Browsing by Author "HONG, TM"

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BORON-DOPED DIAMOND FILMS USING TRIMETHYLBORATE AS A DOPANT SOURCE IN METHANE CARBON-DIOXIDE GAS-MIXTURES
(1994-04-01)
CHEN, CF
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CHEN, SH
;
HONG, TM
;
WANG, TC
;
材料科學與工程學系
The effects of boron concentration in the gas phase on the morphological features and cathodoluminescence (CL) of polycrystalline diamond films were investigated. The diamond films were prepared on p-type Si(100) substrates by microwave plasma chemical vapour deposition. Trimethylborate vapour was introduced to the CH4-CO2 gas mixture as a dopant source. Secondary ion mass spectroscopy (SIMS), Raman and CL spectroscopy and scanning electron microscopy analysis were performed on the films. The depth profile of SIMS showed that boron was uniformly doped into the diamond film even at a depth of 6 mum. Boron was found to have a significant effect on both the morphology and cathodoluminescence of the deposited films. The surface morphology changed from well-defined facets to ball-like features with increasing gas phase dopant concentration. To obtain doped diamond films of good quality, it is necessary to lower the carbon concentration by decreasing the flow rate of CH4 during the deposition process. The cathodoluminescence of diamond films was investigated in the range 1.8-4.0 eV. The emission peak intensity of CL spectra at 2.3-2.4 eV was found to increase with increasing dopant concentration in the gas phase. The luminescence is explained by donor-acceptor pair recombination, where the acceptor is substitutional boron. This result indicates that the boron atoms can be successfully doped into substitutional sites of the diamond structure.
CHARACTERIZATION AND MORPHOLOGICAL FEATURES OF DIAMOND FILMS AND PARTICLES AFFECTED BY A DIAMOND-LIKE PRECOATED LAYER
(1993-08-03)
CHEN, CF
;
HONG, TM
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
Submicron polycrystalline diamond films and spherical agglomerated diamond particles were deposited from a CH4-H-2 gas system by microwave plasma-enhanced chemical vapour deposition. In the studies on promoting the nucleation density of diamonds reported here, it was found that spherical agglomerated diamond particles and smooth-surface films could be obtained through a two-step process. In the first step, a pre-coated layer and ball-like particles of amorphous carbon with numerous diamond microcrystals were deposited on an Si substrate using a high CH4 concentration (7, 9 and 11 vol.%). Then the CH4 concentration was lowered to 0.6 vol.%, so that a surface layer of collective idiomorphic finer diamond crystals (less than 1 mum) grew on the pre-coated layer and ball-like particles. The surface roughness of the diamond films was 0.02 mum, which was clearly less than that of the diamond film grown directly on the Si substrate. The morphology of agglomerated diamond particles was significantly affected by the concentration of CH4 in the first step. The diamonds were characterized using scanning electron microscopy observations, X-ray diffraction, and Raman and cathodoluminescence spectral analysis.
CHARACTERIZATION OF BORON-DOPED DIAMOND FILMS USING (CH4-CO2) GAS-MIXTURES WITH B(OCH3)3 AS A DOPANT SOURCE BY MPCVD
(1994-08-15)
CHEN, CF
;
CHEN, SH
;
HONG, TM
;
WANG, TC
;
交大名義發表
Boron-doped diamond films were fabricated on p-type and n-type Si(100) substrates by microwave plasma chemical vapour deposition. Tri-methylborate vapour was introduced to the CH4-CO2 gas mixtures as a dopant source. Secondary ion mass spectroscopy (SIMS), Raman and CL spectroscopy, and scanning electron microscopy analysis were performed on the films. The depth profile of SIMS showed that boron was uniformly doped into the diamond film, even at a depth of 6 mum. Boron was found to have a significant effect on both the morphology and the cathodoluminescence of the deposited films. The surface morphology changed from well-defined facets to ball-like features with increasing gas phase dopant concentration. To obtain doped diamond films of good quality, it is necessary to lower the carbon concentration by decreasing the flow rate of CH4 during the deposition process. The cathodoluminescence of diamond films was investigated in the range 1.8-4.0 eV. The emission peak intensity of CL spectra at 2.3 2.4 eV was found to increase with increasing dopant concentration in the gas phase. The luminescence is explained by donor acceptor pair recombination, where the acceptor is substitutional boron. This result indicates that boron atoms can be successfully doped into substitutional sites of the diamond structure.
CHARACTERIZATION OF DIAMOND FILMS DEPOSITED USING C3H6OX-H2 GAS-MIXTURES
(1993-04-13)
CHEN, CF
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CHEN, SH
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HONG, TM
;
WU, SH
;
交大名義發表
Diamond films were synthesized using the vapour of hydrocarbon liquids,, such as C3H6O (propylene oxide), C3H6O2 (1,3-dioxolane) and C3H6O3 (dimethylcarbonate), diluted by a large amount of hydrogen as gas mixtures. The surface morphologies of the diamond films still possessed well-defined facets when the hydrocarbon concentrations were 1.2 vol.%, 0.5 vol.% and 0.3 vol.% for C3H6O3-H-2, C3H6O2-H-2 and C3H6O-H-2 gas mixtures respectively. Diamonds of good quality, according to Raman measurements, were obtained using C3H6O3-H-2, C3H6O2-H-2 and C3H6O-H-2 gas mixtures. Optical emission spectroscopy was used to examine the species in the plasma during the process of diamond growth. Our results show that the characteristics of diamond growth were related to the oxygen content, i.e. O-to-C ratios, of C3H6Ox (x = 1, 2, 3). We found that the diamond formation region could be extended to higher hydrocarbon concentrations for C3H6O3-H-2 mixtures than for C3H6O-H2 and C3H6O2-H2 MixtUreS because of the larger amounts of atomic hydrogen and oxygen-containing species, such as atomic oxygen, oxygen molecules and OH radicals, in the plasma of the C3H6O3-H-2 mixture. Obviously, there was a higher etching rate, resulting in a diamond formation region with a lower growth rate for the C3H6O3-H-2 mixture.
EFFECT OF H2 ADDITION ON DIAMOND GROWTH IN C2H2-CO2 GAS SYSTEM
(1992-06-25)
CHEN, CF
;
HONG, TM
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材料科學與工程學系
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Department of Materials Science and Engineering
GROWTH OF DIAMOND FROM CO2-(C2H2, CH4) GAS SYSTEMS, WITHOUT SUPPLYING ADDITIONAL HYDROGEN GAS
(1992-05-20)
CHEN, CF
;
LIN, CL
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HONG, TM
;
交大名義發表
;
材料科學與工程學系
Recently, we have been searching for a new reaction path in diamond growth and discovered that diamond films can grow without adding extra hydrogen gas to the hydrocarbon feed. Using high pressure microwave chemical vapour deposition and gas systems of CH4-CO2 or C2H2-CO2, icosahedral polycrystalline particles were deposited and the surface of the films revealed a polycrystalline morphology with smooth (111) facets. The growth rate of the film is 3.11-mu-m h-1 in the CH4-CO2 system and 0.98-mu-m h-1 in the C2H2-CO2 system. The carbon ratio range of the former, which grows crystalline diamond, is broader than the latter ratio range. Furthermore, the growth rate of films in the C2H2-CO2 system is twice that of the CH4-H2 System, and similar to the maximum rate in the CO-H2 system. In the CH4-CO2 system, the maximum rate which resulted in crystalline diamond films is about 2-mu-m h-1, which is about four times that of the CH4-H2 system and twice that of the CO-H2 system. We believe that the crystallinity and quality of the film as determined by X-ray diffraction and cathodoluminescence spectral analysis are comparable with those of naturally occurring type IIa diamond.
HOMOGENEOUS AND LARGE-AREA DIAMOND FILM FORMED USING MULTIFILAMENT CHEMICAL-VAPOR-DEPOSITION
(1994-08-15)
CHEN, CF
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HONG, TM
;
WANG, TC
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交大名義發表
;
材料科學與工程學系
IMPROVEMENT OF SELECTIVITY DURING DIAMOND GROWTH UTILIZING A NEW PROCESS
(1995-01-15)
CHEN, CF
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CHEN, SH
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HONG, TM
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TSAI, MH
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交大名義發表
LOW-TEMPERATURE DIAMOND GROWTH AND PLASMA SPECIES ANALYSIS USING METHANE-CARBON DIOXIDE GAS-MIXTURES
(1994-09-15)
CHEN, CF
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CHEN, SH
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HONG, TM
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WANG, DP
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材料科學與工程學系
MICROWAVE DIAMOND SYNTHESIS WITH HIGH OXYGEN HYDROCARBONS (CARBON-DIOXIDE, OXYGEN)
(1993-12-15)
CHEN, CF
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CHEN, SH
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HONG, TM
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KO, HW
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SHEU, SE
Our previous study demonstrated that a higher growth rate and improved crystallinity resulted from using CH4-CO(2)s in diamond deposition. The possibility of diamond synthesis using a high oxygen-containing liquid hydrocarbon, dimethyl carbonate (C3H6O3) supplemented by CO2 or 0(2) was therefore explored in the present study. Well-faceted diamond was deposited when the ratios of the respective flow rates for CO2/C3H6O3 and O-2/C3H6O3 were 6%-8% and 1.5%-2.25%. The growth rates of the diamond films, which were of high quality, were 3.6 and 1.7 mu m h(-1) respectively. The diamond films displayed different surface morphology and crystal features in these gas mixtures, i.e. the diamond film possessed more (311) and (100) facets in the O-2-C3H6O3 mixture at a power of 400 W. The diamond film deposited from 6.75% CO2 in C3H6O3 was indicated by the roughness determination not only to possess a higher growth rate but also to attain a smooth surface with a roughness of 0.048 mu m (R(a)). The surface roughness of the diamond film was 0.083 mu m for 2% O-2 in C3H6O3. The intensities of CO, OH and O produced from O-2-C3H6O3 mixtures were observed by optical emission spectroscopy measurements to be greater than those produced from CO2-C3H6O3 mixtures, but the intensities of C(2)d CH showed the opposite trend. This was the main difference between the CO2-C3H6O3 and O-2-C3H6O3 mixtures. Therefore a larger amount of etching agents appears to block the nucleation of diamond in O-2-C3H6O3 mixtures. The complete results of our study, including Raman and X-ray diffraction analyses, are presented here.
OPTICAL CHARACTERIZATION OF DIAMOND SYNTHESIZED USING CH4-CO2 GAS-MIXTURES WITHOUT SUPPLYING HYDROGEN GAS
(1994-12-15)
CHEN, CF
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CHEN, SH
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HONG, TM
;
LEU, JS
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交大名義發表
Diamond films are the optical choice for IR window applications. Polycrystalline diamond films were synthesized in this study by microwave-plasma-assisted chemical vapour deposition (PACVD) using CH4 + CO2 as reactive gases. The primary purpose of this study is to determine the effect of the deposition conditions on the optical properties of PACVD diamond films. Room temperature optical properties of free-standing diamond films were studied by Fourier transform IR spectroscopy. Experimental results indicate that the refractive index of diamond films is comparable with that of natural diamond. The scattering loss caused by the rough surface of as-grown diamond film was reduced using a two-step process and polishing techniques. The resulting reduction in scattering loss increased the transmission intensity. For low temperature deposited diamond film the intensity of absorption due to carbon-hydrogen stretch bands was higher than that for film deposited at a high temperature. IR spectra are fitted with simulated spectra to determine the background absorption caused by the amorphous carbon contained in the films. Additionally, the background absorption of low temperature deposited diamond film was found to be larger than that of a diamond film deposited at 850 degrees C.
OPTICAL-EMISSION SPECTROSCOPY STUDIES OF THE EFFECTS OF H-2 AND O-2 ADDITION ON DIAMOND SYNTHESIS IN A CO2-CH4 GAS SYSTEM
(1993-08-01)
CHEN, CF
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HONG, TM
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CHEN, SH
;
交大名義發表
;
材料科學與工程學系
OPTICAL-EMISSION SPECTROSCOPY STUDIES OF THE EFFECTS OF NITROGEN ADDITION ON DIAMOND SYNTHESIS IN A CH4-CO2 GAS-MIXTURE
(1995-10-09)
HONG, TM
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CHEN, SH
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CHIOU, YS
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CHEN, CF
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交大名義發表
The influence of nitrogen on the growth of diamond using the gas mixtures of CHS-CO, by microwave plasma chemical vapor deposition was investigated. A clear improvement in the surface morphology and quality of the diamond films indicates the beneficial effect of adding nitrogen to CH4-CO gas mixtures. Analysis using Auger electron spectroscopy and secondary ion mass spectroscopy shows very low and uniform levels of nitrogen in the diamond films. Atomic nitrogen plays a dominant role in C/H/O/N plasma chemical vapor deposition processes because of the amount of oxygen atoms increased via the titration reaction of nitrogen atoms (a high-rate reaction): N+NO-->N-2+O. This produces a significant influence on diamond synthesis in a CH4-CO2-N-2 gas mixture. (C) 1995 American Institute of Physics.
ROLE OF HYDROGEN AND OXYGEN IN DIAMOND SYNTHESIS USING CARBON-DIOXIDE METHANE-GAS MIXTURES
(1993-10-01)
CHEN, CF
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HONG, TM
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CHEN, SH
;
交大名義發表
;
材料科學與工程學系
A negative effect on the quality of diamond film because of the addition of hydrogen to carbon-dioxide-hydrocarbon gases was investigated. To elucidate the role of hydrogen and oxygen in diamond synthesis using microwave plasma chemical-vapor deposition, diamond films were deposited by adding hydrogen and oxygen to carbon-dioxide-methane-gas mixtures. Improvements in the quality of diamond film and extensions of the diamond-forming region were obtained, due to the addition of oxygen to the carbon-dioxide-methane-gas mixtures. The nucleation density of deposits increased when the amount of hydrogen was increased but decreased when the amount of oxygen was increased. The results of optical emission spectroscopy indicate that the amount of atomic hydrogen in the ground state remained nearly the same, respectively, with increasing amounts of hydrogen and oxygen. However, the amount of electronically excited atomic hydrogen and C2 emissions increased with an increase in the amount of added hydrogen; this means that the electronically excited atomic hydrogen did not benefit diamond growth and the C2 radicals facilitated the formation of amorphous or graphitic carbon. In contrast to the addition of hydrogen, when oxygen was added, the electronically excited atomic hydrogen and C2 radicals decreased, and a larger amount of oxygen-containing species such as atomic oxygen and OH radicals was in the plasma, so the quality of the diamond film improved. In summary, adding hydrogen to the carbon-dioxide-methane-gas mixtures had a negative effect on diamond growth, whereas adding oxygen had a beneficial effect.
THE ROLE OF HYDROGEN IN DIAMOND SYNTHESIS FROM CARBON-DIOXIDE HYDROCARBON GASES BY MICROWAVE PLASMA CHEMICAL VAPOR-DEPOSITION
(1992-11-23)
CHEN, CF
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HONG, TM
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交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
We utilized carbon dioxide to replace hydrogen in CO2-(CH4, C2H2, C3H8) gas mixtures and studied the effect on diamond growth of adding a small amount of hydrogen to the system. The deposits were analyzed by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Our results showed that diamond film with high growth rate and good crystallinity could be obtained in these systems without supplying additional hydrogen gas. When the amount of hydrogen was increased, all the deposited film in the systems gradually displayed poorer morphology and crystallinity. This indicates that graphitic or amorphous carbon components in the diamond film increased with the addition of hydrogen, with a resulting negative effect on the quality of the diamond film. The influence of hydrogen on diamond growth is also investigated in this study by comparing growth rates and C:H:O ratios among various CO2-(CH4, C2H2, C3H8) systems.