Achievement Of Coalesced Oriented Diamond Films On Nickel By Optical Process Control And Methane Enrichment

1997 ◽  
Vol 483 ◽  
Author(s):  
P. C. Yang ◽  
C. A. Wolden ◽  
W. Liu ◽  
R. Schlesser ◽  
R. F. Davis ◽  
...  
Keyword(s):  
Scattered Light ◽  
Chemical Vapor ◽  
Light Signal ◽  
Scanning Electron Micrographs ◽  
Optical Process ◽  
Degree Of Orientation ◽  
Characteristic Features ◽  
Hot Filament ◽  
High Degree ◽  
Optimized Conditions

AbstractReal time in-situ laser reflectometry was used to investigate changes in surface morphology observed during the nucleation of oriented diamond on Ni in a hot filament chemical vapor deposition reactor. Characteristic features observed in the intensities of reflected and scattered light were interpreted by comparison with scanning electron micrographs of the diamond seeded substrates quenched at sequential stages of the process. Based on this analysis, a process was developed in which the scattered light signal was used as a steering parameter. Using this process, oriented nucleation and growth of diamond on Ni can be repeatedly achieved. For the purpose of both countering the loss of carbon atoms and to maximize the density of oriented diamond, different concentrations of methane were added during the high temperature annealing stage to find the optimized conditions. It was found that 0.5% methane in the gas phase produced the best degree of orientation and uniformity. Substrates nucleated at these conditions were grown out into coalesced, 30 μm thick films. Both, (100) and (111) oriented films showed a high degree of orientation. Raman spectra obtained from each orientation showed an intense and narrow diamond signature peak with negligible sp2 carbon or background luminescence.

The deposition of oriented diamond film by hot-filament chemical vapor deposition with separate reactant gas

1999 ◽  
Vol 14 (8) ◽  
pp. 3196-3199 ◽  
Author(s):  
G. C. Chen ◽  
C. Sun ◽  
R. F. Huang ◽  
L. S. Wen ◽  
D. Y. Jiang ◽  
...  
Keyword(s):  
Temperature Field ◽  
Chemical Vapor Deposition ◽  
Temperature Gradient ◽  
Diamond Film ◽  
Vapor Deposition ◽  
Deposition Time ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Degree Of Orientation ◽  
Hot Filament

A (110)-oriented diamond film was deposited by hot filament chemical vapor deposition with H2 and CH4 separately introduced into the reactive zone. The film with a degree of orientation I(220)/I(111) of more than 200% and deposition rate of 2–3 μm/h was obtained for a deposition time of 17 h. The long deposition time enlarged the grain size and enhanced the degree of orientation, but too long a deposition time resulted in random growth. The temperature field was measured and also calculated using a simple model. Both results showed that a temperature field existed with varied gradients along the normal of substrate surface. The (110)-oriented diamond film was deposited in the zone with negative temperature gradient. The change in orientation occurring for long deposition times was ascribed to the change of temperature gradient.

Preparation of Epitaxial BaTiO3 Thin Films by Plasma-Enhanced Metalorganic Chemical Vapor Deposition (Pe-Mocvd)

1991 ◽  
Vol 243 ◽  
Author(s):  
C.S. Chern ◽  
J. Zhao ◽  
P. E. Norris ◽  
Y.Q. Li ◽  
B. Gallois ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Microwave Cavity ◽  
Scanning Electron Micrographs ◽  
High Degree ◽  
Metalorganic Chemical

AbstractThe plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD) process has been successfully used to achieve high quality epitaxial growth of BaTiO3 thin films on (001) LaA103 and (001) NdGaO3 substrates at a substrate temperature of 680°C. The PEMOCVD system, which incorporates a 300-Watt microwave cavity, introduces excited species from an oxygen plasma to lower the required deposition temperature, as compared to thermal MOCVD growth of BaTiO3. X-ray diffraction (XRD) θ-20 scan patterns indicate that there are few randomly oriented grains and impurity phases in the epitaxial BaTiO3 films. Results of XRD ϕ-scans of the BaTiO3 (202) reflection show a modulation pattern of peaks every 90°, which demonstrates that the BaTiO3 thin films have no misorientation along the [100] and [010] directions of the substrates. An XRD ω rocking curve of the BaTiO3 (200) reflection had a narrow FWHM of 0.25°, indicating that the films have a high degree of preferred orientation of <100> perpendicular to the substrates. The high degree of epitaxial crystallinity is further confirmed by Rutherford Backscattering Spectrometry which gives a minimum yield of 7.5% and 11% for the films deposited on LaAIO3 and NdGaO3, respectively. Scanning electron micrographs show that these films have very smooth surface morphologies, which are desirable for device applications.

Characterization of Collagen Fiber Architecture in the Canine Diaphragmatic Central Tendon

1992 ◽  
Vol 114 (2) ◽  
pp. 183-190 ◽  
Author(s):  
M. S. Sacks ◽  
C. J. Chuong
Keyword(s):  
Collagen Fiber ◽  
Volume Fraction ◽  
Random Network ◽  
Scattered Light ◽  
Mechanical Anisotropy ◽  
Primary Group ◽  
Fiber Architecture ◽  
Degree Of Orientation ◽  
Quantitative Results ◽  
High Degree

The diaphragmatic central tendon (DCT), a collagenous soft tissue membrane, acts as a mechanical buffer between the costal and crural muscles. Its direction of mechanical anisotropy has been shown to correspond to the collagen fiber preferred directions [1]. These preferred directions were determined by gross histological examination, and were thus qualitative. In this work we quantified the collagen fiber architecture throughout the DCT using small angle light scattering (SALS). Helium-Neon laser light was passed through tendon specimens and the resultant scattered light distribution, which characterized the local collagen fiber architecture, was recorded with a linear array of five photodiodes. Throughout the DCT two distinct collagen fiber populations were consistently found. For each population three parameters were determined: 1) the preferred directions of collagen fibers, 2) the volume fraction (Vf) of fibers, 3) OI, an orientation index, which ranges from 0 percent for a random network to 100 percent for a perfectly oriented network. Vector maps were used to display results from 1) and 2), and showed a primary group (G1) going from the crural to costal muscles and a secondary one (G2) running perpendicular to G1. Comparisons of Vf between G1 and G2 showed that G1 contained about three times as many fibers as G2, a ratio similar to that found for the degree of mechanical anisotropy [1]. OI were found to be about 60 percent, indicating a high degree of orientation, with no significant regional or population differences (p<0.05). These quantitative results suggest that throughout the DCT the degree of mechanical anisotropy is controlled exclusively by Vf.

Mass Transport Effects In Selectively Deposited Diamond Thin Films

1995 ◽  
Vol 416 ◽  
Author(s):  
Michael C. Kwan ◽  
Karen K. Gleason
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Surface Reaction ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Scanning Electron Micrographs ◽  
First Order ◽  
Reaction Coefficient ◽  
Hot Filament ◽  
Order Surface

ABSTRACTIn order to study the effects of gas phase transport on the growth of hot-filament chemical vapor deposited (HFCVD) diamond, crystallites were selectively grown on a pre-nucleated, oxygen plasma patterned silicon wafer. Growth rate differences across the substrate were observed from scanning electron micrographs. The deposition system was then modeled with a three dimensional finite difference scheme that employed gas phase diffusion of a single growth limiting species from the hot filament to the surface coupled with a first order surface reaction. The variations in the predicted gas phase concentration directly above the surface were adjusted to match the observed growth rate differences through the Dahmk6hler number which was then used to calculate a first order surface reaction coefficient. This value was compared to published reaction coefficients for the abstraction of a surface H-atom by a gas-phase H-atom.

Evaluation of a substrate pretreatment for hot filament CVD of diamond

1994 ◽  
Vol 9 (4) ◽  
pp. 915-920 ◽  
Author(s):  
K. L. Menningen ◽  
M. A. Childs ◽  
H. Toyoda ◽  
L. W. Anderson ◽  
J. E. Lawler
Keyword(s):  
Crystal Size ◽  
Microwave Plasma ◽  
Surface Condition ◽  
Chemical Vapor ◽  
Crystal Nucleation ◽  
Nucleation Density ◽  
Scanning Electron Micrographs ◽  
Input Concentration ◽  
Phase Chemistry ◽  
Hot Filament

The absolute concentration of methyl radicals (CH3) and the mole fraction of acetylene (C2H2) are measured in a hot filament chemical vapor deposition (CVD) system both during and after an initial pretreatment that has been used successfully in microwave plasma and oxyacetylene torch CVD systems to produce more uniform and higher density crystal nucleation. The pretreatment technique, which consists of deposition for a relatively short time with a high input concentration of hydrocarbon in the feed gas, was studied for both methane (CH4) and C2H2 as the input hydrocarbon diluted in H2. Scanning electron micrographs of diamond films deposited under the conditions studied indicate that the pretreatment using CH4 is not effective in increasing the crystal nucleation density, but is moderately effective in increasing the crystal size. The C2H2 pretreatment has no apparent effect upon either the crystal size or nucleation density. The spectroscopie measurements suggest that the surface condition of the filament is the prominent factor affecting the gas phase chemistry both during and after the pretreatment stage.

Microstructure of Carbon Film Deposited Using Hot-Filament Chemical Vapor Deposition

2015 ◽  
Vol 48 (6) ◽  
pp. 104-109
Author(s):  
Youn-Joon Baik ◽  
Do-Hyun Kwon ◽  
Jong-Keuk Park ◽  
Wook-Seong Lee
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Carbon Film ◽  
Chemical Vapor ◽  
Hot Filament

scholarly journals Unusual Dependence of the Diamond Growth Rate on the Methane Concentration in the Hot Filament Chemical Vapor Deposition Process

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 426
Author(s):  
Byeong-Kwan Song ◽  
Hwan-Young Kim ◽  
Kun-Su Kim ◽  
Jeong-Woo Yang ◽  
Nong-Moon Hwang
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Methane Concentration ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Lower Growth ◽  
Filament Temperature ◽  
Diamond Phase ◽  
Hot Filament

Although the growth rate of diamond increased with increasing methane concentration at the filament temperature of 2100 °C during a hot filament chemical vapor deposition (HFCVD), it decreased with increasing methane concentration from 1% CH4 –99% H2 to 3% CH4 –97% H2 at 1900 °C. We investigated this unusual dependence of the growth rate on the methane concentration, which might give insight into the growth mechanism of a diamond. One possibility would be that the high methane concentration increases the non-diamond phase, which is then etched faster by atomic hydrogen, resulting in a decrease in the growth rate with increasing methane concentration. At 3% CH4 –97% H2, the graphite was coated on the hot filament both at 1900 °C and 2100 °C. The graphite coating on the filament decreased the number of electrons emitted from the hot filament. The electron emission at 3% CH4 –97% H2 was 13 times less than that at 1% CH4 –99% H2 at the filament temperature of 1900 °C. The lower number of electrons at 3% CH4 –97% H2 was attributed to the formation of the non-diamond phase, which etched faster than diamond, resulting in a lower growth rate.

A soft X-ray absorption study of nanodiamond films prepared by hot-filament chemical vapor deposition

2003 ◽  
Vol 372 (3-4) ◽  
pp. 320-324 ◽  
Author(s):  
Y.H Tang ◽  
X.T Zhou ◽  
Y.F Hu ◽  
C.S Lee ◽  
S.T Lee ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Absorption Study ◽  
X Ray ◽  
Hot Filament ◽  
X Ray Absorption
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