Defect and Raman Spectroscopy of Chemical Vapor Deposition Grown Diamond Films

1999 ◽  
Vol 558 ◽  
Author(s):  
J.M. Perez ◽  
R.E. Stallcup ◽  
I.A. Akwani
Keyword(s):  
Raman Spectroscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
High Efficiency ◽  
Incident Light ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Hydrogen Gas ◽  
Photoelectron Emission ◽  
Light Power

ABSTRACTUsing photoelectron emission and Raman spectroscopy, we characterize normally unoccupied states that have an energy 2.41-2.71 eV below the conduction band of polycrystalline diamond films. The films are grown using chemical vapor deposition with methane to hydrogen gas concentrations of 0.10%, 0.20%, 0.30%, 0.45%, 0.60% and 0.70%. Photoelectron emission is performed using visible light from an argon laser. The light is focussed on a 5-10 µm diameter area of the sample. The emitted electrons are collected with high efficiency using a microchannel plate detector. Raman spectroscopy is performed simultaneously with photoelectron emission to determine the morphology and diamond versus graphite content of the photoelectron emission area. The photoelectron emission rate is observed to have a quadratic dependence on the incident light power showing that the photoelectron emission process is a two-photon process involving the excitation of electrons from normally unoccupied states. The photoelectric yield versus incident photon energy, and the photoelectric yield as a function of methane concentration are presented.

Growth of Nanocrystalline Diamond Films on Co-Cemented Tungsten Carbide Substrates by Hot Filament CVD

2004 ◽  
Vol 471-472 ◽  
pp. 52-58 ◽  
Author(s):  
Fang Hong Sun ◽  
Zhi Ming Zhang ◽  
H.S. Shen ◽  
Ming Chen
Keyword(s):  
Electron Microscopy ◽  
Surface Roughness ◽  
Raman Spectroscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Nanocrystalline Diamond ◽  
Composite Diamond ◽  
Hot Filament

Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using CH4/H2/Ar gas mixture by hot filament chemical vapor deposition (HFCVD) technique. The evidence of nanocrystallinity, smoothness and purity was obtained by characterizing the sample with scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM) and selected-area electron diffraction (SAED). A new process was used to deposit composite diamond films by a two-step chemical vapor deposition procedure including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond. The results show that the film consists of nanocrystalline diamond grains with sizes range from 20 to 80 nm. The Raman spectroscopy, XRD pattern, HR-TEM image and SAED pattern of the films indicate the presence of nanocrystalline diamond. Surface roughness is measured as Ra<100nm by AFM. Smooth nanocrystalline diamond layers can be deposited on conventional microcrystalline diamond layers using a two-step chemical vapor deposition by regulating the deposition parameters. These composite diamond films with the multiplayer (nanocrystalline/microcrystalline) structure have low surface roughness and high adhesive strength on WC-Co substrates. The diamond-coated tools and drawing dies with these composite coatings display excellent performances in the practical application.

(110)-oriented diamond films synthesized by microwave chemical-vapor deposition

1990 ◽  
Vol 5 (11) ◽  
pp. 2469-2482 ◽  
Author(s):  
Koji Kobashi ◽  
Kozo Nishimura ◽  
Koichi Miyata ◽  
Kazuo Kumagai ◽  
Akimitsu Nakaue
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Microwave Plasma ◽  
Hydrogen Plasma ◽  
Diamond Films ◽  
Film Surface ◽  
Chemical Vapor ◽  
Hydrogen Gas ◽  
X Ray ◽  
Bilayer Films

Bilayer diamond films were deposited on Si substrates by microwave-plasma chemical-vapor deposition (CVD) using a methane-hydrogen gas mixture. The first layer was deposited for 3 h using a reaction gas which was composed of 2.5 vol. % methane and 97.5 vol.% hydrogen. The deposited film consisted of very weakly (110)-oriented microcrystalline diamonds as well as amorphous carbon and graphite. In order to remove non-diamond carbons from the film surface, the specimen was treated in hydrogen plasma for 1 h. Finally, a second layer was deposited on the first layer for 14 h using a methane concentration of between 0.2 and 1.6 vol.%. It was found that the x-ray intensity of the (220) diffraction of the bilayer films was much greater than that of the (111) diffraction, indicating that the diamond grains in the second layer were strongly oriented with their crystallographic (110) planes parallel to the substrate surface. X-ray diffraction spectra of bilayer films in which the second layer was deposited for 7, 14, 21, and 35 h using two different methane concentrations, 0.3 and 1.2 vol.%, showed that within periods of up to 21 h, the (220) intensity increased with the deposition time much more quickly than the (111) intensity, indicating that the degree of (110) orientation was further enhanced as the second layer thickness increased. However, the (220) intensity decreased after 21 h, presumably due to thermal randomization. Results of scanning electron microscopy, electron diffraction, and Raman spectroscopy of the bilayer films are also presented.

scholarly journals Facile integration of MoS2/SiC photodetector by direct chemical vapor deposition

Nanophotonics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 3035-3044 ◽  
Author(s):  
Yifan Xiao ◽  
Long Min ◽  
Xinke Liu ◽  
Wenjun Liu ◽  
Usman Younis ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
High Performance ◽  
Uv Light ◽  
Incident Light ◽  
Chemical Vapor ◽  
Low Noise ◽  
Light Power ◽  
Vapor Growth ◽  
First Order

AbstractThe MoS2 photodetector on different substrates stacked via van der Waals force has been explored extensively because of its great potential in optoelectronics. Here, we integrate multilayer MoS2 on monocrystalline SiC substrate though direct chemical vapor deposition. The MoS2 film on SiC substrate shows high quality and thermal stability, in which the full width at half-maximum and first-order temperature coefficient for the $E_{2g}^1$ Raman mode are 4.6 cm−1 and −0.01382 cm−1/K, respectively. The fabricated photodetector exhibits excellent performance in the UV and visible regions, including an extremely low dark current of ~1 nA at a bias of 20 V and a low noise equivalent of 10−13–10−15 W/Hz1/2. The maximum responsivity of the MoS2/SiC photodetector is 5.7 A/W with the incident light power of 4.35 μW at 365 nm (UV light). Furthermore, the maximum photoconductive gain, noise equivalent power, and normalized detectivity for the fabricated detector under 365 nm illumination are 79.8, 7.08 × 10−15 W/Hz1/2, and 3.07 × 1010 Jonesat, respectively. We thus demonstrate the possibility for integrating high-performance photodetectors array based on MoS2/SiC via direct chemical vapor growth.

Examination of the material properties and performance of thin-diamond film cutting tool inserts produced by arc-jet and hot filament chemical vapor deposition

1996 ◽  
Vol 11 (7) ◽  
pp. 1765-1775 ◽  
Author(s):  
James M. Olson ◽  
Michael J. Dawes
Keyword(s):  
Wear Resistance ◽  
Chemical Vapor Deposition ◽  
Diamond Film ◽  
Vapor Deposition ◽  
Cutting Tool ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
And Performance ◽  
Hot Filament

Thin diamond film coated WC-Co cutting tool inserts were produced using arc-jet and hot-filament chemical vapor deposition. The diamond films were characterized using SEM, XRD, and Raman spectroscopy to examine crystal structure, fracture mode, thickness, crystalline orientation, diamond quality, and residual stress. The performance of the tools was evaluated by comparing the wear resistance of the materials to brazed polycrystalline diamond-tipped cutting tool inserts (PCD) while machining A390 aluminum (18% silicon). Results from the experiments carried out in this study suggest that the wear resistance of the thin diamond films is primarily related to the grain boundary strength, crystal orientation, and the density of microdefects in the diamond film.

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