Browsing by Author "CHEN, CF"

Now showing 1 - 20 of 27

A CHARACTERIZATION MODEL FOR CONSTANT CURRENT STRESSED VOLTAGE-TIME CHARACTERISTICS OF THIN THERMAL OXIDES GROWN ON SILICON SUBSTRATE
(1986-12-01)
CHEN, CF
;
WU, CY
;
交大名義發表
;
工學院
;
National Chiao Tung University
A CHARACTERIZATION MODEL FOR RAMP-VOLTAGE-STRESSED IV CHARACTERISTICS OF THIN THERMAL OXIDES GROWN ON SILICON SUBSTRATE
(1986-10-01)
CHEN, CF
;
WU, CY
;
交大名義發表
;
工學院
;
National Chiao Tung University
BORON-DOPED DIAMOND FILMS USING TRIMETHYLBORATE AS A DOPANT SOURCE IN METHANE CARBON-DIOXIDE GAS-MIXTURES
(1994-04-01)
CHEN, CF
;
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
;
CHEN, SH
;
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
;
材料科學與工程學系
;
Department of Materials Science and Engineering
ELECTRICAL-PROPERTIES OF BORON-DOPED DIAMOND FILMS AFTER ANNEALING TREATMENT
(1995-04-15)
CHEN, CF
;
CHEN, SH
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
Trimethylborate (B(OCH3)(3)) was used to obtain boron-doped (p-type) polycrystalline diamond thin films on a silicon substrate using microwave plasma-assisted chemical vapor deposition. The effect of the doping agent (trimethylborate) was characterized in terms of electrical properties, and the current-voltage (I-V) characteristics of the boron-doped diamond films using aluminum as contacts at room temperature were examined. A surprising result was that annealing improved the electrical properties of boron-doped diamond films. As the boron concentration increased, the forward current decreased because of the effects of impurity scattering, and the I-V characteristics were still rectified. After the samples were annealed in a helium ambient at 900 degrees C for 30 min, the I-V characteristics changed: the higher the concentration of boron in the doped diamond films, the more ohmic was the observed behavior. The differences in the I-V characteristics of annealed and non-annealed films were subsequently confirmed by Fourier transform infrared spectroscopy (FTIR), capacitance-voltage (C-V) measurements, and cathodoluminescence (CL) experiments. The results of these experiments demonstrated that the annealing treatment caused boron atoms initially in inactive sites (e.g. interstitial or clustering sites) to be incorporated into substitutional sites. The increase in substitutional boron atoms altered the I-V characteristics of the boron-doped diamond films.
ENHANCEMENT OF OXIDE BREAK-UP BY IMPLANTATION OF FLUORINE IN POLY-SI EMITTER CONTACTED P-+-N SHALLOW JUNCTION FORMATION
(1994-04-01)
WU, SL
;
LEE, CL
;
LEI, TF
;
CHEN, CF
;
CHEN, LJ
In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p+-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900-degrees-C. As a result, the junction depth of the BF2-implanted device is much larger than that of the boron-implanted device.
GROWTH OF DIAMOND FROM CO2-(C2H2, CH4) GAS SYSTEMS, WITHOUT SUPPLYING ADDITIONAL HYDROGEN GAS
(1992-05-20)
CHEN, CF
;
LIN, CL
;
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
;
HONG, TM
;
WANG, TC
;
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
;
CHEN, SH
;
HONG, TM
;
TSAI, MH
;
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
;
CHEN, SH
;
HONG, TM
;
WANG, DP
;
材料科學與工程學系
LOW-TEMPERATURE GROWTH OF DIAMOND FILMS BY MICROWAVE PLASMA CHEMICAL-VAPOR-DEPOSITION USING CH4+CO2 GAS-MIXTURES
(1994-04-01)
CHEN, CF
;
CHEN, SH
;
KO, HW
;
HSU, SE
;
材料科學與工程學系
Diamond films were deposited on Si substrates at low temperatures using CH4 + CO2 gas mixtures, which are different from conventional mixtures such as CH4 + H-2, CH4 + O2 + H-2 and CO + O2 + H-2. The films were deposited by microwave plasma chemical vapor deposition. High quality diamond films with high growth rates were fabricated at lower temperatures than those used by previous researchers. After 24 h of deposition, the deposited films were characterized using scanning electron microscopy, and their quality was determined by laser Raman spectroscopy and X-ray diffraction. The results showed that, when the microwave power was set at 290 W, well-faceted diamond films were formed in the total gas pressure range 6-25 Torr. The substrate temperatures and the volume ratios [CH4]/[CO2] (in volume per cent) were also changed from 340 to 220-degrees-C and from 60.1 % to 57.3% respectively. The growth rate of diamond films changed from 0.31 to 0.18 mum h-1 in the above growth temperature range. The growth rate of the diamond films increased as the substrate temperature increased. Consequently, we predict that diamond films may be formed using CH4 + CO2 gas mixtures, even at temperatures of less than 200-degrees-C.
MICROWAVE DIAMOND SYNTHESIS WITH HIGH OXYGEN HYDROCARBONS (CARBON-DIOXIDE, OXYGEN)
(1993-12-15)
CHEN, CF
;
CHEN, SH
;
HONG, TM
;
KO, HW
;
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.
MICROWAVE PLASMA CHEMICAL VAPOR-DEPOSITION OF DIAMOND - ITS GROWTH AND CHARACTERIZATION
(1990-12-05)
CHEN, CF
;
NISHIMURA, K
;
KO, ES
;
OGAWA, E
;
HOSOMI, S
Diamond was deposited in both film and particle forms by microwave plasma chemical vapour deposition (CVD) from both CH4-H2 and CO-H2 systems with additive gases of O2 and CO2. The products were comparatively characterized by X-ray diffraction, scanning electron microscopy observation, and Raman and cathodoluminescence spectroscopy. Deposition parameters employed were a power input of 220 W, an H2 flow of 100 cm3 min-1, and a pressure of 3.3 kPa. The addition of O2 or CO2 gas resulted in increasing deposition rates of diamond, up to six times as high as the cases where no additives were used. The addition also resulted in improved crystallinity, so some were comparable with the naturally occurring type IIa diamond. The most favourable results obtained with the system CO-CO2-H2 make the combination appear to be the most promising for diamond synthesis by the microwave plasma CVD process. A possible mechanism of deposition from those gases is suggested.
OPTICAL CHARACTERIZATION OF DIAMOND SYNTHESIZED USING CH4-CO2 GAS-MIXTURES WITHOUT SUPPLYING HYDROGEN GAS
(1994-12-15)
CHEN, CF
;
CHEN, SH
;
HONG, TM
;
LEU, JS
;
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
;
HONG, TM
;
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
;
CHEN, SH
;
CHIOU, YS
;
CHEN, CF
;
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.
PHYSICAL MODEL FOR CHARACTERIZING AND SIMULATING A FLOTOX EEPROM DEVICE
(1992-05-01)
WU, CY
;
CHEN, CF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A physical model has been developed to analyze the dynamic characteristics of a FLOTOX EEPROM device. The effects of the structural parameters such as the area and thickness of the tunneling-oxide and interpoly-oxide layers are characterized by a coupling ratio to describe the discrete programming or erasing operation. The physical parameters including the electron trapping and positive-charge generation effects are used to describe the endurance and retention operations of an EEPROM device. Computer simulations based on this model have been performed to analyze the operations of an EEPROM device, including the effects of three different programming/erasing input voltage waveforms (pulse, exponential rise and triangular). A method for protecting an EEPROM device from overshooting or undershooting during programming or erasing operation is proposed. Therefore, the proposed model can be used as a computer-aided-design (CAD) tool for device design and an efficient simulation tool for describing the dynamic operation and reliability of an EEPROM device.