Note: Laser ablation technique for electrically contacting a buried implant layer in single crystal diamond  

SciTech Connect

The creation of thin, buried, and electrically conducting layers within an otherwise insulating diamond by annealed ion implantation damage is well known. Establishing facile electrical contact to the shallow buried layer has been an unmet challenge. We demonstrate a new method, based on laser micro-machining (laser ablation), to make reliable electrical contact to a buried implant layer in diamond. Comparison is made to focused ion beam milling.

Ray, M. P.; Baldwin, J. W.; Butler, J. E.; Pate, B. B. [U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Feygelson, T. I. [SAIC, 1220 12th St. SE, Washington, DC 20003 (United States)

2011-05-15

228

Method of forming fluorine-bearing diamond layer on substrates, including tool substrates  

DOEpatents

A method of forming a fluorine-bearing diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-bearing plasma or other gas are then contacted under temperature and pressure conditions effective to nucleate fluorine-bearing diamond on the substrate. A tool insert substrate is treated prior to the diamond nucleation and growth operation by etching both the metal matrix and the hard particles using suitable etchants.

Chang, R. P. H. (Glenview, IL); Grannen, Kevin J. (Evanston, IL)

2002-01-01

229

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\\cdot 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

230

Multimode photoacoustic method for the evaluation of mechanical properties of heteroepitaxial diamond layers  

Microsoft Academic Search

A multimode photoacoustic method was developed for evaluating acoustically thick anisotropic layers, using surface acoustic waves. Such layers support multiple acoustic modes. This complicates the reverse problem, but on the other hand, makes it possible to extract more materials properties. Several mechanical properties of a layer-substrate system, consisting of a 110 mum thick heteroepitaxial chemical vapor deposited diamond layer on

Zhonghua H. Shen; Alexey M. Lomonosov; Peter Hess; Martin Fischer; Stefan Gsell; Matthias Schreck

2010-01-01

231

Combined experimental and modeling studies of microwave activated CH{sub 4}/H{sub 2}/Ar plasmas for microcrystalline, nanocrystalline, and ultrananocrystalline diamond deposition  

SciTech Connect

A comprehensive study of microwave (MW) activated CH{sub 4}/H{sub 2}/Ar plasmas used for diamond chemical vapor deposition is reported, focusing particularly on the effects of gross variations in the H{sub 2}/Ar ratio in the input gas mixture (from H{sub 2}/Ar mole fraction ratios of > 10:1, through to {approx}1:99). Absolute column densities of C{sub 2}(a) and CH(X) radicals and of H(n = 2) atoms have been determined by cavity ringdown spectroscopy, as functions of height (z) above a substrate and of process conditions (CH{sub 4}, H{sub 2}, and Ar input mole fractions, total pressure, p, and input microwave power, P). Optical emission spectroscopy has also been used to explore the relative densities of electronically excited H atoms, and CH, C{sub 2}, and C{sub 3} radicals, as functions of these same process conditions. These experimental data are complemented by extensive 2D (r, z) modeling of the plasma chemistry, which provides a quantitative rationale for all of the experimental observations. Progressive replacement of H{sub 2} by Ar (at constant p and P) leads to an expanded plasma volume. Under H{sub 2}-rich conditions, > 90% of the input MW power is absorbed through rovibrational excitation of H{sub 2}. Reducing the H{sub 2} content (as in an Ar-rich plasma) leads to a reduction in the absorbed power density; the plasma necessarily expands in order to accommodate a given input power. The average power density in an Ar-rich plasma is much lower than that in an H{sub 2}-rich plasma operating at the same p and P. Progressive replacement of H{sub 2} by Ar is shown also to result in an increased electron temperature, an increased [H]/[H{sub 2}] number density ratio, but little change in the maximum gas temperature in the plasma core (which is consistently {approx}3000 K). Given the increased [H]/[H{sub 2}] ratio, the fast H-shifting (C{sub y}H{sub x} + H {r_reversible} C{sub y}H{sub x-1} + H{sub 2}; y = 1-3) reactions ensure that the core of Ar-rich plasma contains much higher relative abundances of ''product'' species like C atoms, and C{sub 2,} and C{sub 3} radicals. The effects of Ar dilution on the absorbed power dissipation pathways and the various species concentrations just above the growing diamond film are also investigated and discussed.

Richley, James C.; Fox, Oliver J. L.; Ashfold, Michael N. R. [School of Chemistry, University of Bristol, Bristol, BS8 1TS (United Kingdom); Mankelevich, Yuri A. [Skobel'tsyn Institute of Nuclear Physics, Moscow State University, Leninskie gory, Moscow, 119991 (Russian Federation)

2011-03-15

232

Combined experimental and modeling studies of microwave activated CH4/H2/Ar plasmas for microcrystalline, nanocrystalline, and ultrananocrystalline diamond deposition  

NASA Astrophysics Data System (ADS)

A comprehensive study of microwave (MW) activated CH4/H2/Ar plasmas used for diamond chemical vapor deposition is reported, focusing particularly on the effects of gross variations in the H2/Ar ratio in the input gas mixture (from H2/Ar mole fraction ratios of > 10:1, through to ~1:99). Absolute column densities of C2(a) and CH(X) radicals and of H(n = 2) atoms have been determined by cavity ringdown spectroscopy, as functions of height (z) above a substrate and of process conditions (CH4, H2, and Ar input mole fractions, total pressure, p, and input microwave power, P). Optical emission spectroscopy has also been used to explore the relative densities of electronically excited H atoms, and CH, C2, and C3 radicals, as functions of these same process conditions. These experimental data are complemented by extensive 2D (r, z) modeling of the plasma chemistry, which provides a quantitative rationale for all of the experimental observations. Progressive replacement of H2 by Ar (at constant p and P) leads to an expanded plasma volume. Under H2-rich conditions, > 90% of the input MW power is absorbed through rovibrational excitation of H2. Reducing the H2 content (as in an Ar-rich plasma) leads to a reduction in the absorbed power density; the plasma necessarily expands in order to accommodate a given input power. The average power density in an Ar-rich plasma is much lower than that in an H2-rich plasma operating at the same p and P. Progressive replacement of H2 by Ar is shown also to result in an increased electron temperature, an increased [H]/[H2] number density ratio, but little change in the maximum gas temperature in the plasma core (which is consistently ~3000 K). Given the increased [H]/[H2] ratio, the fast H-shifting (CyHx + H <--> CyHx-1 + H2; y = 1-3) reactions ensure that the core of Ar-rich plasma contains much higher relative abundances of ``product'' species like C atoms, and C2, and C3 radicals. The effects of Ar dilution on the absorbed power dissipation pathways and the various species concentrations just above the growing diamond film are also investigated and discussed.

Richley, James C.; Fox, Oliver J. L.; Ashfold, Michael N. R.; Mankelevich, Yuri A.

2011-03-01

233

Multimode photoacoustic method for the evaluation of mechanical properties of heteroepitaxial diamond layers  

NASA Astrophysics Data System (ADS)

A multimode photoacoustic method was developed for evaluating acoustically thick anisotropic layers, using surface acoustic waves. Such layers support multiple acoustic modes. This complicates the reverse problem, but on the other hand, makes it possible to extract more materials properties. Several mechanical properties of a layer-substrate system, consisting of a 110 ?m thick heteroepitaxial chemical vapor deposited diamond layer on Ir/YSZ (yttria-stabilized zirconia)/Si(001), were evaluated, based on two surface acoustic modes. A dispersive and a nondispersive mode measured in two different crystallographic directions were employed to evaluate the three elastic stiffness coefficients C11, C12, C44, and the mass density of the diamond layer. It is demonstrated that accurate elastic moduli can be determined without special sample preparation, employing the layered system as obtained from the heteroepitaxial diamond growth process.

Shen, Zhonghua H.; Lomonosov, Alexey M.; Hess, Peter; Fischer, Martin; Gsell, Stefan; Schreck, Matthias

2010-10-01

234

Growth and electrical characterisation of ?-doped boron layers on (111) diamond surfaces  

NASA Astrophysics Data System (ADS)

A plasma enhanced chemical vapor deposition protocol for the growth of ?-doping of boron in diamond is presented, using the (111) diamond plane as a substrate for diamond growth. AC Hall effect measurements have been performed on oxygen terminated ?-layers and desirable sheet carrier densities (~1013 cm-2) for field-effect transistor application are reported with mobilities in excess of what would expected for equivalent but thicker heavily boron-doped diamond films. Temperature-dependent impedance spectroscopy and secondary ion mass spectroscopy measurements show that the grown layers have metallic-like electrical properties with high cut-off frequencies and low thermal impedance activation energies with estimated boron concentrations of approximately 1020 cm-3.

Edgington, Robert; Sato, Syunsuke; Ishiyama, Yuichiro; Morris, Richard; Jackman, Richard B.; Kawarada, Hiroshi

2012-02-01

235

Fluorine-Based Mechanisms for Atomic-Layer-Epitaxial Growth on Diamond (110)  

NASA Astrophysics Data System (ADS)

Atomic-layer-epitaxy (ALE) processes for the growth of diamond are evaluated using ab initio molecular dynamics. It is shown that the Cl-based ALE cycle on diamond (111) is not advantageous, due to strong steric hindrances. New ALE processes are proposed and shown to be energetically favorable, self-limiting, and sterically unhindered. They exploit the large heat of formation and the small size of the HF molecule and are based on alternating exposure of the diamond (110) surface to hydrocarbons and fluorocarbons. Alternatively, H and F gases can be used in parts of the cycle.

Wensell, M. G.; Zhang, Z.; Bernholc, J.

1995-06-01

236

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

237

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

238

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

239

Integration of perovskite PZT thin films on diamond substrate without buffer layer  

NASA Astrophysics Data System (ADS)

Integration of lead zirconate titanate (PZT) thin film on diamond substrate offers a great deal of potential for the application of multifunctional devices under extreme conditions. However, fabrication of perovskite PZT thin films on diamond substrate without a buffer layer has not been realized to date. We report for the first time on the successful deposition of PZT thin film directly on a diamond substrate without any buffer layer using the pulsed-laser deposition technique. The perovskite phase was realized only under specific growth conditions. X-ray diffraction and Raman studies confirmed the perovskite phase. The ferroelectric behaviour of the deposited PZT thin film was confirmed using piezo response microscope phase image and ferroelectric hysteresis loop.

Chandran, Maneesh; Tiwari, Brajesh; Kumaran, C. R.; Samji, Sunil K.; Bhattacharya, S. S.; Ramachandra Rao, M. S.

2012-05-01

240

A route to diamond wafers by epitaxial deposition on silicon via iridium/yttria-stabilized zirconia buffer layers  

NASA Astrophysics Data System (ADS)

A multilayer structure is presented which allows the deposition of high-quality heteroepitaxial diamond films on silicon. After pulsed-laser deposition of a thin yttria-stabilized zirconia (YSZ) layer on silicon, iridium was deposited by e-beam evaporation. Subsequently, diamond nucleation and growth was performed in a chemical vapor deposition setup. The epitaxial orientation relationship measured by x-ray diffraction is diamond(001)[110]?Ir(001)[110]?YSZ(001) [110]?Si(001)[110]. The mosaicity of the diamond films is about an order of magnitude lower than for deposition directly on silicon without buffer layers and nearly reaches the values reported for single-crystal diamond on Ir/SrTiO3. In the effort towards single-crystal diamond wafers, the present solution offers advantages over alternative growth substrates like large-area oxide single crystals due to the low thermal expansion mismatch.

Gsell, S.; Bauer, T.; Goldfuß, J.; Schreck, M.; Stritzker, B.

2004-05-01

241

Diamond-like carbon as a buffer layer in polymeric electroluminescent device  

Microsoft Academic Search

Diamond-like carbon (DLC) layer was deposited by the Cs+ ion sputtered negative ion deposition technique between hole transport layer and indium tin oxide (ITO) anode for polymeric electroluminescent device. An acidic poly(styrene sulfonate)-doped poly(3,4-ethylene dioxythiophene):poly-(styrenesulphonic acid) (PEDOT:PSS) solution acting as a hole transporting material etches the ITO surface and the PEDOT:PSS\\/ITO interface is not stable. X-ray photoelectron spectroscopy and Rutherford

Sang Hun Choi; Soon Moon Jeong; Won Hoe Koo; Sung Jin Jo; Hong Koo Baik; Se-Jong Lee; Kie Moon Song; Dong Won Han

2005-01-01

242

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

2012-02-15

243

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

244

Analysis of diamond surface channel field-effect transistors with AlN passivation layers  

NASA Astrophysics Data System (ADS)

Diamond surface channel field effect transistors were passivated with thin AlN layers grown by metal-organic chemical vapor deposition in order to improve the chemical stability of the surface-near p-type channel. Electrical characterization showed that the surface-near conductivity in the diamond is preserved during AlN overgrowth if the process temperature does not exceed 800 °C. However, the sheet carrier density is decreased by a factor of about 5 compared to the unpassivated hydrogen-terminated surface. A combination of TEM and XPS analysis showed that this effect is not induced by a partial modification of the surface termination or by a polarization of the AlN passivation. The preserved, but reduced surface-near conductivity in the diamond can however be explained by a hydrogen double bond between the diamond and the AlN film. Field-effect transistor structures fabricated on the passivated diamond substrates showed stable operation up drain-source voltages to -70 V and might therefore be promising candidates for future high-voltage applications.

Pietzka, C.; Scharpf, J.; Fikry, M.; Heinz, D.; Forghani, K.; Meisch, T.; Diemant, Th.; Behm, R. J.; Bernhard, J.; Biskupek, J.; Kaiser, U.; Scholz, F.; Kohn, E.

2013-09-01

245

DNA-modified nanocrystalline diamond thin-films as stable, biologically active substrates.  

SciTech Connect

Diamond, because of its electrical and chemical properties, may be a suitable material for integrated sensing and signal processing. But methods to control chemical or biological modifications on diamond surfaces have not been established. Here, we show that nanocrystalline diamond thin-films covalently modified with DNA oligonucleotides provide an extremely stable, highly selective platform in subsequent surface hybridization processes. We used a photochemical modification scheme to chemically modify clean, H-terminated nanocrystalline diamond surfaces grown on silicon substrates, producing a homogeneous layer of amine groups that serve as sites for DNA attachment. After linking DNA to the amine groups, hybridization reactions with fluorescently tagged complementary and non-complementary oligonucleotides showed no detectable non-specific adsorption, with extremely good selectivity between matched and mismatched sequences. Comparison of DNA-modified ultrananocrystalline diamond films with other commonly used surfaces for biological modification, such as gold, silicon, glass and glassy carbon, showed that diamond is unique in its ability to achieve very high stability and sensitivity while also being compatible with microelectronics processing technologies. These results suggest that diamond thin-films may be a nearly deal substrate for integration of microelectronics with biological modification and sensing.

Yang, W.; Auciello, O.; Butler, J. E.; Cai, W.; Carlisle, J. A.; Gerbi, J. E.; Gruen, D. M.; Knickerbocker, T.; Lasseter, T. L.; Russell, J. N., Jr.; Smith, L. M.; Hamers, R. J.; Materials Science Division; Univ. of Wisconsin-Madison; Naval Research Lab.

2002-12-01

246

Electrochemical characterization of the nanoporous honeycomb diamond electrode as an electrical double-layer capacitor  

Microsoft Academic Search

Electrochemical properties of nanoporous honeycomb diamond electrodes in an aqueous electrolyte were investigated. Highly ordered honeycomb diamond structures were fabricated by etching the microwave plasma-deposited diamond films using an oxygen plasma. The diamond honeycomb exhibited a wide electrochemical potential window (ca. 2.5 V), similar to the unetched diamond film. From impedance measurements, the capacitance of the diamond honeycomb film was

K. Honda; Tata N. Rao; D. A. Tryk; A. Fujishima; M. Watanabe; K. Yasui; H. Masuda

2000-01-01

247

Tuneable anisotropic transport in nitrogen-doped nanocrystalline diamond films: Evidence of a graphite-diamond hybrid superlattice  

NASA Astrophysics Data System (ADS)

We show strong evidence of superlattice-like carbon layered structures in heavily nitrogen-doped ultrananocrystalline diamond (UNCD) films through the experimental demonstration of temperature-dependent anisotropic diffusive transport. The superlattice periodicity, in the range of several nanometers, is derived from the analysis of both magneto-resistance and the temperature-dependent conductivity based on the generalized diffusive Fermi surface model. The effect of quasi-two-dimensionality on the magneto-transport of these films yields a weak temperature dependence of the electron dephasing length. These results explain a reasonably strong coupling between the conducting carbon layers separated by the insulating nanodiamond grains producing the anisotropic transport in UNCD films controlled by the level of nitrogen incorporation.

Churochkin, Dmitry; Bhattacharyya, Somnath

2012-12-01

248

Nucleation enhancement of diamond using diamond-like carbon film synthesized from polymer as an intermediate layer  

Microsoft Academic Search

Using a conventional hot-filament chemical vapor deposition system, diamond crystals and films were deposited on diamond-like carbon (DLC) films which were synthesized from a [C6H5C]n polymer on silicon substrates under a temperature of 1000 °C in an argon atmosphere. The nucleation density of the diamond on DLC-Si substrates was estimated to be about 108 to 1010 cm?2, equivalent to or

Z. Sun; Z. Zheng; Y. Sun; Q. Yang; Y. He

1995-01-01

249

Electrical conduction of high-conductivity layers near the surfaces in hydrogenated homoepitaxial diamond films  

NASA Astrophysics Data System (ADS)

In order to clarify the origin of high-conductivity layers (HCL) near the surfaces of hydrogenated diamond films, we have studied the relationship between HCL and surface structure in B-doped homoepitaxial (001) diamond films. Samples annealed in nitrogen environment at various temperatures have been characterized by Hall-effect measurements and reflection high-energy electron diffraction. It was found that HCL disappeared in the films annealed at a temperature higher than 350°C, but the (001)-2×1 surface-structures observed in hydrogenated films remained at 350°C. This indicates that HCL is not related directly with the (001)-2×1 surface-structure. The origin of HCL will be discussed on the basis of the present results.

Yamanaka, S.; Takeuchi, D.; Watanabe, H.; Okushi, H.; Kajimura, K.

2000-06-01

250

Surface Evaluation of Fluorinated Diamond-Like Carbon Thin Film as an Antisticking Layer of Nanoimprint Mold  

Microsoft Academic Search

The surface property of fluorinated diamond-like carbon (F-DLC) thin film, which is expected to be a new antisticking layer of nanoimprint mold, was evaluated with reference to the commercial diamond-like carbon (DLC) thin film formed by radio-frequency (RF) plasma chemical vapor deposition (CVD) and the fluorinated self-assembled monolayer (SAM). From the measurement of X-ray photoelectron spectrum (XPS), the surface of

Noriko Yamada; Ken-ichiro Nakamatsu; Kazuhiro Kanda; Yuichi Haruyama; Shinji Matsui

2007-01-01

251

Fluorinated Diamond-Like Carbon Coating as Antisticking Layer on Nanoimprint Mold  

NASA Astrophysics Data System (ADS)

Fluorinated diamond-like carbon (F-DLC) has recently been applied as an antisticking layer on nanoimprint molds for semipermanent use, replacing the self-assembled monolayer currently used. An SiO2/Si mold was successfully coated with an F-DLC thin layer by chemical vapor deposition (CVD). The measured water contact angle of the F-DLC surface was 103°, which is 30° higher than that of the DLC surface. This value indicates the adequacy of F-DLC as an antisticking layer. Moreover, an F-DLC film had a high hardness of 24 GPa, similar to that of a DLC film (26 GPa). AZ resist patterns of 150 nm linewidth and 350 nm pitch were successfully obtained by thermal nanoimprinting using an F-DLC-coated mold. Finally, after repeating the imprinting for more than 100 times, the initial water contact angle of 103° for the surface of the F-DLC-coated mold was maintained.

Nakamatsu, Ken-ichiro; Yamada, Noriko; Kanda, Kazuhiro; Haruyama, Yuichi; Matsui, Shinji

2006-09-01

252

Diamonds from the iridium-rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico  

NASA Astrophysics Data System (ADS)

Diamonds, up to 30 ?m in size, were found in the iridium-rich layer from the K-T boundary site at Arroyo El Mimbral and the spherule bed from Arroyo El Peñon, northeastern Mexico. Stepped heating experiments indicate two or more isotopically distinct diamond components with carbon isotopic compositions characteristic of a mixture of carbon sources. The diamonds' crystal form is cubic—not the hexagonal polymorph of diamond, lonsdaleite, which has been used previously to infer formation due to shock transformation of graphite. The size, crystallography, and mineralogic associations of K-T diamonds are similar to those of impact-produced diamonds from the Ries crater in Germany where both shock transformation of graphite and a mode of formation by condensation from a vapor plume have been inferred. The discovery of impact-produced diamonds in association with high Ir contents for these sediments supports their impact origin, K-T age, and the inference that their source was from the buried impact crater of Chicxulub on the Yucatan peninsula, Mexico.

Hough, R. M.; Gilmour, I.; Pillinger, C. T.; Langenhorst, F.; Montanari, A.

1997-11-01

253

Calibration of an isotopically enriched carbon-13 layer pressure sensor to 156 GPa in a diamond anvil cell  

SciTech Connect

An isotopically enriched {sup 13}C homoepitaxial diamond layer of 6{+-}1 {mu}m thickness was grown on top of a brilliant cut diamond anvil by a microwave plasma chemical vapor deposition process for application as a pressure sensor. This isotopically enriched diamond tip was then used in conjunction with a natural isotopic abundance diamond anvil to generate high pressure on the sample. We provide a calibration for the {sup 13}C Raman mode of this extremely thin epitaxial layer to 156 GPa using ruby fluorescence and the equation of state of copper as secondary pressure standards. The nonlinear calibration of the {sup 13}C Raman mode pressure sensor is compared with similar calibrations of {sup 12}C Raman edge and a good agreement is obtained. The Raman signal from the {sup 13}C epitaxial layer remained a distinct singlet to 156 GPa, and pressure calibration is independent of sample mechanical strength or the diamond anvil geometry. The use of even thinner layer would allow calibration further into ultrahigh pressure regime where the use of other optical sensors has proven to be difficult.

Qiu Wei; Baker, Paul A.; Velisavljevic, Nenad; Vohra, Yogesh K.; Weir, Samuel T. [Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, Alabama 35294-1170 (United States); Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94550 (United States)

2006-03-15

254

Calibration of an isotopically enriched carbon-13 layer pressure sensor to 156 GPa in a diamond anvil cell  

SciTech Connect

An isotopically enriched {sup 13}C homoepitaxial diamond layer of 6{+-}1 {mu}m thickness was grown on top of a brilliant cut diamond anvil by a microwave plasma chemical vapor deposition process for application as a pressure sensor. This isotopically enriched diamond tip was then used in conjunction with a natural isotopic abundance diamond anvil to generate high pressure on the sample. We provide a calibration for the {sup 13}C Raman mode of this extremely thin epitaxial layer to 156 GPa using ruby fluorescence and the equation of state of copper as secondary pressure standards. The nonlinear calibration of the {sup 13}C Raman mode pressure sensor is compared with similar calibrations of {sup 12}C Raman edge and a good agreement is obtained. The Raman signal from the {sup 13}C epitaxial layer remained a distinct singlet to 156 GPa, and pressure calibration is independent of sample mechanical strength or the diamond anvil geometry. The use of even thinner layer would allow calibration further into ultrahigh pressure regime where the use of other optical sensors has proven to be difficult.

Qiu,W.; Baker, P.; Velisavljevic, N.; Vohra, Y.; Weir, S.

2006-01-01

255

Hydrogen-free diamond-like carbon deposited by a layer-by-layer technique using PECVD  

SciTech Connect

The authors developed a hydrogen-free diamond like carbon (DLC) film by a novel deposition technique of a layer-by-layer technique using plasma enhanced chemical vapor deposition (PECVD) in which a repeated deposition of a thin DLC layer and subsequently CF{sub 4} plasma treatment on its surface have been carried out. The electrical, optical and structural properties of the DLC films deposited depend on the CF{sub 4} plasma exposure time. The hydrogen content is less than 1 at % when the CF{sub 4} plasma exposure time is 140s. Its emission current is much higher and stability is much improved compared with conventional DLC.N-type, hydrogen-free DLC could be obtained by N ion doping or by N{sub 2} gas-phase doping in the CH{sub 4} plasma. The optimum [N{sub 2}]/[CH{sub 4}] flow rate ratio was found to be 9% for the efficient electron emission, at which the onset-field was 7.2 V/{micro}m. The nitrogen gas-phase doped hydrogen-free DLC coating on Mo tip field emitter arrays (FEAs) increased the electron emission current from 160{micro}A to 1.52 mA and improved the stability in electron emission current.

Jang, J.; Chung, S.J.

2000-01-30

256

Low temperature boron doped diamond  

NASA Astrophysics Data System (ADS)

Low temperature boron doped diamond (LT-BDD) film deposited under 600 °C (460 °C minimum) has been reported. Study reveals that the deposition temperature and boron dopant cause nanocrystalline diamond (NCD) instead of ultrananocrystalline diamond (UNCD®). Unlike conventional NCD, LT-BDD has faster renucleation rate, which ensures a low surface roughness (approximately 10 nm at 0.6 ?m thickness). The overall characteristics of LT-BDD are mixed with the characteristics of conventional NCD and UNCD. Raman spectrum and electrochemical characterization prove that the quality of LT-BDD is similar to those grown under 650-900 °C. LT-BDD enables diamond applications on microelectromechanical systems, bio- and optical technologies.

Zeng, Hongjun; Arumugam, Prabhu U.; Siddiqui, Shabnam; Carlisle, John A.

2013-06-01

257

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

258

Cell adhesion properties on photochemically functionalized diamond.  

PubMed

The biocompatibility of diamond was investigated with a view toward correlating surface chemistry and topography with cellular adhesion and growth. The adhesion properties of normal human dermal fibroblast (NHDF) cells on microcrystalline and ultrananocrystalline diamond (UNCD) surfaces were measured using atomic force microscopy. Cell adhesion forces increased by several times on the hydrogenated diamond surfaces after UV irradiation of the surfaces in air or after functionalization with undecylenic acid. A direct correlation between initial cell adhesion forces and the subsequent cell growth was observed. Cell adhesion forces were observed to be strongest on UV-treated UNCD, and cell growth experiments showed that UNCD was intrinsically more biocompatible than microcrystalline diamond surfaces. The surface carboxylic acid groups on the functionalized diamond surface provide tethering sites for laminin to support the growth of neuron cells. Finally, using capillary injection, a surface gradient of polyethylene glycol could be assembled on top of the diamond surface for the construction of a cell gradient. PMID:17407337

Chong, Kwok Feng; Loh, Kian Ping; Vedula, S R K; Lim, Chwee Teck; Sternschulte, Hadwig; Steinmüller, Doris; Sheu, Fwu-Shan; Zhong, Yu Lin

2007-04-04

259

Nitrogenated nanocrystalline diamond films: Thermal and optical properties  

Microsoft Academic Search

Ultrananocrystalline diamond films have been grown by microwave plasma CVD using CH4\\/H2\\/Ar mixtures with N2 added in plasma in amounts up to 25%. The films were characterized with AFM, Raman, XRD, and UV–IR optical absorption spectroscopy mainly focusing on optical and thermal properties. In comparison with polycrystalline CVD diamond the UNCD are very smooth (Ra<10 nm), have low thermal conductivity (?0.10 W\\/cm

V. Ralchenko; S. Pimenov; V. Konov; A. Khomich; A. Saveliev; A. Popovich; I. Vlasov; E. Zavedeev; A. Bozhko; E. Loubnin; R. Khmelnitskii

2007-01-01

260

Presence of all Three Allotropes of Impact-Diamonds in the Younger Dryas Onset Layer (YDB) Across N America and NW Europe  

NASA Astrophysics Data System (ADS)

We report the discovery of all three diamond allotropes (cubic diamond, lonsdaleite, and n-diamond) in an extraterrestrial (ET) impact layer (the YDB), dating to the Younger Dryas onset at 12.9 ka. YDB diamonds are distributed broadly across N America and NW Europe at 15 sites spanning 9,000 km or 23 percent of Earth's circumference. N-diamonds and lonsdaleite, or hexagonal diamond, do not co-occur with terrestrial diamonds, but are found in meteorites. Lonsdaleite is found on Earth only in association with known ET impacts, and thus, is a definitive impact indicator. The diamonds were identified by transmission electron microscopy (TEM) using selected area diffraction (SAED), which display reflections corresponding to the following lattice planar spacings definitive of diamond: (1) cubic: 2.06, 1.26, 1.07, and 0.89 A; (2) lonsdaleite: 2.184, 1.261, 1.092, and 0.826 A; and (3) n-diamond: 2.06, 1.26, 1.07, and 0.89 A, plus "forbidden" reflections of 1.78, 1.04, and 0.796 A. Nanodiamonds are rounded to highly angular, and range in size from 1 to 1700 nm with most between 1 and 50 nm. Concentrations are up to 3700 ppb, equaling more than 1 billion diamonds per cm3 of sediment (comparable to K/T levels of 3600 ppb). No diamonds were detected above or below the YDB layer at any site tested. These diamonds could not have formed from volcanic activity, because they combust at temperatures above 500° C in the presence of atmospheric levels of oxygen, and micrometeoritic diamonds are similarly destroyed. Also, the diamonds could not have accumulated from the constant rain of micrometeoritic debris, because multi-billions occur in YDB layer samples, but yet none have been found in non-YDB strata dating from 55,000 RCYBP to present. YDB diamonds are associated with abundance peaks in magnetic spherules, carbon spherules, soot, and iridium, which can peak in impact layers of known ET events, such as the K/T and the 1908 airburst at Tunguska, Siberia. Furthermore, a high proportion of the nanodiamonds are found deeply embedded within spherical particles of melted plant resins, a fact inexplicable by any normal terrestrial process. Altogether, this evidence strongly suggests that the widespread and abundant nanodiamonds constrained to the thin YDB layer resulted from a major ET impact/airburst at 12.9 ka.

West, A.; Kennett, J. P.; Kennett, D. J.; Que Hee, S. S.; Wolbach, W. S.; Stich, A.; Bunch, T. E.; Wittke, J. H.; Mercer, C.; Sellers, M.; Culleton, B. J.; Erlandson, J. M.; Johnson, J. R.; Stafford, T. W.; Weaver, J. C.; West, G.

2008-12-01

261

Diamond-Like-Carbon LC-Alignment Layers for Application in LCOS Microdisplays  

SciTech Connect

To improve the lifetime and yield of LCOS microdisplays, non-contact LC alignment techniques using inorganic materials are under investigation. This report focuses on oblique ion-beam treatment of diamond-like carbon (DLC) layers, and in particular on the influence of the ion dose on the LC alignment on DLC, keeping the ion-beam angle (40 degrees) and ion-beam energy (170 eV) the same. LC alignment on ion-milled DLC layers is uniform if the ion dose is between 3.8 x 10{sup -4} C/cm{sup 2} and 5.5x10{sup -3} C/cm{sup 2}. Above and below this ion dose range, non-uniform alignment is observed. NEXAFS experiments show that this is caused by lack of molecular anisotropy on the surface of the ion-milled DLC layers. By varying the ion dose between 3.8 x 10{sup -4} C/cm{sup 2} and 5.5 x 10{sup -3} C/cm{sup 2}, LC molecules have an average pre-tilt between 3 and 5 degrees, which is within the desired range for application in LCOS microdisplays. The lifetime of the LCOS microdisplays with ion-milled DLC for projection-TV application is, however, shorter than the lifetime of microdisplays with PI layers. Ion milling probably creates a reactive surface that is unstable under the high light fluxes used in projection TVs. A solution for this problem could be chemical passivation of the ion-milled alignment layers. Initial experiments with passivation of ion-milled PI resulted in an increase in lifetime, but the lifetime after passivation was still lower than the lifetime of rubbed PI layers (factor 0.7). Nevertheless, ion-milling of DLC or PI can be a good alternative LC alignment technique in other LCD applications. LC-alignment layers based on inorganic layers such as obliquely deposited SiO{sub 2} films would be a better option for application in LCOS microdisplays due to their higher light stability.

Bol,A.; Dvorak, J.; Arena, D.

2005-01-01

262

Simulations of chemical vapor deposition diamond film growth using a kinetic Monte Carlo model and two-dimensional models of microwave plasma and hot filament chemical vapor deposition reactors  

Microsoft Academic Search

A one-dimensional kinetic Monte Carlo (KMC) model has been developed to simulate the chemical vapor deposition of a diamond (100) surface under conditions used to grow single-crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films. The model considers adsorption, etching\\/desorption, lattice incorporation and surface migration but not defect formation or renucleation processes. Two methods have

P. W. May; J. N. Harvey; N. L. Allan; J. C. Richley; Yu. A. Mankelevich

2010-01-01

263

All Diamond Self-Aligned Thin Film Transistor.  

National Technical Information Service (NTIS)

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 ...

J. Gerbi

2005-01-01

264

Electrochemical characterization of the nanoporous honeycomb diamond electrode as an electrical double-layer capacitor  

SciTech Connect

Electrochemical properties of nanoporous honeycomb diamond electrodes in an aqueous electrolyte were investigated. Highly ordered honeycomb diamond structures were fabricated by etching the microwave plasma-deposited diamond films using an oxygen plasma. The diamond honeycomb exhibited a wide electrochemical potential window (ca. 2.5 V), similar to the unetched diamond film. From impedance measurements, the capacitance of the diamond honeycomb film was found to be 1.97 x 10{sup {minus}3} F/cm (geometric area), which is ca. 200 times greater than that for the unetched, as-deposited surface. The results obtained with galvanostatic measurements were consistent with this value. The formation of the highly ordered porous structure, together with surface oxidation, was found to be responsible for the observed enhancement in the capacitance. The transmission line model for cylindrically porous electrodes was successfully applied to the present honeycomb structure. Based on an estimation of the capacitance of a hypothetical through-hole diamond membrane, the specific capacitance is ca. 16 F/g, which is within an order of magnitude of the range for activated carbon capacitors (100 to 400 F/g).

Honda, K.; Rao, T.N.; Tryk, D.A.; Fujishima, A.; Watanabe, M.; Yasui, K.; Masuda, H.

2000-02-01

265

Polymerization and diamond formation from melting methane and their implications in ice layer of giant planets  

Microsoft Academic Search

High-pressure and high-temperature experiments of solid methane were performed using a laser-heated diamond anvil cell. X-ray diffractometry and Raman spectroscopy revealed the melting conditions to be above approximately 1100K in a wide pressure range of 10–80GPa. Above 1100K, polymerizations occurred to produce ethane molecules and further polymerized hydrocarbons. Above 3000K, diamond was produced. These changes proceeded depending on temperature rather

Hisako Hirai; Keisuke Konagai; Taro Kawamura; Yoshitaka Yamamoto; Takehiko Yagi

2009-01-01

266

Layered mantle structure beneath the western Guyana Shield, Venezuela: Evidence from diamonds and xenocrysts in Guaniamo kimberlites  

NASA Astrophysics Data System (ADS)

Mantle xenoliths and xenocrysts from Guaniamo, Venezuela kimberlites record equilibration conditions corresponding to a limited range of sampling in the lithosphere (100-150 km). Within this small range, however, compositions vary considerably, but regularly, defining a strongly layered mantle sequence. Major and trace element compositions suggest the following lithologic sequence: highly depleted lherzolite from 100 to 115 km, mixed ultra-depleted harzburgite and lherzolite from 115 to 120 km, relatively fertile lherzolite from 120 to 135 km, and mixed depleted harzburgite and relatively fertile lherzolite from 135 to 150 km. Based on comparison with well-documented mantle peridotites and xenocrysts from elsewhere, we conclude that the Meso-proterozoic Cuchivero Province (host to the Guaniamo kimberlites) is underlain by depleted and ultra-depleted shallow Archean mantle that was underplated, and uplifted, by Proterozoic subduction, perhaps more than once. These Proterozoic subduction events introduced less-depleted oceanic lithosphere beneath the Archean section, which remains there and is the source of the abundant Guaniamo eclogite-suite diamonds that have ocean-floor geochemical signatures. Although diamond-indicative low-Ca Cr-pyrope garnets are abundant, they are derived primarily from the shallow depleted layer within the field of graphite stability, and the rare peridotite-suite diamonds are either metastably preserved at these shallow depths, or were derived from the small amount of depleted lithosphere sampled by these kimberlites that remains within the diamond stability field (the mixture of Archean and Proterozoic mantle in the depth range 135-150 km).

Schulze, Daniel J.; Canil, Dante; Channer, Dominic M. DeR.; Kaminsky, Felix V.

2006-01-01

267

Thermally stable diamond brazing  

DOEpatents

A cutting element and a method for forming a cutting element is described and shown. The cutting element includes a substrate, a TSP diamond layer, a metal interlayer between the substrate and the diamond layer, and a braze joint securing the diamond layer to the substrate. The thickness of the metal interlayer is determined according to a formula. The formula takes into account the thickness and modulus of elasticity of the metal interlayer and the thickness of the TSP diamond. This prevents the use of a too thin or too thick metal interlayer. A metal interlayer that is too thin is not capable of absorbing enough energy to prevent the TSP diamond from fracturing. A metal interlayer that is too thick may allow the TSP diamond to fracture by reason of bending stress. A coating may be provided between the TSP diamond layer and the metal interlayer. This coating serves as a thermal barrier and to control residual thermal stress.

Radtke, Robert P. (Kingwood, TX)

2009-02-10

268

A stable suspension of single ultrananocrystalline diamond particles  

Microsoft Academic Search

As the result of successful disintegration of tight aggregates in detonation nanodiamond by stirred-media milling with microbeads, stable colloid of nanodiamond particles with a mean core size of 4 nm is obtained for the first time, but the colloid is colored deep black. X-ray diffraction, Raman scattering, HRTEM, UV–vis absorption spectra and viscosity data were used to characterize the colloid.

E. D. Eidelman; V. I. Siklitsky; L. V. Sharonova; M. A. Yagovkina; M. Takahashi; M. Inakuma; M. Ozawa; E. ?sawa

2005-01-01

269

Paramagnetic defects and exchange coupled spins in pristine ultrananocrystalline diamonds  

Microsoft Academic Search

Electron paramagnetic resonance (EPR) and magnetic susceptibility measurements were done on nanodiamond samples fabricated by the detonation method and purified by acids. Comprehensive acid treatment leads to the reduction of EPR signals of magnetic impurities and revealing two weak and narrow EPR lines with g1=4.26, ?Hpp=2.9 mT and g2=4.00, ?Hpp=1.4 mT at T=4 K, separated by the distance of 10.4 mT. The origin of

V. Yu. Osipov; A. I. Shames; T. Enoki; K. Takai; M. V. Baidakova

2007-01-01

270

N-type droping of nanocrystalline diamond films with nitrogen and electrodes made therefrom  

SciTech Connect

An electrically conducting n-type ultrananocrystalline diamond (UNCD) having no less than 10.sup.19 atoms/cm.sup.3 of nitrogen is disclosed. A method of making the n-doped UNCD. A method for predictably controlling the conductivity is also disclosed.

Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (late of Naperville, IL); Auciello, Orlando H. (Bolingbrook, IL); Carlisle, John A. (Plainfield, IL)

2004-09-21

271

Density Functional Based Tight Binding Study of C2 and CN Deposition on (100) Diamond Surface.  

National Technical Information Service (NTIS)

A density-functional based tight binding method was used to study elementary steps in the growth of ultrananocrystalline (UNCD) diamond. It was shown previously that C(2) dimers are the dominant growth species in hydrogen- poor argon plasmas. Recent exper...

M. Sternberg P. Zapol T. Frauenheim J. Carlisle L. A. Curtiss

2001-01-01

272

Prevention of nanoscale wear in atomic force microscopy through the use of monolithic ultrananocrystaline diamond probes.  

SciTech Connect

Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) probes that results in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Diamond is potentially an ideal probe material due to its unrivaled hardness and stiffness, its low friction and wear, and its chemical inertness. However, the manufacture of monolithic diamond probes with consistently shaped small-radius tips has not been previously achieved. The first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes with <5-nm grain sizes and smooth tips with radii of 30-40 nm is reported, which are obtained through a combination of microfabrication and hot-filament chemical vapor deposition. Their nanoscale wear resistance under contact-mode scanning conditions is compared with that of conventional silicon nitride (SiN{sub x}) probes of similar geometry at two different relative humidity levels ({approx}15 and {approx}70%). While SiN{sub x} probes exhibit significant wear that further increases with humidity, UNCD probes show little measurable wear. The only significant degradation of the UNCD probes observed in one case is associated with removal of the initial seed layer of the UNCD film. The results show the potential of a new material for AFM probes and demonstrate a systematic approach to studying wear at the nanoscale.

Liu, J.; Grierson, D. S.; Notbohm, J.; Li, S.; O'Connor, S. D.; Turner, K. T.; Sumant, A. V.; Neelakantan, N.; Moldovan, N.; Carlisle, J. A.; Jaroenapibal, P.; Carpick, R. W. (Center for Nanoscale Materials); ( PSC-USR); (Univ. of Wisconsin at Madison); (Advanced Diamond Tech.); (Univ. of Pennsylvania)

2010-01-01

273

Layered Mantle Structure Beneath the Western Guyana Shield, Venezuela: Evidence From Diamonds and Xenocrysts in Guaniamo Kimberlites  

NASA Astrophysics Data System (ADS)

The Neo-Proterozoic (712 Ma) kimberlites from Guaniamo, Venezuela contain abundant low-Ca (harzburgitic) Cr-pyrope garnet xenocrysts, as well as lherzolitic Cr-pyropes, but few diamonds belonging to the peridotite-suite. Trace element compositions suggest three groupings of garnet. Most Cr-pyropes, both lherzolitic and harzburgitic, are highly depleted in magmaphile elements (e.g., Y < 5 ppm, Zr < 31 ppm) and have sinusoidal REE patterns. A second group (primarily lherzolites) has relatively undepleted characteristics (e.g., 9 - 14 ppm Y, Zr < 22 ppm), and typical LREE-depleted REE patterns. A few garnets show enrichment typical of peridotites metasomitised by relatively low-temperature mantle fluids (e.g., 7 - 9 ppm Y, 30 - 90 ppm Zr). Ni-in-garnet thermometry allows depths of origin to be estimated for the garnet xenocrysts by projecting temperatures onto the conductive geothermal gradient (40 Mw/m2 heat flow equivalent) obtained from compositions of Guaniamo Cr-diopside xenocrysts using the Nimis and Taylor method. Within the limited depth range of lithosphere sampled by the kimberlites (100-150 km) compositions vary considerably, but regularly, defining a strongly layered mantle section. Major and trace element compositions suggest the following lithologic sequence: highly-depleted lherzolite from 100 to 115 km, mixed ultra-depleted harzburgite and lherzolite from 115 to 120 km, relatively undepleted lherzolite from 120 to 135 km, mixed depleted harzburgite and relatively-undepleted lherzolite from 135 to 150 km. Based on comparison with well-documented mantle peridotites and xenocrysts from elsewhere, we conclude that the Meso-Proterozoic Cuchivero Province of the Guyana Shield (host to the Guaniamo kimberlites) is underlain by depleted and ultra-depleted shallow Archean mantle which was under-plated, and uplifted, by Proterozoic subduction, perhaps more than once. These Proterozoic subduction events introduced less-depleted oceanic lithosphere beneath the Archean section, which remained there and was the source of the abundant Guaniamo eclogite-suite diamonds that have ocean-floor carbon and oxygen isotope signatures. Although diamond-indicative low-Ca Cr-pyropegarnets are abundant, they were derived primarily from the shallow depleted layer within the field of graphite stability, and the rare peridotite-suite diamonds were either metastably preserved at these shallow depths, or were derived from the small amount of depleted lithosphere sampled by these kimberlites that remained within the diamond stability field (the mixture of Archean and Proterozoic mantle in the depth range 135-150 km).

Schulze, D. J.; Canil, D.; Channer, D. M.; Kaminsky, F. V.

2004-12-01

274

Structured polymer grafts on diamond.  

PubMed

In this work, a facile method for the preparation of structured and functional polymer grafts on diamond surfaces is described. Uniform poly(styrene) (PS) grafts with a thickness of approximately 110 nm were created directly onto oxidized ultrananocrystalline diamond (UNCD) surfaces by the self-initiated photografting and photopolymerization of bulk styrene with UV irradiation. The stable covalent bonding of the PS grafts allows polymer analogue reactions with drastic reaction conditions without noticeable detachment of the polymer coating. Thus, various functionalities, such as nitro, sulfonic, and aminomethyl groups have been successfully incorporated to the polymer grafts. Furthermore, the reactivity contrast between hydrogenated and oxidized UNCD surfaces allows for the preparation of structured polymer grafts. Finally, we have demonstrated the good reactivity and accessibility of the incorporated pendant functional groups. PMID:18034481

Steenackers, Marin; Lud, Simon Q; Niedermeier, Martin; Bruno, Paola; Gruen, Dieter M; Feulner, Peter; Stutzmann, Martin; Garrido, Jose A; Jordan, Rainer

2007-11-23

275

Structured polymer grafts on diamond.  

SciTech Connect

In this work, a facile method for the preparation of structured and functional polymer grafts on diamond surfaces is described. Uniform poly(styrene) (PS) grafts with a thickness of {approx}110 nm were created directly onto oxidized ultrananocrystalline diamond (UNCD) surfaces by the self-initiated photografting and photopolymerization of bulk styrene with UV irradiation. The stable covalent bonding of the PS grafts allows polymer analogue reactions with drastic reaction conditions without noticeable detachment of the polymer coating. Thus, various functionalities, such as nitro, sulfonic, and aminomethyl groups have been successfully incorporated to the polymer grafts. Furthermore, the reactivity contrast between hydrogenated and oxidized UNCD surfaces allows for the preparation of structured polymer grafts. Finally, we have demonstrated the good reactivity and accessibility of the incorporated pendant functional groups.

Steenackers, M.; Lud, S. Q.; Niedermeier, M.; Bruno, P.; Gruen, D. M.; Feulner, P.; Stutzmann, M.; Garrido, J. A.; Jordan, R.; Materials Science Division; Technische Univ. Munchen

2007-11-01

276

Surface Evaluation of Fluorinated Diamond-Like Carbon Thin Film as an Antisticking Layer of Nanoimprint Mold  

NASA Astrophysics Data System (ADS)

The surface property of fluorinated diamond-like carbon (F-DLC) thin film, which is expected to be a new antisticking layer of nanoimprint mold, was evaluated with reference to the commercial diamond-like carbon (DLC) thin film formed by radio-frequency (RF) plasma chemical vapor deposition (CVD) and the fluorinated self-assembled monolayer (SAM). From the measurement of X-ray photoelectron spectrum (XPS), the surface of the F-DLC thin film was found to be overspread with hydrophobic CFx components. In addition, the durability of the F-DLC thin film was evaluated by the contact angle measurement of a water drop against repeating times of the thermal imprint process. After over 100 times of imprinting, the contact angles of the F-DLC thin film were almost kept constant with the initial value and a fine replicated pattern was obtained. From these results, the F-DLC thin film was found to be suitable as a novel antisticking layer of the thermal nanoimprint mold.

Yamada, Noriko; Nakamatsu, Ken-ichiro; Kanda, Kazuhiro; Haruyama, Yuichi; Matsui, Shinji

2007-09-01

277

Magnetic Properties of Hydrogen?Terminated Surface Layer of Diamond Nanoparticles  

Microsoft Academic Search

Nanodiamonds (ND) with the mean size about 4–5 nm is an interesting object for studying electronic and magnetic properties of diamond surface throughout its high specific area. Chemically modified ND particle is a very promising new unique material for applications in molecular nano?electronics. Results of recent magnetic studies of pristine and hydrogen?terminated ND samples, obtained by detonation technique, are reported and

Vladimir Yu. Osipov; Marina Baidakova; Kazuyuki Takai; Toshiaki Enoki; Alexander Vul

2006-01-01

278

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

279

Diamond C 1s core-level excitons: Surface sensitivity  

NASA Astrophysics Data System (ADS)

The effect of surface termination on C 1s core-level bulk excitons found near the surface in single-crystal diamond is reported. By simultaneously recording bulk (total electron yield) and surface (partial electron yield) near-edge x-ray absorption fine-structure (NEXAFS) spectra with a range of single-crystal surface terminations, variable bulk exciton energy blueshifts and linewidth broadening were observed, most notably in the reconstructed single-crystal diamond. Investigation of polycrystalline diamond and ultrananocrystalline diamond films, using the same technique, allowed for a comparison between the reconstructed single-crystal diamond surface and nanodiamond bulk excitons. These findings suggest that surface-related effects can be misinterpreted as quantum confinement in some nanodiamond NEXAFS studies. Band bending is suggested as a possible contributor to these results.

Stacey, Alastair; Cowie, Bruce C. C.; Orwa, Julius; Prawer, Steven; Hoffman, Alon

2010-09-01

280

Diamond as a scaffold for bone growth.  

PubMed

Diamond is an attractive material for biomedical implants. In this work, we investigate its capacity as a bone scaffold. It is well established that the bioactivity of a material can be evaluated by examining its capacity to form apatite-like calcium phosphate phases on its surface when exposed to simulated body fluid. Accordingly, polycrystalline diamond (PCD) and ultrananocrystalline diamond (UNCD) deposited by microwave plasma chemical vapour deposition were exposed to simulated body fluid and assessed for apatite growth when compared to the bulk silicon. Scanning electron microscopy and X-ray photoelectron spectroscopy showed that both UNCD and PCD are capable of acting as a bone scaffold. The composition of deposited apatite suggests that UNCD and PCD are suitable for in vivo implantation with UNCD possible favoured in applications where rapid osseointegration is essential. PMID:23386207

Fox, Kate; Palamara, Joseph; Judge, Roy; Greentree, Andrew D

2013-02-06

281

Tribology of ultra high molecular weight polyethylene film on Si substrate with chromium nitride, titanium nitride and diamond like carbon as intermediate layers  

Microsoft Academic Search

This paper presents tribological studies on composite films consisting of different intermediate hard layers (chromium nitride (CrN), titanium nitride (TiN) and diamond like carbon (DLC)) on Si substrate followed by soft ultra high molecular weight polyethylene (4–5?m thick) as the top layer. The tribological properties of the composite films were evaluated on a ball-on-disc tribometer (composite film sliding against a

Myo Minn; Sujeet K. Sinha

2010-01-01

282

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

283

Electrical characteristics of hydrogen-terminated diamond metal-oxide-semiconductor with atomic layer deposited HfO2 as gate dielectric  

NASA Astrophysics Data System (ADS)

HfO2 films have been deposited on hydrogen-terminated diamond (H-diamond) by an atomic layer deposition (ALD) technique at 120 °C. Effect of rapid thermal annealing treatment on electrical properties of Au/Ti/Pd/ALD-HfO2/H-diamond metal-oxide-semiconductor (MOS) diodes has been investigated. The leakage current density of the MOS diode after annealing at 300 °C is as small as 10-8 A/cm2 at gate biases from -5.0 to 4.0 V. The capacitance-voltage curve in the depletion mode of the MOS diode after annealing is much sharper than that of the MOS diode before annealing and close to the theoretical dependence, which indicates the small interface state density. The annealed MOS diode is concluded to be more suitable for the fabrication of field effect transistors.

Liu, J. W.; Liao, M. Y.; Imura, M.; Oosato, H.; Watanabe, E.; Koide, Y.

2013-03-01

284

Studies on distribution of element contents in transient layer at interface between boron-doped diamond film electrode and tantalum substrate  

NASA Astrophysics Data System (ADS)

The boron-doped diamond film (BDD) grown on tantalum (Ta) substrate as an electrode (BDD/Ta) was prepared by hot filament chemical vapor deposition method. The experimental results demonstrated that our BDD/Ta had high current efficiency, strong ability to degrade wastewater, good corrosion stability and long lifetime. These excellent characteristics of BDD/Ta have been explained in terms of Rutherford backscattering (RBS) experiments. RBS investigation revealed that the continuous transient layer at the interface between boron-doped diamond film and Ta-substrate was formed and the microstructure of the continuous transient layer given by the continuous distribution of all element contents at the interface was obtained. The thicknesses of boron-doped diamond film and the continuous transient layer were about equal to 8000 × 10 15 atoms/cm 2 and 5800 × 10 15 atoms/cm 2, respectively. The formation of the continuous transient layer at the interface can eliminate the mismatch of thermal expansion coefficients (TEC) at the interface and only lead to the slow change of TEC because of the continuous distribution of element contents of the film and substrate in the transient layer at the interface. Thus, there is no residual stress to concentrate on the interface and the stress-corrosion delamination of the film disappears. Therefore, the corrosion stability and lifetime of BDD/Ta increase and last well, that have been verified by X-ray diffraction (XRD) experiments.

Liang, Jiachang; Gao, Chengyao; Zhang, Liping; Jiang, Lihui; Yang, Zhengquan; Wang, Zhiping; Ji, Chaohui; Le, Xiaoyun; Rong, Cuihua; Zhang, Jian

2011-05-01

285

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

286

Enhanced adhesion of diamond coatings  

Microsoft Academic Search

Diamond coatings are of interest for a wide range of applications due to the unique properties of crystalline diamond. Many applications require that the coating adhere strongly to metallic substrates which may have a large difference in thermal expansion coefficient with diamond. These substrates may also have undesirable chemical interactions with carbon during the deposition of the coatings. Intermediate layers

Zhido Zheng

2006-01-01

287

Diamond Schottky structures  

Microsoft Academic Search

Since Element Six reported in 2002 extremely high holes and electrons mobilities in intrinsic single crystal layers, synthetic diamond emerged as a promising semiconductor suitable for active electronic devices. Having the best physical and electrical theoretical properties among wide band gap semiconductors, diamond might become a serious competitor for silicon carbide (SiC) and gallium nitride (GaN) in the field of

M. Brezeanu

2009-01-01

288

Investigations on diamond nanostructuring of different morphologies by the reactive-ion etching process and their potential applications.  

PubMed

We report the systematic studies on the fabrication of aligned, uniform, and highly dense diamond nanostructures from diamond films of various granular structures. Self-assembled Au nanodots are used as a mask in the self-biased reactive-ion etching (RIE) process, using an O2/CF4 process plasma. The morphology of diamond nanostructures is a close function of the initial phase composition of diamond. Cone-shaped and tip-shaped diamond nanostructures result for microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films, whereas pillarlike and grasslike diamond nanostructures are obtained for Ar-plasma-based and N2-plasma-based ultrananocrystalline diamond (UNCD) films, respectively. While the nitrogen-incorporated UNCD (N-UNCD) nanograss shows the most-superior electron-field-emission properties, the NCD nanotips exhibit the best photoluminescence properties, viz, different applications need different morphology of diamond nanostructures to optimize the respective characteristics. The optimum diamond nanostructure can be achieved by proper choice of granular structure of the initial diamond film. The etching mechanism is explained by in situ observation of optical emission spectrum of RIE plasma. The preferential etching of sp(2)-bonded carbon contained in the diamond films is the prime factor, which forms the unique diamond nanostructures from each type of diamond films. However, the excited oxygen atoms (O*) are the main etching species of diamond film. PMID:23849039

Kunuku, Srinivasu; Sankaran, Kamatchi Jothiramalingam; Tsai, Cheng-Yen; Chang, Wen-Hao; Tai, Nyan-Hwa; Leou, Keh-Chyang; Lin, I-Nan

2013-07-26

289

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

290

Rapid thermal lysis of cells using silicon-diamond microcantilever heaters.  

PubMed

This paper presents the design and application of microcantilever heaters for biochemical applications. Thermal lysis of biological cells was demonstrated as a specific example. The microcantilever heaters, fabricated from selectively doped single crystal silicon, provide local resistive heating with highly uniform temperature distribution across the cantilevers. Very importantly, the microcantilever heaters were coated with a layer of 100 nm thick electrically insulating ultrananocrystalline diamond (UNCD) layer used for cell immobilization on the cantilever surface. Fibroblast cells or bacterial cells were immobilized on the UNCD/cantilever surfaces and thermal lysis was demonstrated via optical fluorescence microscopy. Upon electrical heating of the cantilever structures to 93 degrees C for 30 seconds, fibroblast cell and nuclear membrane were compromised and the cells were lysed. Over 90% of viable bacteria were also lysed after 15 seconds of heating at 93 degrees C. This work demonstrates the utility of silicon-UNCD heated microcantilevers for rapid cell lysis and forms the basis for other rapid and localized temperature-regulated microbiological experiments in cantilever-based lab on chip applications. PMID:20390131

Privorotskaya, Natalya; Liu, Yi-Shao; Lee, Jungchul; Zeng, Hongjun; Carlisle, John A; Radadia, Adarsh; Millet, Larry; Bashir, Rashid; King, William P

2010-03-12

291

Thermal Stabilization of Hole Channel on H-Terminated Diamond Surface by Using Atomic-Layer-Deposited Al2O3 Overlayer and its Electric Properties  

NASA Astrophysics Data System (ADS)

We have established an atomic-layer-deposited Al2O3 overlayer deposition method, which makes the H-surface-terminated p-type channel diamond surface thermally stable and completely keeps the concentration and mobility high even at 150 °C. In a range from 230 to 500 K, the mobility is proportional to the inverse of temperature showing a property characteristic for degenerate hole gas. The ionization energy is estimated to be 6.1 meV, indicating that holes are not generated mainly by thermal activation. This thermal stabilization technology enables us to measure hole properties up to 230 °C and to realize H-terminated diamond field-effect transistors with a reproducible high drain current.

Kasu, Makoto; Sato, Hisashi; Hirama, Kazuyuki

2012-02-01

292

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

293

Suiso Purazuma Jetto Ni Yoru Daiyamondo Gosei: Ropposho Daiyamondo Poritaipu No Xrd Patan Oyobi Kibanjo Kyokaiso No Shimyureshon (Synthesis of Diamond in a Hydrogen Plasma Jet: Simulations of Xrd Patterns of Diamond Polytypes and Boundary Layer on a Substrate).  

National Technical Information Service (NTIS)

Two kinds of diamond film were obtained by synthesizing diamond film on Mo substrates in a hydrogen plasma jet. One (type A) was random oriented cubic diamond film with clear habit planes. The other (type B) was film with no habit plane. It was inferred t...

N. Kikukawa M. Makino K. Maruyama M. Shiraishi

1993-01-01

294

Boron-doped diamond electrode: synthesis, characterization, functionalization and analytical applications.  

PubMed

In recent years, conductive diamond electrodes for electrochemical applications have been a major focus of research and development. The impetus behind such endeavors could be attributed to their wide potential window, low background current, chemical inertness, and mechanical durability. Several analytes can be oxidized by conducting diamond compared to other carbon-based materials before the breakdown of water in aqueous electrolytes. This is important for detecting and/or identifying species in solution since oxygen and hydrogen evolution do not interfere with the analysis. Thus, conductive diamond electrodes take electrochemical detection into new areas and extend their usefulness to analytes which are not feasible with conventional electrode materials. Different types of diamond electrodes, polycrystalline, microcrystalline, nanocrystalline and ultrananocrystalline, have been synthesized and characterized. Of particular interest is the synthesis of boron-doped diamond (BDD) films by chemical vapor deposition on various substrates. In the tetrahedral diamond lattice, each carbon atom is covalently bonded to its neighbors forming an extremely robust crystalline structure. Some carbon atoms in the lattice are substituted with boron to provide electrical conductivity. Modification strategies of doped diamond electrodes with metallic nanoparticles and/or electropolymerized films are of importance to impart novel characteristics or to improve the performance of diamond electrodes. Biofunctionalization of diamond films is also feasible to foster several useful bioanalytical applications. A plethora of opportunities for nanoscale analytical devices based on conducting diamond is anticipated in the very near future. PMID:19768202

Luong, John H T; Male, Keith B; Glennon, Jeremy D

2009-08-07

295

Dielectric properties of hydrogen-incorporated chemical vapor deposited diamond thin films.  

SciTech Connect

Diamond thin films with a broad range of microstructures from a ultrananocrystalline diamond (UNCD) form developed at Argonne National Laboratory to a microcrystalline diamond (MCD) form have been grown with different hydrogen percentages in the Ar/CH{sub 4} gas mixture used in the microwave plasma enhanced chemical vapor deposition (CVD) process. The dielectric properties of the CVD diamond thin films have been studied using impedance and dc measurements on metal-diamond-metal test structures. Close correlations have been observed between the hydrogen content in the bulk of the diamond films, measured by elastic recoil detection (ERD), and their electrical conductivity and capacitance-frequency (C-f) behaviors. Addition of hydrogen gas in the Ar/CH{sub 4} gas mixture used to grow the diamond films appears to have two main effects depending on the film microstructure, namely, (a) in the UNCD films, hydrogen incorporates into the atomically abrupt grain boundaries satisfying sp{sup 2} carbon dangling bonds, resulting in increased resistivity, and (b) in MCD, atomic hydrogen produced in the plasma etches preferentially the graphitic phase codepositing with the diamond phase, resulting in the statistical survival and growth of large diamond grains and dominance of the diamond phase, and thus having significant impact on the dielectric properties of these films.

Liu, C.; Xiao, X.; Wang, J.; Shi, B.; Auciello, O.; Carlisle, J. A.; Carpick, R.; Adiga, V.; Univ. of Wisconsin at Madison; Univ. of Pennsylvania

2007-01-01

296

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

297

Laser cutting of CVD diamond wafers  

Microsoft Academic Search

CVD diamond has many outstanding physical properties. Because of its extreme hardness, this material is difficult to cut and polish and laser cutting and shaping is a technology of choice. Thick polycrystalline diamond layers were deposited by microwave plasma enhanced chemical vapor deposition on silicon substrates. After synthesis, the silicon substrate was dissolved in an acid mixture and diamond wafer

Hana Chmelickova; Milan Vanecek; Jan Rosa; Martin Stranyanek

2005-01-01

298

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

299

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

300

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

301

Nanocrystalline Diamond Films for Biosensor Applications  

NASA Astrophysics Data System (ADS)

Diamond is a material with quite a number of excellent properties, like extreme hardness, high elastic modulus, high wear resistance, optical transparency in a broad spectral range, resistivity controllable by the level of dopants, etc. which make it a promising candidate for different sensor applications, e.g. for X-ray detection. Due to its outstanding electrochemical properties, superior chemical inertness and biocompatibility, artificially grown diamond has been recognised as an extremely attractive material for both (bio-)chemical sensing and as an interface to biological systems. This holds for all forms of diamond: monocrystalline (natural or artificial) and poly- (PCD), nano- (NCD) and ultrananocrystalline (UNCD) films. This paper is devoted to possible biosensor application of NCD and UNCD films. The first part will briefly introduce UNCD films (composed of diamond nanocrystallites of 3-5 nm diameter embedded in an amorphous carbon matrix with a grain boundary thickness of 1.0-1.5 nm), their deposition by microwave plasma chemical vapour deposition, their growth mechanisms and the characterization of their bulk properties, comparing them with other types of diamond films. The second part deals with surface modifications of UNCD films, which is the first step towards preparation of a biosensor, including different plasma and chemical processes, the thorough characterization of the resulting surfaces by a variety of techniques (AFM, XPS, ToF-SIMS, contact angle measurements, etc.) and the possibility to pattern the surface properties. The third part will describe possible pathways for the immobilization of biomolecules (proteins, DNA) on UNCD surfaces and the techniques for the characterization of this step, including force measurements, AFM and spectroscopic analyses. In the final part, different examples of biosensors based on UNCD as well as on NCD will be demonstrated in order to reveal the potential of diamond (films) in this field.

Popov, Cyril; Kulisch, Wilhelm

302

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

303

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

304

Deposition of Diamond Films on Copper Substrate  

NASA Astrophysics Data System (ADS)

The direct deposition of diamond films on copper substrate has been suffered from adhesion problems due to the mismatch of the thermal expansion coefficients of diamond and copper. In this paper, nuclei with valuable density were directly introduced through a submicron diamond powder layer. The diamond grits partially were buried in the copper substrate leading to better adhesion. Another method with nickel intermediate layer for enhancing the adhesion was studied here in detail. It was suggested that Cu-Ni eutectic between the copper substrate and Ni interlayer might contribute to the adhesion improvement. The quality of the diamond films deposited with nickel interlayer was investigated by scanning electron microscopy and Raman spectroscopy.

Ma, Zhi-bin; Wu, Qin-chong; Shu, Xing-sheng; Wang, Jian-hua; Wang, Chuan-xin; Li, Xiang-feng

2000-04-01

305

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.

306

Micromachining of diamond probes for atomic force microscopy applications  

Microsoft Academic Search

We realized IC-compatible diamond atomic force microscope (AFM) probe technology using our newly developed anodic bonding technique of 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 500°C, with an electric voltage of 600V, and

Kazuya Unno; Takayuki Shibata; Eiji Makino

2001-01-01

307

Characterisation of diamond coatings with different morphologies by Raman spectroscopy using various laser wavelengths.  

PubMed

Since the beginning of low-pressure diamond synthesis, Raman spectroscopy has been widely used to identify and characterise the quality of diamonds. The diamond crystal is characterised by a Raman peak at about 1,332 cm(-1). Other peaks are associated with miscellaneous carbon structures, e.g. graphite and amorphous phases. In recent years, both well-faceted crystalline diamonds and nanocrystalline and ultrananocrystalline diamonds have been investigated. For these fine-grained materials, the diamond peak at 1,332 cm(-1) disappears and the intensities of peaks at other wavelengths increase. To study the influence of the Raman laser wavelength, three lasers were used (472.681 nm, blue; 532.1 nm, green; 632.81 nm, red). For well-faceted diamonds, the Raman spectra with blue and green laser light were similar. A shift of the peak maxima and different intensities were observed. With use of the red laser, a strong luminescence peak and low peak intensities for the various carbon-related peaks occurred. When the diamond morphology changes from well-faceted to fine-grained ballas diamond, the spectra are similar for all three lasers. PMID:22362277

Rudigier, Moritz; Haubner, Roland

2012-02-24

308

The effect of tungsten buffer layer on the stability of diamond with tungsten carbide–cobalt nanocomposite powder during spark plasma sintering  

Microsoft Academic Search

WC–Co nanocomposite powder produced by spray pyrolysis–continuous reduction and carbonization technology, diamond coated with tungsten (W) by vacuum vapor deposition and uncoated diamond were used in this study. This work adopted the spark plasma sintering (SPS) process to prepare diamond-enhanced ultrafine WC–Co cemented carbide composite material. The effects of W buffer on the stability of diamond with WC–Co nanocomposite powder

X. L. Shi; G. Q. Shao; X. L. Duan; Z. Xiong; H. Yang

2006-01-01

309

Diamond photonics  

Microsoft Academic Search

Diamond, a material marvelled for its strength, beauty and perfection, was first used to polish stone axes in Neolithic times. This most ancient of materials is now being touted by many as the ideal platform for quantum-age technologies. In this Review, we describe how the properties of diamond match the requirements of the 'second quantum revolution'. We also discuss recent

Igor Aharonovich; Andrew D. Greentree; Steven Prawer

2011-01-01

310

The induction of nanographitic phase on Fe coated diamond films for the enhancement in electron field emission properties  

NASA Astrophysics Data System (ADS)

A thin layer of iron coating and subsequent post-annealing (Fe-coating/post-annealing) is seen to significantly enhance the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films. The best EFE properties, with a turn on field (E0) of 1.98 V/?m and current density (Je) of 705 ?A/cm2 at 7.5 V/?m, are obtained for the films, which were Fe-coated/post-annealed at 900 °C in H2 atmosphere. The mechanism behind the enhanced EFE properties of Fe coated/post-annealed UNCD films are explained by the microstructural analysis which shows formation of nanographitic phase surrounding the Fe (or Fe3C) nanoparticles. The role of the nanographitic phase in improving the emission sites of Fe coated/post-annealed UNCD films is clearly revealed by the current imaging tunneling spectroscopy (CITS) images. The CITS images clearly show significant increase in emission sites in Fe-coated/post-annealed UNCD films than the as-deposited one. Enhanced emission sites are mostly seen around the boundaries of the Fe (or Fe3C) nanoparticles which were formed due to the Fe-coating/post-annealing processes. Moreover, the Fe-coating/post-annealing processes enhance the EFE properties of UNCD films more than that on the microcrystalline diamond films. The authentic factor, resulting in such a phenomenon, is attributed to the unique granular structure of the UNCD films. The nano-sized and uniformly distributed grains of UNCD films, resulted in markedly smaller and densely populated Fe-clusters, which, in turn, induced more finer and higher populated nano-graphite clusters.

Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K.; Chen, H.-C.; Huang, P.-C.; Shih, W.-C.; Lo, S.-C.; Lin, L.-J.; Lee, C.-Y.; Lin, I.-N.

2013-03-01

311

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

312

Diamond Electronic Devices  

SciTech Connect

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 deg.n 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 ({approx}1 nm) doped layers in order to achieve high RT activation.

Isberg, J. [Division for Electricity, Uppsala University, Box 534, S-751 21 Uppsala (Sweden)

2010-11-01

313

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

314

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

315

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.

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, Sebastien; Twittchen, Daniel; Markham, Matthew; Dregely, Daniel; Giessen, Harald; Meijer, Jan; Jelezko, Fedor; Nebel, Christoph E; Bratschitsch, Rudolf; Leitenstorfer, Alfred; Wrachtrup, Jorg

2012-01-01

316

Diamond coatings exposure to fusion-relevant plasma conditions  

NASA Astrophysics Data System (ADS)

Several types of diamond layers have been deposited on molybdenum tiles by chemical vapour deposition techniques, and exposed under erosion-dominated conditions in the SOL of TEXTOR in order to assess them as a suitable candidate for plasma-facing material. Post-exposure characterisation of physical properties and surface modification induced by the plasma was performed by SEM imaging, investigation of diamond surface by micro-Raman spectroscopy and deuterium retention measurements by NRA. The analyses evidenced that lightly boron-doped micro-crystalline diamond is performing better than undoped and heavily doped samples, and nano-crystalline diamond and diamond-like carbon, as it showed lower surface modification, lower presence of arcing traces at the surface and lower deuterium retention. High concentration of boron in the layers led to higher retention of deuterium, whereas undoped (insulating) diamond showed increased arcing activity. Nano-crystalline diamond and diamond-like carbon layers generally showed poorer mechanical properties.

Porro, S.; Temmerman, G. De; Lisgo, S.; Rudakov, D. L.; Litnovsky, A.; Petersson, P.; John, P.; Wilson, J. I. B.

2011-08-01

317

Thermally induced alkylation of diamond.  

PubMed

We present an approach for the thermally activated formation of alkene-derived self-assembled monolayers on oxygen-terminated single and polycrystalline diamond surfaces. Chemical modification of the oxygen and hydrogen plasma-treated samples was achieved by heating in 1-octadecene. The resulting layers were characterized using X-ray photoelectron spectroscopy, thermal desorption spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. This investigation reveals that alkenes selectively attach to the oxygen-terminated sites via covalent C-O-C bonds. The hydrophilic oxygen-terminated diamond is rendered strongly hydrophobic following this reaction. The nature of the process limits the organic layer growth to a single monolayer, and FTIR measurements reveal that such monolayers are dense and well ordered. In contrast, hydrogen-terminated diamond sites remain unaffected by this process. This method is thus complementary to the UV-initiated reaction of alkenes with diamond, which exhibits the opposite reactivity contrast. Thermal alkylation increases the range of available diamond functionalization strategies and provides a means of straightforwardly forming single organic layers in order to engineer the surface properties of diamond. PMID:21090790

Hoeb, Marco; Auernhammer, Marianne; Schoell, Sebastian J; Brandt, Martin S; Garrido, Jose A; Stutzmann, Martin; Sharp, Ian D

2010-11-23

318

Extreme synthesis and chemical doping of diamond aerogel  

NASA Astrophysics Data System (ADS)

Amorphous carbon aerogels have attracted much interest in recent years due to their low density, large intrinsic surface areas (>1000 m^2/g), large pore volume, low dielectric constant, and high strength. We use high-pressure (˜20 GPa) laser-heating (>600 C) within a diamond anvil cell (DAC) to convert the amorphous network of a low-density (40mg/cc) carbon aerogel into an ultrananocrystalline diamond aerogel. Photoluminescence spectroscopy and confocal time-correlated single-photon counting indicate the recovered material contains both negatively-charged and neutral nitrogen-vacancy (NV) complexes. Synchrotron scanning transmission x-ray microscopy (STXM) is used to compare the carbon electronic density-of-states of the amorphous starting material with the recovered diamond aerogel with ˜100 meV energy resolution. Finally, we use nanoscale secondary ion mass spectrometry to investigate doping of the resorcinol-formaldehyde starting material with the aim of chemically tuning heteroatomic point defects within this diamond material system.

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Wang, Yinmin; Kilcoyne, A. L. D.; Weber, Peter K.; Willey, Trevor M.; Visbeck, Kenneth S.; Evans, William J.; Satcher, Joe H., Jr.

2010-03-01

319

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Studies of diamond-like carbon (DLC) films deposited on stainless steel substrate with Si\\/SiC intermediate layers  

Microsoft Academic Search

In this work, diamond-like carbon (DLC) films were deposited on stainless steel substrates with Si\\/SiC intermediate layers by combining plasma enhanced sputtering physical vapour deposition (PEUMS-PVD) and microwave electron cyclotron resonance plasma enhanced chemical vapour deposition (MW-ECRPECVD) techniques. The influence of substrate negative self-bias voltage and Si target power on the structure and nano-mechanical behaviour of the DLC films were

Jing Wang; Gui-Chang Liu; Li-Da Wang; Xin-Lü Deng; Jun Xu

2008-01-01

320

Electrical stimulation of retinal ganglion cells with diamond and the development of an all diamond retinal prosthesis.  

PubMed

Electronic retinal implants for the blind are already a market reality. A world wide effort is underway to find the technology that offers the best combination of performance and safety for potential patients. Our approach is to construct an epi-retinally targeted device entirely encapsulated in diamond to maximise longevity and biocompatibility. The stimulating array of our device comprises a monolith of electrically insulating diamond with thousands of hermetic, microscale nitrogen doped ultra-nanocrystalline diamond (N-UNCD) feedthroughs. Here we seek to establish whether the conducting diamond feedthroughs of the array can be used as stimulating electrodes without further modification with a more traditional neural stimulation material. Efficacious stimulation of retinal ganglion cells was established using single N-UNCD microelectrodes in contact with perfused, explanted, rat retina. Evoked rat retinal ganglion cell action potentials were recorded by patch clamp recording from single ganglion cells, adjacent to the N-UNCD stimulating electrode. Separately, excellent electrochemical stability of N-UNCD was established by prolonged pulsing in phosphate buffered saline at increasing charge density up to the measured charge injection limit for the material. PMID:22613134

Hadjinicolaou, Alex E; Leung, Ronald T; Garrett, David J; Ganesan, Kumaravelu; Fox, Kate; Nayagam, David A X; Shivdasani, Mohit N; Meffin, Hamish; Ibbotson, Michael R; Prawer, Steven; O'Brien, Brendan J

2012-05-20

321

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

322

Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.  

PubMed

In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are suitable for probing, manipulating, sculpting, and sensing at single digit nanoscale. PMID:21534601

Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

2011-05-18

323

Optimised plasma enhanced chemical vapour deposition (PECVD) process for double layer diamond-like carbon (DLC) deposition on germanium substrates  

Microsoft Academic Search

Double layer DLC-films were deposited on germanium substrates by the PECVD-method, using ethyne as reactant gas during RF plasma excitation in a parallel plate reactor. The electric field distribution in the plasma chamber was simulated by FEM. The basic concept was the utilization of coatings with graded interfaces and without other materials.The bias voltage, working pressure and substrate temperature were

Jan Heeg; Markus Rosenberg; Christian Schwarz; Torsten Barfels; Marion Wienecke

2008-01-01

324

Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices  

Microsoft Academic Search

MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. A major problem with the Si-based MEMS technology is that Si has poor mechanical and tribological properties [J.J. Sniegowski, in: B. Bushan (Ed.), Tribology Issues and Opportunities in MEMS, Kluwer Academic Publisher, The Netherlands, 1998, p. 325; A.P. Lee, A.P. Pisano, M.G. Lim, Mater. Res.

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

2001-01-01

325

Ultrananocrystalline diamond film as an optimal cell interface for biomedical applications  

Microsoft Academic Search

Surfaces of materials that promote cell adhesion, proliferation, and growth are critical for new generation of implantable\\u000a biomedical devices. These films should be able to coat complex geometrical shapes very conformally, with smooth surfaces to\\u000a produce hermetic bioinert protective coatings, or to provide surfaces for cell grafting through appropriate functionalization.\\u000a Upon performing a survey of desirable properties such as chemical

Piyush Bajaj; Demir Akin; Amit Gupta; Debby Sherman; Bing Shi; Orlando Auciello; Rashid Bashir

2007-01-01

326

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

National Technical Information Service (NTIS)

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 invol...

O. Auciello D. M. Gruen A. R. Krauss A. Jayatissa A. Sumant J. Tucek D. Mancini N. Moldovan A. Erdemir D. Ersoy

2000-01-01

327

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

Microsoft Academic Search

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

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

2000-01-01

328

Nanostructured Diamond  

NASA Astrophysics Data System (ADS)

In the recent years, diamonds with diameter distributions peaked around 3 nanometers have been evidenced in an intriguing variety of environments : on meteorites, comets and in detonation residues, but also in diamond films produced under specific (low) hydrogen partial pressures in CVD experiments and even in petroleum (diamondoids). If diamond particles get more stable than their graphitic counterparts in the nanometer range, the competition between those two structures and the effect of size reduction make the properties of nanoscale diamond unique. We address the properties of nanoscale diamond using first-principles molecular dynamics simulation. Structural models are obtained for sizes up to 3 nanometers and their optical properties, computed using Time-Dependent Density Functional Theory, are compared to X-ray absorption and emission spectra. We conclude that, contrary to silicon and germanium, there is no more a quantum confinement effect on the optical gap above sizes of 2-3 nanometers [1]. Also for these sizes, specific surface reconstructions that have signatures in the aborption spectra occur : the particle's diamond core gets surrounded by fullerene-like caps. We studied surface reconstructions as a function of hydrogen chemical potential. These model simulations indicate that for sizes of about 2 nanometers, surface hydrogen tends to be released, favoring fullerene-like surface reconstructions. This provides an explanation for the similar size distributions of nanodiamonds produced under extremely different temperature/pressure conditions [2]. We also show that below some hydrogen potential value threshold, the CVD process of diamond film would lead to an agglomeration of nanodiamonds (called UltraNanocrystallineDiamond) rather than the growth of bulk diamond, as observed experimentally. Finally we discuss the possibility of N-doping nanodiamonds and show that the nitrogen incorporation is very much dependent on the particle size and affected by the surface reconstructions. This work has been done in collaboration with Dr. Giulia Galli under the auspices of the U.S. DOE at the University of California/LLNL under contract No W-7405-Eng-48 and was supported by the FNRS. [1] Physical Review Letters 90 (2003) 037401-1 [2] Nature Materials 2 (2003) 792

Raty, Jean-Yves

2004-03-01

329

CVD diamond films for synchrotron radiation beam monitoring  

Microsoft Academic Search

Free-standing polycrystalline diamond films grown by microwave plasma CVD technique were tested for detection X- ray radiation from a synchrotron source. Two different configurations of collection electrodes on diamond were used. The first (sandwich) geometry uses a thin amorphous conducting layers formed by nitrogen ion irradiation on both sides of the diamond plate. The second (planar) one, which showed better

Sultan B. Dabagov; Igor I. Vlasov; Violetta A. Murashova; Mikhail V. Negodaev; Victor G. Ralchenko; Rustem V. Fedorchuk; Mikhail N. Yakimenko

1999-01-01

330

Amorphous-diamond electron emitter  

DOEpatents

An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

Falabella, Steven (Livermore, CA)

2001-01-01

331

Pulse-doped diamond p-channel metal semiconductor field-effect transistor  

Microsoft Academic Search

A p-type diamond metal semiconductor field-effect transistor (MESFET) structure, utilizing a boron pulse-doped layer as the conducting channel, has been successfully fabricated. The pulse-doped structure consists of an undoped diamond buffer layer, a highly doped thin diamond active layer, and an undoped diamond cap layer grown by the microwave plasma assisted chemical vapor deposition method. It is shown that this

Hiromu Shiomi; Yoshiki Nishibayashi; Naohiro Toda; Shin-ichi Shikata

1995-01-01

332

Recent advances in electrochemistry of diamond  

Microsoft Academic Search

Conductive boron-doped chemically vapour-deposited diamond thin film and honeycomb electrodes were examined for various possible applications in electroanalysis and electric double layer capacitor applications, respectively. The possibility of voltammetric study of electrochemical reactions occurring at high oxidation and high reduction potentials was demonstrated at diamond electrodes, taking histamine and carbon tetrachloride as respective examples. High sensitivity and high stability of

T. N. Rao; A. Fujishima

2000-01-01

333

Processing of functionally graded tungsten carbide-cobalt-diamond composites  

Microsoft Academic Search

Polycrystalline diamond compacts (PDCs) are widely used as drill bit cutters in rock drilling and as tool bits in machining non-ferrous materials. A typical PDC comprises a thin layer of sintered polycrystalline diamond bonded to a tungsten carbide-cobalt substrate. A well recognized failure mechanism is delamination at the interface between diamond and cemented carbide. High stresses at the diamond\\/carbide interface,

Mohit Jain

2001-01-01

334

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

335

Optical properties of diamond  

Microsoft Academic Search

Because of its excellent thermal-mechanical properties, diamond is a promising infrared window material. With the development of chemical vapor deposition (CVD) diamond technology, diamond windows and domes are becoming a practical reality. The infrared transmittance of type IIa and CVD diamond was characterized as a function of temperature, and the room-temperature ultraviolet transmittance of type IIa diamond was also measured.

Michael E. Thomas; William J. Tropf

1994-01-01

336

Heteroepitaxial Diamond Growth.  

National Technical Information Service (NTIS)

Progress continued in 1992 in the two major thrust areas of the diamond program; diamond consolidation, and heteroepitaxial nucleation. We have been developing a consolidation technology as one approach to large area diamond single crystals. During this p...

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

1993-01-01

337

Diamond. Part 2  

Microsoft Academic Search

A brief review is given of some recent solid-state physics studies made on diamond. These include both the ultra-violet and the infra-red absorption spectra of diamond; the classification of diamonds; a survey of the semiconducting properties exhibited by some diamonds; diamond luminescence; and some of the effects produced when diamonds are subjected to irradiation by high energy particles and by

S. Tolansky

1960-01-01

338

Silicon-on-Diamond — An engineered substrate for electronic applications  

Microsoft Academic Search

Silicon on Diamond (SOD) is a substrate engineered to address the major challenges of silicon-based ULSI technology, in particular, to provide for enhanced thermal management and charge confinement. The SOD concept is achieved by joining a thin, single crystalline Si device layer to a highly oriented diamond (HOD) layer that serves as an electrical insulator, heat spreader and supporting substrate.

A. Aleksov; J. M. Gobien; X. Li; J. T. Prater; Z. Sitar

2006-01-01

339

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

340

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

341

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

342

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

343

Diamond Industry Resolves to Ban "Conflict Diamonds"  

NSDL National Science Digital Library

The 29th World Diamond Congress met last week from July 16 to July 19 in Antwerp, Belgium where the issue of "conflict diamonds," diamonds mined from warring countries including Sierra Leone and Angola, was the dominating topic. Conflict diamonds have fueled and funded wars in these countries, as well as led to the murder and mutilation of thousands of people. These conflict diamonds are estimated to account for four percent of $6.8 billion diamond production industry. On July 19, at the end of the Congress, a resolution was introduced by International Diamond Manufacturers Association (IDMA) and the World Federation of Diamond Bourses, which calls for an international system of certifying gemstones's origins, as well as a registry to monitor the sales, imports, and exports of the precious stones. The resolution was unanimously endorsed, including the approval of De Beers, the diamond trader that controls 60 percent of the entire diamond supply. The IDMA and the World Federation of Diamond Bourses believe that these measures will be implemented by the end of the year.

Missner, Emily D.

344

Diamondization of chemically functionalized graphene and graphene-BN bilayers.  

PubMed

In this article, based on first-principles calculations, we systematically study functionalization induced diamondization of graphene bilayer and graphene-BN hybrid bilayer. With single-side functionalization, the diamondized structures are magnetic semiconductors. 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 a nonmagnetic metal. The tunable electronic and magnetic properties pave new avenues to construct graphene-based electronics and spintronics devices. PMID:22569845

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

2012-05-08

345

Carbon dimers on the diamond (100) surface : growth and nucleation.  

SciTech Connect

We use a density-functional based tight-binding method to study diamond growth by C{sub 2} on a nonhydrogenated diamond (100)-(2 x 1) surface. The study is motivated by advances in the growth of ultrananocrystalline diamond (UNCD) films under hydrogen-poor conditions. We identify and classify stable adsorbate configurations formed above dimer rows and troughs on the reconstructed surface. We also investigate adsorption and migration barriers using the nudged elastic band method. We find viable adsorption pathways leading to chain growth and step advancement. Initial depositions proceed without barriers into topologically imperfect configurations. The most stable configuration is a growth position that bridges two adjacent surface dimers along a dimer row. It is reached over a barrier of 1.2 eV and has an adsorption energy of -6.9 eV. Many other configurations exist that have adsorption energies differing by up to 2.7 eV. By comparison, analogous structures for silicon are fewer in number and closer in energy because Si lacks {pi} bonding, which is important for C{sub 2} on diamond. Migration barriers for ad-dimers are in the range of 2-3 eV due to relatively large differences in the energies of intermediate local minima. Comparing our results with previous studies on the (110) surface, we note that barriers leading to growth are higher and pathways are more complex on the (100) surface. The barriers suggest that reactions leading to both growth and re-nucleation are possible, which helps to understand the small observed grain sizes in UNCD.

Sternberg, M.; Zapol, P.; Curtiss, L. A.; Materials Science Division

2003-11-01

346

Fabrication of high frequency ZnO thin film SAW devices on silicon substrate with a diamond-like carbon buffer layer using RF magnetron sputtering  

Microsoft Academic Search

Diamond-like carbon (DLC) film is a promising candidate for surface acoustic wave (SAW) device applications because of its higher acoustic velocity. A zinc oxide (ZnO) thin film has been deposited on DLC film\\/Si substrate by RF magnetron sputtering; the optimized parameters for the ZnO sputtering are RF power density of 0.55W\\/cm2, substrate temperature of 380°C, gas flow ratio (Ar\\/O2) of

Wen-Ching Shih; Rei-Ching Huang

2008-01-01

347

Bioimaging Applications Using Color Centers in Diamond  

NASA Astrophysics Data System (ADS)

Color centers in diamond offer significant opportunities for the development of new techniques in bioimaging. We present recent work on the application of various color centers in nanodiamond as cathodoluminescent probes for efficient correlative microscopy. We also discuss progress on the use of bulk diamond samples with surface-implanted nitrogen-vacancy (NV) layers for magnetic field sensing, with the specific goal of making sensitive, spatially-localized measurements of free radical concentrations in biological systems.

Glenn, David; Zhang, Huiliang; Benado, Anat; Kasthuri, Narayanan; Schalek, Richard; Lichtman, Jeff; Walsworth, Ronald

2012-06-01

348

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

349

Comprehensive Investigation of Single Crystal Diamond Deep-Ultraviolet Detectors  

NASA Astrophysics Data System (ADS)

The wide bandgap of diamond, along with its extreme semiconductor properties, offers the promising route for deep-ultraviolet (DUV) detection, especially under solar-blind condition and harsh environments. The ideal photodetector should generally satisfy the 5S requirements such as high sensitivity, high signal-to-noise ratio, high spectral selectivity, high speed, and high stability. In this paper, we comprehensively investigate the DUV detectors fabricated from various kinds of single crystal diamonds such as boron-doped diamond homoepitaxial layer, intrinsic diamond homoepitaxial layers with different thicknesses, and single crystal diamond substrates. The post process such as hydrogen plasma treatment on the performance of the DUV detectors is also examined. The strategies to develop high-performance diamond DUV detectors are provided.

Liao, Meiyong; Sang, Liwen; Teraji, Tokuyuku; Imura, Masataka; Alvarez, Jose; Koide, Yasuo

2012-09-01

350

Ion implantation of diamond: Damage, doping, and lift-off  

SciTech Connect

In order to make good quality economical diamond electronic devices, it is essential to grow films and to dope these films to obtain n- and p- type conductivity. This review talk discuss first doping by ion implantation plus annealing of the implantation damage, and second flow to make large area single crystal diamonds. C implantation damage below an estimated Frenkel defect concentration of 7% could be recovered almost completely by annealing at 950C. For a defect concentration between 7 and 10%, a stable damage form of diamond (``green diamond``) was formed by annealing. At still higher damage levels, the diamond graphitized. To introduce p-type doping, we have co-implanted B and C into natural diamond at 77K, followed by annealing up to 1100C. The resulting semiconducting material has electrical properties similar to those of natural B-doped diamond. To create n-type diamond, we have implanted Na{sup +}, P+ and As{sup +} ions and have observed semiconducting behavior. This has been compared with carbon or noble element implantation, in an attempt to isolate the effect of radiation damage. Recently, in order to obtain large area signal crystals, we have developed a novel technique for removing thin layers of diamond from bulk or homoepitaxial films. This method consists of ion implantation, followed by selective etching. High energy (4--5 MeV) implantation of carbon or oxygen ions creates a well-defined layer of damaged diamond buried at a controlled depth. This layer is graphitized and selectivity etched either by heating at 550C in an oxygen ambient or by electrolysis. This process successfully lifts off the diamond plate above the graphite layer. The lift-off method, combined with well-established homoepitaxial growth processes, has potential for fabrication of large area single-crystal diamond sheets.

Parikh, N.R.; McGucken, E.; Swanson, M.L. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy; Hunn, J.D.; White, C.W.; Zuhr, R.A. [Oak Ridge National Lab., TN (United States)

1993-09-01

351

A Diamond's Deep History  

NSDL National Science Digital Library

While diamonds play a significant role in many cultures, the Earth processes that create diamonds are less familiar to many people. With the use of Macromedia Flash Player, Thirteen/NET New York educates the public about the formation of diamonds two to three billion years ago deep underground. Users can learn about indicator minerals, kimberlite chimneys, and secondary diamond deposits. Through the colorful illustrations and animations, the website offers a great introduction to the creation of this desirable stone.

352

Electrically conductive diamond electrodes  

DOEpatents

An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

Swain, Greg (East Lansing, MI); Fischer, Anne (Arlington, VA),; Bennett, Jason (Lansing, MI); Lowe, Michael (Holt, MI)

2009-05-19

353

Picturing Blood Diamonds  

Microsoft Academic Search

Diamonds traded on black markets for weapons used in civil war are known as ‘blood diamonds’. This article examines how blood diamonds have been constructed by images deployed in the ongoing contest over the meaning of these gems. On the one hand, corporations and governments transfigure rocks into gems through marketing and by defining the boundaries of a ‘licit’ trade.

Susan Falls

2011-01-01

354

Polycrystalline Diamond: Manufacture, Wear Mechanisms, and Implications for Bit Design  

Microsoft Academic Search

This paper focuses on the failure modes of polycrystalline-diamond-compact (PDC) cutters and discusses efforts to improve impact resistance, thermal stability, and hydraulic cooling. Composite-transition-layer technology has made possible a new generation of polycrystalline-diamond (PCD) -enhanced inserts that can be used in percussion and roller-cone applications.

M. V. Sneddon; D. R. Hall

1988-01-01

355

Polycrystalline diamond - Manufacture, wear mechanisms, and implications for bit design  

SciTech Connect

This paper focuses on the failure modes of polycrystalline-diamond-compact (PDC) cutters and discusses efforts to improve impact resistance, thermal stability, and hydraulic cooling. Composite-transition-layer technology has made possible a new generation of polycrystalline-diamond (PCD) -enhanced inserts that can be used in percussion and roller-cone applications.

Sneddon, M.V. (Smith Megadiamond (US)); Hall, D.R. (Novatek)

1988-12-01

356

Magnetic properties of segregated layers containing M(II)3(?3-OH)2 (M = Co or Ni) diamond chains bridged by cis,cis,cis-1,2,4,5-cyclohexanetetracarboxylate.  

PubMed

We report the hydrothermal synthesis, X-ray crystal structures, and thermal, optical, and magnetic properties of two isostructural layered coordination polymers, [M(II)(5)(OH)(2)(chtc)(2)(H(2)O)(10)]·2H(2)O where M = Co (1Co) or Ni (2Ni) and chtc = cis,cis,cis-1,2,4,5-cyclohexanetetracarboxylate. The structures consist of segregated layers where each layer is formed of M(3)(OH)(2) diamond chains, involving edge- and corner-sharing octahedra, bridged by M(chtc)(2). In the space created by the chains and the bridges exists channels, which house the coordinated and noncoordinated water molecules, all hydrogen bonded to form a dodecamer, with a central cyclohexane chair shape ring. Interestingly, the water molecules of 2Ni are more difficult to remove than those of 1Co, but pyrolysis of the latter takes place at higher temperature. The magnetic properties are characterized by Ne?el transition to fully compensated antiferromagnets at 5.8 K (1Co) and 3.0 K (2Ni). The moments are easily reversed in an applied field of 150 Oe (1Co) and 300 Oe (2Ni) to a ferrimagnet with one uncompensated moment followed by a nonlinear increase to a saturation corresponding to a ferrimagnet with three uncompensated moments. Further, point charge calculations to estimate the weak bonding energies between the various types of interaction are reported. PMID:20860368

Kurmoo, Mohamedally; Otsubo, Kazuya; Kitagawa, Hiroshi; Henry, Marc; Ohba, Masaaki; Takagi, Seishi

2010-10-18

357

Wear-resistant diamond nanoprobe tips with integrated silicon heater for tip-based nanomanufacturing.  

PubMed

We report exceptional nanoscale wear and fouling resistance of ultrananocrystalline diamond (UNCD) tips integrated with doped silicon atomic force microscope (AFM) cantilevers. The resistively heated probe can reach temperatures above 600 degrees C. The batch fabrication process produces UNCD tips with radii as small as 15 nm, with average radius 50 nm across the entire wafer. Wear tests were performed on substrates of quartz, silicon carbide, silicon, or UNCD. Tips were scanned for more than 1 m at a scan speed of 25 mum s(-1) at temperatures ranging from 25 to 400 degrees C under loads up to 200 nN. Under these conditions, silicon tips are partially or completely destroyed, while the UNCD tips exhibit little or no wear, no signs of delamination, and exceptional fouling resistance. We demonstrate nanomanufacturing of more than 5000 polymer nanostructures with no deterioration in the tip. PMID:20481445

Fletcher, Patrick C; Felts, Jonathan R; Dai, Zhenting; Jacobs, Tevis D; Zeng, Hongjun; Lee, Woo; Sheehan, Paul E; Carlisle, John A; Carpick, Robert W; King, William P

2010-06-22

358

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

359

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

360

Electrical properties of boron-doped diamond films synthesized by MPCVD on an iridium substrate  

Microsoft Academic Search

Boron-doped diamond films were synthesized on an iridium substrate by microwave plasma-assisted chemical vapor deposition, using trimethylboron as the dopant source. The Ir substrate was bias-treated by the constant-current mode to permit the formation of oriented diamond nuclei. In order to isolate the B-doped diamond layer electrically from the Ir substrate, the non-doped diamond particles that were formed were grown

Katsuki Kusakabe; Akira Sobana; Ken-Ichiro Sotowa; Toshihiko Imato; Toshiki Tsubota

2003-01-01

361

Synthesis and structural study of nano\\/micro diamond overlayer films  

Microsoft Academic Search

The nano\\/micro diamond overlayer films have been successfully fabricated by means of bias growth technique using microwave plasma-enhanced chemical vapor deposition method. During the diamond growth, as a negative bias (?100V) is applied midway on the substrate side, the nanocrystalline diamond layer can be controllably deposited on the as-grown microcrystalline diamond to form a nano\\/micro overlayer structure. Transmission electron microscopy

N. Jiang; K Sugimoto; K Nishimura; Y Shintani; A Hiraki

2002-01-01

362

Protein-modified nanocrystalline diamond thin films for biosensor applications  

NASA Astrophysics Data System (ADS)

Diamond exhibits several special properties, for example good biocompatibility and a large electrochemical potential window, that make it particularly suitable for biofunctionalization and biosensing. Here we show that proteins can be attached covalently to nanocrystalline diamond thin films. Moreover, we show that, although the biomolecules are immobilized at the surface, they are still fully functional and active. Hydrogen-terminated nanocrystalline diamond films were modified by using a photochemical process to generate a surface layer of amino groups, to which proteins were covalently attached. We used green fluorescent protein to reveal the successful coupling directly. After functionalization of nanocrystalline diamond electrodes with the enzyme catalase, a direct electron transfer between the enzyme's redox centre and the diamond electrode was detected. Moreover, the modified electrode was found to be sensitive to hydrogen peroxide. Because of its dual role as a substrate for biofunctionalization and as an electrode, nanocrystalline diamond is a very promising candidate for future biosensor applications.

Härtl, Andreas; Schmich, Evelyn; Garrido, Jose A.; Hernando, Jorge; Catharino, Silvia C. R.; Walter, Stefan; Feulner, Peter; Kromka, Alexander; Steinmüller, Doris; Stutzmann, Martin

2004-10-01

363

HPHT preparation and Micro-Raman characterization of polycrystalline diamond compact with low residual stress  

NASA Astrophysics Data System (ADS)

High quality grown polycrystalline diamond compact (PDC) with low residual stress was prepared using the infiltration method with nickel based alloys as the solvent under high temperature and high pressure (HPHT). Scanning electron microscopy (SEM) was used to observe the micro morphology of the diamond layer and the diamond/WC substrate interface. It was found that dense and interlaced microstructure with diamond-diamond (D-D) direct bonding formed in the diamond layer of PDC. Micro-Raman spectroscopy was used to measure the Raman shift of diamonds in the polycrystalline diamond (PCD) layer and the residual stress was calculated based on the Raman shift of diamonds. Experimental results show that the residual stress of PCD layer is compressive stress, and the range of the residual stress is from 0.075 to 0.250 GPa in the whole PCD layer, much lower than that of other reports (up to 1.400 GPa). Moreover, the distribution of the residual stress from the diamond surface layer to the inner cross-section is homogeneous.

Jia, Hongsheng; Ma, Hongan; Guo, Wei; Jia, Xiaopeng

2010-08-01

364

Low-temperature growth of nanostructured diamond films.  

PubMed

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 degrees C) for 30 min using a H2/CH4/N2 gas mixture to grow a thin (approximately 600 nm) nanostructured diamond layer and to improve film adhesion. The remainder of the deposition involves growth at low temperature (< 600 degrees C) in a H2/CH4/O2 gas mixture. The continuation of the smooth nanostructured diamond film growth during low-temperature deposition is confirmed by in situ laser reflectance interferometry, atomic force microscopy, micro-Raman spectroscopy, and surface profilometry. Similar experiments performed without the initial 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. PMID:12914027

Baker, P A; Catledge, S A; Vohra, Y K

2001-03-01

365

layer  

Microsoft Academic Search

This paper analyzes the propagation of a cohesive crack through a reinforcement layer and gives a solution that can be used for any specimen and loading condition. Here it faces the case of a reinforced prismatic beam loaded at three points. Reinforcement is represented by means of a free-slip bar bridging the cracked section, anchored at both sides of the

Gonzalo Ruiz

366

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

367

Diamond tool machining of materials which react with diamond  

DOEpatents

This invention is comprised of an 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, R.L.; Stewart, D.D.; Evans, C.J.

1991-04-01

368

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

369

On the role of carbon radical insertion reactions in the growth of diamond by chemical vapor deposition methods.  

PubMed

Potential energy profiles for the insertion of gas phase C atoms, and CH, CH(2), C(2), C(2)H, and C(3) radicals, into C-H and C-C bonds on a 2 x 1 reconstructed, H-terminated diamond {100} surface have been explored using both quantum mechanical (density functional theory) and hybrid quantum mechanical/molecular mechanical (QM/MM) methods. Both sets of calculations return minimum energy pathways for inserting a C atom, or a CH(X), C(2)(X), or CH(2)(a) radical into a surface C-H bond that are essentially barrierless, whereas the barriers to inserting any of the investigated species into a surface C-C bond are prohibitively large. Reactivity at the diamond surface thus parallels behavior noted previously with alkanes, whereby reactant species that present both a filled sigma orbital and an empty p(pi) orbital insert readily into C-H bonds. Most carbon atoms on the growing diamond surface under typical chemical vapor deposition conditions are H-terminated. The present calculations thus suggest that insertion reactions, particularly reactions involving C((3)P) atoms, could make a significant contribution to the renucleation and growth of ultrananocrystalline diamond (UNCD) films. PMID:19778025

Richley, James C; Harvey, Jeremy N; Ashfold, Michael N R

2009-10-22

370

Bias-enhanced nucleation and growth processes for improving the electron field emission properties of diamond films  

NASA Astrophysics Data System (ADS)

The evolution of diamond films in bias-enhanced-nucleation (BEN) and bias-enhanced-growth (BEG) processes was systematically investigated. While the BEN process can efficiently form diamond nuclei on the Si substrates, BEG with large enough applied field (> -400 V) and for sufficiently long periods (>60 min) was needed to develop proper granular structure for the diamond films so as to enhance the electron field emission (EFE) properties of the films. For the films BEG under -400 V for 60 min (after BEN for 10 min), the EFE process can be turned on at a field as small as 3.6 V/?m, attaining a EFE current density as large as 325 ?A/cm2 at an applied field of 15 V/?m. Such an EFE behavior is even better than that of the ultrananocrystalline diamond films grown in CH4/Ar plasma. Transmission electron microscopic examination reveals that the prime factor enhancing the EFE properties of these films is the induction of the nano-graphite filaments along the thickness of the films that facilitates the transport of electrons through the films.

Teng, Kuang-Yau; Chen, Huang-Chin; Tzeng, Gaung-Chin; Tang, Chen-Yau; Cheng, Hsiu-Fung; Lin, I.-Nan

2012-03-01

371

Boron-Doped Nanocrystalline Diamond.  

National Technical Information Service (NTIS)

A conductive boron doped nanocrystalline diamond is described. The boron doped diamond has a conductivity which uses the boron in the crystals as a charge carrier. The diamond is particularly useful for electrochemical electrodes in oxidation-reduction re...

G. M. Swain M. Witek P. Sonthalia Y. Show

2004-01-01

372

O-terminated nano-diamond ISFET for applications in harsh environment  

Microsoft Academic Search

The concept of an ion-sensitive FET (ISFET) on diamond with boron delta-doped channel and oxygen-terminated surface for pH sensing has been successfully transferred to large-area nano-crystalline diamond on silicon substrates. The nano-crystalline diamond layers, including the boron delta-doped channels of the FETs, were grown by hot-filament CVD. The fabricated layers were characterised by their peak concentration of boron of 3×1020

M. Dipalo; C. Pietzka; A. Denisenko; H. El-Hajj; E. Kohn

2008-01-01

373

Characterisation of CVD grown diamond and its residual stress state  

Microsoft Academic Search

One of the most important quality factors in the judgement of thin diamond layers is the adhesion between the substrate and the layer which is limited by the residual stress state. The main reason for residual stress in coatings is the misfit in various properties of the layer and also the substrate, e.g. thermal expansion and crystal lattice type. The

M. Hempel; M. Härting

1999-01-01

374

Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants  

PubMed Central

With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD) coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD) layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD) and validate the multilayer coating’s effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios.

Booth, Leigh; Catledge, Shane A.; Nolen, Dustin; Thompson, Raymond G.; Vohra, Yogesh K.

2011-01-01

375

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

376

Boron-deuterium complexes in diamond: How inhomogeneity leads to incorrect carrier type identification  

Microsoft Academic Search

The electrical properties of boron doped diamond layers after deuterium diffusion have been investigated by Hall effect and capacitance voltage measurements. It is found that (i) the deuterated boron doped diamond layers are inhomogeneous after the deuterium diffusion, resulting in conducting and insulating areas; (ii) negative and positive Hall voltages are measured on the same boron doped sample after deuterium

A. Kumar; J. Pernot; P. Muret; A. Traore´; L. Magaud; A. Deneuville; N. Habka; J. Barjon; F. Jomard; M. A. Pinault; J. Chevallier; C. Mer-Calfati; J. C. Arnault; P. Bergonzo

2011-01-01

377

Superconductivity in diamond  

NASA Astrophysics Data System (ADS)

Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature Tc ~ 4K superconductivity survives in a magnetic field up to Hc2(0) >= 3.5T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.

Ekimov, E. A.; Sidorov, V. A.; Bauer, E. D.; Mel'nik, N. N.; Curro, N. J.; Thompson, J. D.; Stishov, S. M.

2004-04-01

378

Ozonolysis of diamond  

Microsoft Academic Search

The oxidation of diamond is attracting increasing interest, in the light of efforts to modulate its electronic properties for device applications. Ozone is a promising candidate oxidant species, allowing low temperature processing compared with molecular dioxygen. Here, we present first-principles molecular dynamics simulations for the dissociative adsorption of ozone on the {001} surface of diamond, carried out at the level

Christian K. Fink; Stephen J. Jenkins

2009-01-01

379

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

380

Superconductivity in diamond.  

PubMed

Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature T(c) approximately 4 K; superconductivity survives in a magnetic field up to Hc2(0) > or = 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions. PMID:15057827

Ekimov, E A; Sidorov, V A; Bauer, E D; Mel'nik, N N; Curro, N J; Thompson, J D; Stishov, S M

2004-04-01

381

Interactions of diamond surfaces with fusion relevant plasmas  

NASA Astrophysics Data System (ADS)

The outstanding thermal properties of diamond and its low reactivity towards hydrogen may make it an attractive plasma-facing material for fusion and calls for a proper evaluation of its behaviour under exposure to fusion-relevant plasma conditions. Micro and nanocrystalline diamond layers, deposited on Mo and Si substrates by hot filament chemical vapour deposition (CVD), have been exposed both in tokamaks and in linear plasma devices to measure the erosion rate of diamond and study the modification of the surface properties induced by particle bombardment. Experiments in Pilot-PSI and PISCES-B have shown that the sputtering yield of diamond (both physical and chemical) was a factor of 2 lower than that of graphite. Exposure to detached plasma conditions in the DIII-D tokamak have evidenced a strong resistance of diamond against erosion under those conditions.

De Temmerman, G.; Doerner, R. P.; John, P.; Lisgo, S.; Litnovsky, A.; Marot, L.; Porro, S.; Petersson, P.; Rubel, M.; Rudakov, D. L.; Van Rooij, G.; Westerhout, J.; Wilson, J. I. B.

2009-12-01

382

Mechanism for direct conversion of graphite to diamond  

NASA Astrophysics Data System (ADS)

The atomistic mechanism for direct conversion of graphite to diamond is a long-standing problem in condensed matter physics. Here, we establish by ab initio calculations bond reconstruction pathways from graphite to a basic series of diamond polytypes of 2H, 3C, 4H, and 12R. The conversion proceeds through two newly identified compressed-graphite phases of orthorhombic and monoclinic carbon with odd-membered (5 + 7) rings toward the diamond structures via a local-bond-rotation mechanism. The rhombohedral 12R phase represents a new crystal form of diamond with an alternating four-layered hexagonal (h) and cubic (c) close-packed structure in (hcch)3 stacking. These results resolve the fundamental questions about the graphite-to-diamond phase transformation at high pressure and high temperature.

Wang, Jian-Tao; Chen, Changfeng; Kawazoe, Yoshiyuki

2011-07-01

383

Diamond and diamond-like carbon films for advanced electronic applications  

SciTech Connect

Aim of this laboratory-directed research and development (LDRD) project was to develop diamond and/or diamond-like carbon (DLC) films for electronic applications. Quality of diamond and DLC films grown by chemical vapor deposition (CVD) is not adequate for electronic applications. Nucleation of diamond grains during growth typically results in coarse films that must be very thick in order to be physically continuous. DLC films grown by CVD are heavily hydrogenated and are stable to temperatures {le} 400{degrees}C. However, diamond and DLC`s exceptional electronic properties make them candidates for integration into a variety of microelectronic structures. This work studied new techniques for the growth of both materials. Template layers have been developed for the growth of CVD diamond films resulting in a significantly higher nucleation density on unscratched or unprepared Si surfaces. Hydrogen-free DLC with temperature stability {le} 800{degrees}C has been developed using energetic growth methods such as high-energy pulsed-laser deposition. Applications with the largest system impact include electron-emitting materials for flat-panel displays, dielectrics for interconnects, diffusion barriers, encapsulants, and nonvolatile memories, and tribological coatings that reduce wear and friction in integrated micro-electro-mechanical devices.

Siegal, M.P.; Friedmann, T.A.; Sullivan, J.P. [and others

1996-03-01

384

Isotopically Enriched C-13 Diamond Anvil as a Stress Sensor in High Pressure Experiments  

NASA Astrophysics Data System (ADS)

The conventional high pressure diamond anvils were modified by growing an isotopically pure C-13 diamond layer by microwave plasma chemical vapor deposition using methane/hydrogen/oxygen chemistry. The isotopically pure C-13 nature of the culet of the diamond anvil was confirmed by the Raman spectroscopy measurements. This isotopically engineered diamond anvil was used against a natural abundance diamond anvil for high pressure experiments in a diamond anvil cell. Spatial resolved Raman spectroscopy was used to measure the stress induced shift in the C-13 layer as well as the undelying C-12 layer to ultra high pressures. The observed shift and splitiing of the diamond first order Raman spectrum was correlated with the stress distribution in the diamond anvil cell. The experimental results will be compared with the finite element modeling results using NIKE-2D software in order to create a mathematical relationship between sets of the following parameters: vertical (z axis) distance; horizontal (r axis) distance; max shear stress, and pressure. The isotopically enriched diamond anvils offer unique opportunities to measure stress distribution in the diamond anvil cell devices.

Vohra, Yogesh; Qiu, Wei; Kondratyev, Andreiy; Velisavljevic, Nenad; Baker, Paul

2004-03-01

385

Carbon dimers on the diamond (100) surface:??Growth and nucleation  

NASA Astrophysics Data System (ADS)

We use a density-functional based tight-binding method to study diamond growth by C2 on a nonhydrogenated diamond (100)-(2×1) surface. The study is motivated by advances in the growth of ultrananocrystalline diamond (UNCD) films under hydrogen-poor conditions. We identify and classify stable adsorbate configurations formed above dimer rows and troughs on the reconstructed surface. We also investigate adsorption and migration barriers using the nudged elastic band method. We find viable adsorption pathways leading to chain growth and step advancement. Initial depositions proceed without barriers into topologically imperfect configurations. The most stable configuration is a growth position that bridges two adjacent surface dimers along a dimer row. It is reached over a barrier of 1.2 eV and has an adsorption energy of -6.9 eV. Many other configurations exist that have adsorption energies differing by up to 2.7 eV. By comparison, analogous structures for silicon are fewer in number and closer in energy because Si lacks ? bonding, which is important for C2 on diamond. Migration barriers for ad-dimers are in the range of 2 3 eV due to relatively large differences in the energies of intermediate local minima. Comparing our results with previous studies on the (110) surface, we note that barriers leading to growth are higher and pathways are more complex on the (100) surface. The barriers suggest that reactions leading to both growth and re-nucleation are possible, which helps to understand the small observed grain sizes in UNCD.

Sternberg, Michael; Zapol, Peter; Curtiss, Larry A.

2003-11-01

386

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.

1999-07-01

387

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

388

Instrumentation development for electrical conductivity imaging in polycrystalline diamond cutters  

NASA Astrophysics Data System (ADS)

We previously reported on an electrical conductivity non-destructive inspection methodology for polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. We use electrical impedance tomography to image the conductivity in the diamond table. In this paper we report on progress in preparing this instrument for factory deployment. Instrument enhancements include an adjustable part holder, a field-swappable sensor and GPU-enabled software capable of rapidly acquiring images.

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

2013-01-01

389

Laser CVD of diamond  

SciTech Connect

An experimental study of diamond formation by laser-induced chemical vapor deposition of a gaseous mixture of CH{sub 4} and H{sub 2}. A carbon aerosol is used to induce laser breakdown. The laser used in this work is an ND:YAG laser which emits 0--70 mJ/pulses with 10 Hz pulse duration. The laser will act as a virtual filament allowing for the deposition of diamond on a substrate. The authors attempt to deposit other material, such as WC, along with diamond.

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

1995-04-01

390

Diamond at 800 GPa  

SciTech Connect

A new compression technique, which enables the study of solids into the TPa regime, is described and used to ramp (or quasi-isentropically) compress diamond to a peak pressure of 1400 GPa. Diamond stress versus density data are reported to 800 GPa and suggest that the diamond phase is stable and has significant material strength up to at least this stress level. Data presented here are the highest ramp compression pressures by more than a factor of 5 and the highest-pressure solid equation-of-state data ever reported.

Bradley, D. K.; Eggert, J. H.; Smith, R. F.; Prisbrey, S. T.; Hicks, D. G.; Braun, D. G.; Biener, J.; Hamza, A. V.; Rudd, R. E.; Collins, G. W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

2009-02-20

391

Boron acceptor concentration in diamond from excitonic recombination intensities  

Microsoft Academic Search

Excitonic recombinations are investigated by cathodoluminescence in a series of homoepitaxial diamond layers doped with boron in the range (2×1016)-(5×1018)atcm-3. As opposed to earlier observations made on polycrystalline boron-doped diamond, we show that the ratio between the neutral-boron bound exciton and the free-exciton recombination intensities is proportional to the boron content up to 6×1017cm-3 and starts to saturate above this

J. Barjon; T. Tillocher; N. Habka; O. Brinza; J. Achard; R. Issaoui; F. Silva; C. Mer; P. Bergonzo

2011-01-01

392

Residual stress and stress gradients in polycrystalline diamond compacts  

Microsoft Academic Search

Thermal residual macrostresses and their gradients were studied in a series of polycrystalline diamond compacts (PDC) using neutron diffraction. The specimens comprised WC–Co cemented carbides with high temperature\\/high pressure (HTHP) sintered polycrystalline diamond (PCD) layers. Residual stresses were investigated in two as-sintered variants and after several post-sinter thermal treatments and bonding processes. Measurements were made of (1) the average in-plane

J. W Paggett; E. F Drake; A. D Krawitz; R. A Winholtz; N. D Griffin

2002-01-01

393

Polycrystalline Diamond and Boron Nitride Cutting Tools.  

National Technical Information Service (NTIS)

The problems of diamond synthesis and the problems of bonding diamond are intimately related. No one has ever succeeded in achieving a decent polycrystalline diamond compact, bonded outside of the stability field of diamond. Further, all bonding not only ...

1976-01-01

394

31 CFR 592.310 - Rough diamond.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 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...

2010-07-01

395

31 CFR 592.310 - Rough diamond.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 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...

2009-07-01

396

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

397

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

398

PROCESS FOR COLORING DIAMONDS  

DOEpatents

A process is given for coloring substantially colorless diamonds in the blue to blue-green range and comprises the steps of irradiating the colorless diamonds with electrons having an energy within the range 0.5 to 2 Mev to obtain an integrated electron flux of between 1 and 2 x 10/sup 18/ thc diamonds may be irradiated 1 hr when they take on a blue color with a slight green tint: After being heated at about 500 deg C for half an hour they become pure blue. Electrons within this energy range contam sufficient energy to displace the diamond atoms from their normal lattice sites into interstitial sites, thereby causing the color changes.

Dugdale, R.A.

1960-07-19

399

Characterization of ZnO\\/diamond SAW devices elaborated on the smooth nucleation side of MPACVD diamond  

Microsoft Academic Search

We designed a SAW filter in this work by combining the piezoelectric ZnO film with a freestanding double layer diamond film deposited using CH4-H2 pulsed MPACVD process through two growth stages. The AFM measurements on the nucleation side of the diamond film has shown that this side is smooth enough to perform photolithography process in the SAW device elaboration, while

L. Le Brizoual; T. Lamara; F. Sarry; M. Belmahi; O. Elmazria; J. Bougdira; M. Remy; P. Alnot

2005-01-01

400

Ekati Diamond Mine  

NSDL National Science Digital Library

The page on the Ekati Diamond Mine, which is located in the Northwest Territories and is North America's only operating diamond mine, presents a satellite image and informational text. A detailed map of the region is also included which will allow users to compare the satellite image to what the area looks like on a map. The CCRS was last mentioned in the May 24, 2000 Scout Report for Science and engineering.

2001-01-01

401

HPHT preparation and Micro-Raman characterization of polycrystalline diamond compact with low residual stress  

Microsoft Academic Search

High quality grown polycrystalline diamond compact (PDC) with low residual stress was prepared using the infiltration method\\u000a with nickel based alloys as the solvent under high temperature and high pressure (HPHT). Scanning electron microscopy (SEM)\\u000a was used to observe the micro morphology of the diamond layer and the diamond\\/WC substrate interface. It was found that dense\\u000a and interlaced microstructure with

Hongsheng Jia; Hongan Ma; Wei Guo; Xiaopeng Jia

2010-01-01

402

Influence of Bias-Enhanced Nucleation on Thermal Conductance Through Chemical Vapor Deposited Diamond Films  

Microsoft Academic Search

This work describes an experimental study of the cross-plane thermal conductance of plasma-enhanced chemical vapor deposited (PECVD) diamond films grown as a result of bias-enhanced nucleation (BEN). The diamond films are grown on silicon wafers using a two-step process in which a nucleation layer of amorphous or diamond like (DLC) carbon is first deposited on the silicon under the influence

Baratunde A. Cola; Ratnakar Karru; Changrui Cheng; Xianfan Xu; Timothy S. Fisher

2008-01-01

403

Gas Sensing Interactions at Hydrogenated Diamond Surfaces  

Microsoft Academic Search

Hydrogenated diamond (HD) samples exhibit a p-type surface conductivity (SC) which is caused by transfer doping to an adsorbed liquid electrolyte layer. We report on gas sensing experiments showing that such samples selectively respond to NO2 and NH3 gases at room temperature. Successive substitution of H-terminated surface sites by O-termination ones causes an increase in both the sensor baseline resistance

Andreas Helwig; Gerhard Muller; Olaf Weidemann; Andreas Hartl; Jose Antonio Garrido; Martin Eickhoff

2007-01-01

404

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

2012-05-01

405

FTIR Spectra of faceted diamonds and diamond simulants  

Microsoft Academic Search

FTIR spectra of faceted diamonds and diamond simulants collected by diffuse reflectance, transflectance, and specular reflection techniques were compared. The transflectance technique exploited total internal reflection phenomenon within the faceted diamond for the spectral acquisition. The transflectance spectra were similar to the well-accepted diffuse reflectance spectra with equal or better spectral qualities. Based on the observed spectral features of the

Pimthong Thongnopkun; Sanong Ekgasit

2005-01-01

406

Shock Diamonds and Mach Disks  

NSDL National Science Digital Library

The article presents and explains the diamond-shaped pattern that appears in the rocket engine and jet engine exhausts. Several photographs illustrate this phenomenon, and images show how crisscrossing shock waves produce the diamond shapes.

2010-06-03

407

Facts about Diamond Blackfan Anemia  

MedlinePLUS

... message, please visit this page: About CDC.gov . Diamond Blackfan Anemia (DBA) Share Compartir Add this to... ... Favorites Delicious Digg Google Bookmarks Facts About DBA Diamond Blackfan anemia (DBA) is a rare blood disorder ...

408

Diamond Turning Machine Design Overview.  

National Technical Information Service (NTIS)

Ultraprecision, single-point diamond tool machining is a rapidly developing technology that is able to provide cost-effective optical reflectors. These diamond-turning machines utilize conventional machine-tool-design concepts. However, additional attenti...

W. E. Barkman P. J. Steger

1978-01-01

409

Finishing Tubular Diamond Turned Optics.  

National Technical Information Service (NTIS)

Single Point Diamond Turning can produce adequate accuracy in figure and roundness for most x-ray grazing incidence optics. It cannot produce adequate smoothness, necessitating that the metallic optics be diamond-polished using the method described in thi...

N. J. Brown B. A. Fuchs

1986-01-01

410

Utilizing of hydrocarbon contamination for prevention of the surface charge-up at electron-beam assisted chemical etching of a diamond chip  

NASA Astrophysics Data System (ADS)

Electron beam assisted chemical etching (EBACE) with oxygen gas is not applicable for direct fine patterning of diamond devices, because the diamond is an electrical insulator and electron beam impingement of the diamond causes the surface charge-up. It is possible to form conductive layer of hydrocarbon on the diamond surface by electron beam irradiation in the atmosphere of diffusion pump oil vapors. In this paper, a scanning electron microscope (SEM) combined with oxygen gas introduction system was used for EBACE of the diamond. It was found by in-situ SEM observation that rectangular patterns with several ?m2 area and sub-?m depth were formed on the diamond chip.

Taniguchi, J.; Miyamoto, I.; Ohno, N.; Honda, S.

1997-01-01

411

Characterization of ZnO/diamond SAW devices elaborated on the smooth nucleation side of MPACVD diamond  

NASA Astrophysics Data System (ADS)

We designed a SAW filter in this work by combining the piezoelectric ZnO film with a freestanding double layer diamond film deposited using CH4-H2 pulsed MPACVD process through two growth stages. The AFM measurements on the nucleation side of the diamond film has shown that this side is smooth enough to perform photolithography process in the SAW device elaboration, while the good quality of the diamond film produced on this side has been confirmed through Raman spectroscopy.Furthermore, the ZnO films having their c axis perpendicular to the substrate were deposited using reactive magnetron sputtering under the optimal experimental conditions found from XRD measurements. In the SAW device elaboration on this ZnO/bilayer diamond structure, aluminium interdigital transducers (IDTs) were developed by conventional contact UV photolithography on the nucleation side of the freestanding diamond. The frequency response of the device presents harmonics of the acoustic wave modes propagating in the smooth diamond nucleation side. The good agreement obtained between the experimental and theoretical frequency responses attests that the elastic properties of the ZnO and the diamond are similar to those of the single crystal assumed in the theoretical study.

Le Brizoual, L.; Lamara, T.; Sarry, F.; Belmahi, M.; Elmazria, O.; Bougdira, J.; Remy, M.; Alnot, P.

2005-09-01

412

Processing of functionally graded tungsten carbide-cobalt-diamond composites  

NASA Astrophysics Data System (ADS)

Polycrystalline diamond compacts (PDCs) are widely used as drill bit cutters in rock drilling and as tool bits in machining non-ferrous materials. A typical PDC comprises a thin layer of sintered polycrystalline diamond bonded to a tungsten carbide-cobalt substrate. A well recognized failure mechanism is delamination at the interface between diamond and cemented carbide. High stresses at the diamond/carbide interface, due to thermal expansion and modulus mismatch, are the primary cause of in-service failure under impact loading conditions. This work was undertaken to develop a tungsten carbide-cobalt-diamond composite, which has a continuously graded interface between the diamond and tungsten carbide. The process developed comprised the following steps: (i) generation of a pore size gradient by electrochemical etching of cobalt from the surface of a partially sintered tungsten carbide-cobalt preform; (ii) chemical vapor infiltration of the porous preform with carbon by catalytic decomposition of a methane/hydrogen mixture, resulting in a graded carbon concentration; and (iii) consolidation of the carbon infiltrated preforms at 8GPa/1500°C to complete densification and to transform the carbon into diamond. Thus, the final product consists of a functionally graded WC-Co-diamond composite, with controlled distribution of the constituent phases. Tungsten carbide-cobalt powders with mean tungsten carbide particle size of 0.8mum(micro-grain) and 100 nm(nano-grain) were used as starting materials. Processing conditions were adjusted to obtain an optimal distribution of carbon in porous preforms. After high pressure/high temperature consolidation, both micro- and nano-composites showed a diffused interface between inner and outer regions of the fully dense materials. A micro-composite showed columnar-like tungsten carbide grains and faceted diamond grains in the outer region of the sintered material. The grain size of the diamond in this region was ˜2mum, and the hardness was VHN = 3700 +/- 60 kg/mm2. The inner region showed equiaxed tungsten carbide grains, with some grains having a coating of diamond-like carbon. A nano-composite showed equiaxed tungsten carbide grains and faceted diamond grains in the outer region of the sintered material. The grain size for both tungsten carbide and diamond was ˜200nm, and the hardness was VHN = 3186 +/- 300 kg/mm2.

Jain, Mohit

413

Diamond deposition on noble metals  

Microsoft Academic Search

Diamond was deposited by the hot-filament method on foils of Pt, Pd and Au. These metals are characterized by different solubility for carbon and hydrogen, and the substrate thickness is also an important factor for diamond nucleation because of the carbon solubility. Nucleation and growth of diamond Pt, Pd and Au was studied systematically using different foil thickness of the

W. Kalss; R. Haubner; B. Lux

1997-01-01

414

POLYCRYSTALLINE DIAMOND COMPACT BIT HYDRAULICS  

Microsoft Academic Search

It is well understood and documented that bottomhole hydraulics plays an important role in conventional diamond bit performance. Recent industry experience has shown a similar importance with the new synthetic diamond compact bits. Certain types of polycrystalline diamond compact bits have cutters arranged in a reverse spiral mode. For optimum performance bit hydraulic design should be tailored to that reverse

R. H. Knowlton; Hsin Huang; B. Iversen

1982-01-01

415

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

416

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

417

Magnetic properties of polycrystalline diamonds  

Microsoft Academic Search

The remanent magnetism and bulk magnetic properties of polycrystalline diamonds have been investigated. The diamonds are of two distinct types, those occurring together with gem-grade diamonds in kimberlite pipes in S Africa, and carbonados, found in placer deposits notably in Brazil and the Central African Republic. Both types generally possess measurable remanent magnetization, the former stronger than the latter, and

D. W. Collinson

1998-01-01

418

Raman barometry of diamond formation  

Microsoft Academic Search

Pressures and temperatures of the diamond source region are commonly estimated using chemical equilibria between coexisting mineral inclusions. Here we present another type of geobarometer, based on determination of the internal pressure in olivine inclusions and the stresses in the surrounding diamond. Using Raman spectroscopy, pressures of 0.13 to 0.65 GPa were measured inside olivine inclusions in three diamonds from

E. S. Izraeli; J. W. Harris; O. Navon

1999-01-01

419

Semirigid sets of diamond orders  

Microsoft Academic Search

An order relation ?ab on a set A is a diamond provided x ?aby holds exactly if x = a or y = b. A set R of diamonds on A is semirigid if the identity map on A and all constant self-maps of A are the only self-maps of A that are (jointly) isotone for all diamonds from R.

Vaktang Lashkia; Masahiro Miyakawa; Akihiro Nozaki; Grant Pogosyan; Ivo G. Rosenberg

1996-01-01

420

Electrochemistry of Diamond: A Review  

Microsoft Academic Search

Because of its extraordinary chemical stability, diamond is a perspective electrode material to be used in electrochemistry and electrochemical engineering. In this review-article, the results of basic studies in the synthetic-diamond electrochemistry are summarized: the electrochemical kinetics, photoelectrochemistry, electrochemical impedance spectroscopy. Relations between the semiconductor nature and crystal structure of diamond and its electrochemical behavior are revealed. Prospects for using

Yu. V. Pleskov

2002-01-01

421

Ohmic contacts to semiconducting diamond using a Ti\\/Pt\\/Au trilayer metallization scheme  

Microsoft Academic Search

Ohmic contacts have been fabricated on a naturally occurring type IIb diamond crystal using an annealed Ti\\/Pt\\/Au trilayer metallization where the Pt served successfully as a barrier to Ti diffusion into the Au capping layer. However, a specific contact resistance could not be reliably determined using transmission line model measurements. Auger microanalysis revealed the presence of Ti on the diamond

H. A. Hoff; G. L. Waytena; C. L. Vold; J. S. Suehle; I. P. Isaacson; M. L. Rebbert; D. I. Ma; K. Harris

1996-01-01

422

Laser patterning of diamond. Part II. Surface nondiamond carbon formation and its removal  

NASA Astrophysics Data System (ADS)

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 ~60 nm. Ozone cleaning was used to remove the nondiamond carbon layer.

Smedley, John; Jaye, Cherno; Bohon, Jen; Rao, Triveni; Fischer, Daniel A.

2009-06-01

423

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

424

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.

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

2010-01-01

425

Diamond membrane surface after ion-implantation-induced graphitization for graphite removal: Molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

Fabrication of diamond membranes, wherein photonic crystals and other nanosized optical devices can be realized, is of great importance. Many spintronic devices are based on specific optically active atomic structures in diamond, such as the nitrogen-vacancy center, and rely on the membrane’s performance. One promising approach for realizing such membranes is by creating a heavily damaged layer (rich in broken bonds) in diamond by ion implantation. Following annealing, this layer converts to graphite, which can be chemically removed, leaving a free-standing diamond membrane. Unfortunately, the optical properties of the exposed diamond surface (the diamond-vacuum interface) of such membranes currently are insufficient for high-quality photonic devices. We present molecular dynamics studies of the atomic structure of the etchable graphite/diamond interface. Different implantation and annealing conditions are simulated. The results show that cold implantation, followed by high-temperature annealing (>1500°C) leads to the creation of the sharpest diamond-etchable graphite interface, which should exhibit optimal optical properties among diamond membranes created by the implantation/graphitization method.

Silverman, Amihai; Adler, Joan; Kalish, Rafi

2011-06-01

426

Photo-stimulated low electron temperature high current diamond film field emission cathode  

DOEpatents

An electron source includes a back contact surface having a means for attaching a power source to the back contact surface. The electron source also includes a layer comprising platinum in direct contact with the back contact surface, a composite layer of single-walled carbon nanotubes embedded in platinum in direct contact with the layer comprising platinum. The electron source also includes a nanocrystalline diamond layer in direct contact with the composite layer. The nanocrystalline diamond layer is doped with boron. A portion of the back contact surface is removed to reveal the underlying platinum. The electron source is contained in an evacuable container.

Shurter; Roger Philips (Los Alamos, NM), Devlin; David James (Santa Fe, NM), Moody; Nathan Andrew (Los Alamos, NM), Taccetti; Jose Martin (Santa Fe, NM), Russell; Steven John (Los Alamos, NM)

2012-07-24

427

Topomineralogy of the Siberian diamonds  

NASA Astrophysics Data System (ADS)

Diamond placers are widespread in the modern alluvial deposits and ancient sedimentary collectors of the Siberian craton and can be divided into two major types: 1) related with the rich and famous kimberlites such as Mir and International pipe and 2) with unidentified root source. The lattert are wide spread, industrially significant and in use in the north-east of the Siberian craton. Yet, kimberlites known in the north-east of the Siberian craton have poor diamond concentrations or non-diamondiferous at all. A contradiction occur between high alluvial and extremely-low host diamond content of this region. Detailed studies of this problem led to the fact that diamonds from the alluvial deposits of the Siberian craton, as well as other diamondiferous regions, show broader spectrum of typomorphic features than diamonds from the known kimberlites. Moreover, some diamond groups are not typical for the phanerozoic kimberlites of Siberia, or do not occur in significant amounts. The foregoing suggests that diamonds from the unknown host rock type occur in the diamond placers of the Siberian craton along with typical kimberlite diamonds. Based on the detailed studies of the typomorphic features of the alluvial diamonds from Siberian craton 5 parasteresis groups, probably related to different host rock types, were distinguished. Parasteresis is a regular spatial mineral association which are united by single geological process, such as kimberlite indicator minerals and diamonds from kimberlites which differ in genesis but united by the whole kimberlitic process. Parasteresis 1 (kimberlite-type) involves diamonds which are common for the phanerozoic kimberlites. Parasteresis 2 (supposed to be lamproitic) includes roundish (cryptolaminar) diamonds of dodecahedron habit, the so called "brazilian" or "ural" types. In Siberian phanerozoic industrial kimberlites the part of such diamonds does not exceed 15%. That is the diamonds which dominate in the placers of the Urals and nearby Eastern Sayan (south-west of the Siberian craton). Parasteresis 3 (unknown host rock type) includes yellow-orange cuboids (II type according to Orlov's classification), which occur in kimberlites in small quantities, but most common in the north-east placers of the Siberian craton. Parasteresis 4 (unknown host rock type) includes diamonds of V and VII types according to Orlov, which are entirely absent in kimberlites. Parasteresis 5 involves the so called yacutites - microcrystalline substance with the add of lonsdaleite phase, typical for diamonds from impact craters. Comparison of yacutites with diamonds from Popigay astrobleme showed up their complete similarity. This fact is evident for the relation of yacutites to the Popigay astrobleme. Thus, in the placers of the Siberian craton there are at least three groups of diamonds with the unknown host rock type. The distribution of the discriminated types of diamonds among the craton is higly uneven. Diamonds of 2,3,4 and 5 parasteresis type (supposed to be from lamprophyres, unknown sources and yacutites) predominate in the north-eastern placers of the Siberian craton, whereas the part of the kimberlitic diamonds is less then a half, in some areas they are completely absent. Early- carboniferous deposits of the Kjutungdinskij graben is the only area where kimberlitic diamonds strongly predominate. That was the case to predict mid-paleozoic kimberlitic field there. In the central part of the province the major role goes to the kimberlitic diamonds associated with the mid-paleozoic kimberlites. Roundish diamonds of the second parasteresis type are in lead on the south of the Siberian craton, and may probably associate with the lamprophyres such as Ingash complex. Mapping of distribution of the distinguished diamond parasteresises among the Siberian craton reveals the tendency of diamonds hypothetically from lamprophyres and unknown sources to associate with the precambrian protrusions - Anabar shield, Olenek rise and Eastern Sayan. This allows us to suggest that the diamonds supply of the

Afanasyev, Valentin; Lobanov, Sergey; Vasiliy, Koptil; Bogdan, Pomazanskiy; Alexander, Gerasimchuk; Nikolay, Pokhilenko

2010-05-01

428

Development of Designer Diamond Anvils for High Pressure-High-Temperature Experiments in Support of the Stockpile Stewardship Program  

SciTech Connect

The focus of this program at the University of Alabama at Birmingham (UAB) is to develop the next generation of designer diamond anvils that can perform simultaneous joule heating and temperature profile measurements in a diamond anvil cell. A series of tungsten-rhenium thermocouples will be fabricated onto to the anvil and encapsulated by a chemical vapor deposited diamond layer to allow for a complete temperature profile measurement across the anvil. The tip of the diamond anvil will be engineered to reduce the thermal conductivity so that the tungsten-heating coils can be deposited on top of this layer. Several different approaches will be investigated to engineer the tip of the diamond anvil for reduction in thermal conductivity (a) isotopic mixture of 12C and 13C in the diamond layer, (b) doping of diamond with impurities (nitrogen and/or boron), and (c) growing diamond in a higher concentration of methane in hydrogen plasma. Under this academic alliance with Lawrence Livermore National Laboratory (LLNL), PI and his graduate students will use the lithographic and diamond polishing facility at LLNL. This proposed next generation of designer diamond anvils will allow multi-tasking capability with the ability to measure electrical, magnetic, structural and thermal data on actinide materials with unparallel sensitivity in support of the stockpile stewardship program.

Yogesh K. Vohra

2005-05-12

429

DIAMOND AMPLIFIED PHOTOCATHODES.  

SciTech Connect

High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

2007-11-26

430

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

431

Diamond-Like Carbon Coatings as Encapsulants for Photovoltaic Solar Cells.  

National Technical Information Service (NTIS)

High-quality single-layer and bilayer diamond-like carbon (DLC) thin films are fabricated by two technologies, namely, ion-assisted plasma-enhanced deposition (IAPED) and electron cyclotron resonance (ECR) deposition. Deposition on various substrates, suc...

F. J. Pern K. Touryan Z. Panosyan A. A. Gippius J. A. Kontsevoy

2005-01-01

432

Boron ?-doped (111) diamond solution gate field effect transistors.  

PubMed

A solution gate field effect transistor (SGFET) using an oxidised boron ?-doped channel on (111) diamond is presented for the first time. Employing an optimised plasma chemical vapour deposition (PECVD) recipe to deposit ?-layers, SGFETs show improved current-voltage (I-V) characteristics in comparison to previous similar devices fabricated on (100) and polycrystalline diamond, where the device is shown to operate in the enhancement mode of operation, achieving channel pinch-off and drain-source current saturation within the electrochemical window of diamond. A maximum gain and transconductance of 3 and 200?S/mm are extracted, showing comparable figures of merit to hydrogen-based SGFET. The oxidised device shows a site-binding model pH sensitivity of 36 mV/pH, displaying fast temporal responses. Considering the biocompatibility of diamond towards cells, the device's highly mutable transistor characteristics, pH sensitivity and stability against anodic oxidation common to hydrogen terminated diamond SGFET, oxidised boron ?-doped diamond SGFETs show promise for the recording of action potentials from electrogenic cells. PMID:22317833

Edgington, Robert; Ruslinda, A Rahim; Sato, Syunsuke; Ishiyama, Yuichiro; Tsuge, Kyosuke; Ono, Tasuku; Kawarada, Hiroshi; Jackman, Richard B

2012-01-08

433

Interfacial study of cubic boron nitride films deposited on diamond.  

PubMed

We have studied the nucleation and growth of cubic boron nitride (cBN) films deposited on silicon and diamond-coated silicon substrates using fluorine-assisted chemical vapor deposition (CVD). These comparative studies substantiate that the incubation amorphous/turbostratic BN layers, essential for the cBN nucleation on silicon, are not vital precursors for cBN nucleation on diamond, and they are inherently eliminated. At vastly reduced critical bias voltage, down to -10 V, cBN growth is still maintained on diamond surfaces, and cBN and underlying diamond crystallites exhibit an epitaxial relationship. However, the epitaxial growth is associated with stress in the cBN-diamond interfacial region. In addition, some twinning of crystallites and small-angle grain boundaries are observed between the cBN and diamond crystallites because of the slight lattice mismatch of 1.36%. The small-angle grain boundaries could be eliminated by imposing a little higher bias voltage during the initial growth stage. The heteroepitaxial growth of cBN films on different substrate materials are discussed in the view of lattice matching, surface-energy compatibility, and stability of the substrate against ion irradiation. PMID:16853031

Zhang, W J; Meng, X M; Chan, C Y; Chan, K M; Wu, Y; Bello, I; Lee, S T

2005-08-25

434

ELECTRONIC-PROPERTIES OF SEMICONDUCTING DIAMOND-LIKE CARBON DIAMOND  

Microsoft Academic Search

Semiconducting diamond-like carbon diamond (DLC-diamond) films were deposited by r.f. plasma-enhanced chemical vapour deposition (PECVD) at room temperature. The source gas was a mixture of methane and argon and the substrates used were n type \\\\{100\\\\} silicon. The films are found to be semiconducting with a variable band gap from 1.2 to 4.0 eV which can be controlled by changing

KK CHAN; SRP SILVA; GAJ AMARATUNGA

1992-01-01

435

Depth profiling of fluorine-doped diamond-like carbon (F-DLC) film: Localized fluorine in the topmost thin layer can enhance the non-thrombogenic properties of F-DLC  

Microsoft Academic Search

Fluorine-doped diamond-like carbon (F-DLC) has recently drawn a great deal of attention as a more non-thrombogenic coating than conventional DLC for blood-contacting medical devices. We conducted quantitative depth profiling of F-DLC film by X-ray photoelectron spectroscopy (XPS) in order to elucidate the effects of fluorine and fluorine distribution in F-DLC film in connection with the prevention of surface blood adhesion.

Terumitsu Hasebe; S. Nagashima; Aki Kamijo; Taichi Yoshimura; Tetsuya Ishimaru; Yukihiro Yoshimoto; Satoshi Yohena; Hideyuki Kodama; Atsushi Hotta; Koki Takahashi; Tetsuya Suzuki

2007-01-01

436

Diamond Film Gas Sensors for Leak Detection of Semiconductor Doping Gases  

NASA Astrophysics Data System (ADS)

Gas sensors for leak detection of toxic semiconductor doping gases such as PH3, B2H6, and AsH3 were fabricated using diamond films. The sensors have a double-layered structure composed of undoped and B-doped polycrystalline diamond layers with Pt electrodes. The relative changes in the resistance of the sensors were typically 10-20% for 0.2 ppm PH3 in air, and the highest value was over 100%. It was concluded that the diamond film gas sensors fabricated in the present work would be practically applicable as compact solid-state sensors with an advantage over the conventional aqueous electrolyte sensors.

Hayashi, Kazushi; Yokota, Yoshihiro; Tachibana, Takeshi; Miyata, Koichi; Kobashi, Koji; Fukunaga, Tetsuya; Takada, Tadashi

2000-01-01