• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.285-303
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• 1999

Thin films of hydrogenated amorphous silicon carbide compounds (a-SixC1x:H) of different compositions were deposited on Si substrate by RF plasma-enhanced chemical vapor deposition (PECVD). Experiments were carried out using silane(SiH4) and methane(CH4) as the gas precursors at 1 Torr and at low substrate temperature (25$0^{\circ}C$). The gas flow rate was changed with every other parameters (pressure, temperature, RF power) fixed. The substrate was Si(100) wafer and all of the films obtained were amorphous. The bonding structure of a-SixC1x:H films deposited was investigated by X-ray photoelectron spectroscopy (XPS) for the film compositions. In addition, the surface morphology of films was investigated by atomic force microscopy (AFM).

• 한국의학물리학회지:의학물리
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• 제6권1호
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• pp.65-77
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• 1995

A new gamma camera using a-Si : H photodetectors has been designed for the imaging of heart and other small organs. In this new design the photomultiplier tubes and the position sensing circuitry are replaced by 2-D array of a-Si : H p-i-n pixel photode tectors and readout circuitry which are built on a substrate. Without the photomultiplier tubes this camera is light weight, hence can be made portable. To predict the characteristics and the performance of this new gamma camera we did Monte Carlo simulations. In the simulations 128${\times}$128 imaging array of various pixel sixes were used. $\^$99m/Tc(140keV)and $\^$201/Tl(70keV) were used as radiation sources. From the simulations we could obtain the resolution of the camera and ther overall system, and the blurring effects due to scattering in the phantom. Using the Wiener filter for image processing, restoration of the blurred image could be achieved. Simulation results of a-Si : H based gamma camera were compared with those of a conwentional gamma camera.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 추계학술대회 논문집
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• pp.22-27
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• 1992

Phosphorus doped hydrogenated microcrystalline silicon (${\mu}c$-Si:H) thin films were deposited by PECVD (Plasma Enhanced Chemical Vapour Deposition) method using 10.2% $SiH_4$ gas (diluted in Ar) and 308ppm $PH_3$ gas (diluted in Ar). The structural, optical and electrical properties of the films were investigated as a function of substrate temperature(15 to $400^{\circ}C$) and RF power(10 to 120W). The thin film deposited by varing substrate temperature had columnar structure and microcrystalline phase. The volume fraction of microcrystalline phase in the films deposited at RF power of 80W, increased with increasing substrate temperature up to $200^{\circ}C$, and then decreased with further increasing substrate temperature. Volume fraction of microcrystalline phase increased monotonously with increasing RF power at substrate temperature of $250^{\circ}C$. With increasing volume fraction of microcrystalline, electrical resistivity of films decreased to 0.274 ${\Omega}cm$.

• Transactions on Electrical and Electronic Materials
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• 제9권1호
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• pp.28-32
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• 2008

Hydrogenated microcrystalline silicon(${\mu}c$-Si:H) films were prepared using inductively coupled plasma chemical vapor deposition(ICP-CVD) method, electrical and optical properties of these films were studied as a function of silane concentration. And then, effect of $PH_3\;and\;B_2H_6$ addition on their electrical properties was also investigated for solar cell application. Characterization of these films from X-ray diffraction revealed that the conductive film exists in microcrystalline phase embedded in an amorphous network. At $PH_3/SiH_4$ gas ratio of $0.9{\times}10^{-3}$, dark conductivity has a maximum value of ${\sim}18.5S/cm$ and optical bandgap also a maximum value of ${\sim}2.39eV$. Boron-doped ${\mu}c$-Si:H films, satisfied with p-layer of solar cell, could be obtained at ${\sim}10^{-2}\;of\;B_2H_6/SiH_4$.

• Transactions on Electrical and Electronic Materials
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• 제12권3호
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• pp.89-92
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• 2011

Hydrogenated amorphous carbon (a-C:H) films were deposited by plasma enhanced chemical vapor deposition on silicon substrates. a-C:H thin film was irradiated to a typical He-Cd laser to study its emitting properties. The photoluminescence (PL) intensity during the irradiation achieved a maximum value when 2,000 seconds elapsed. Fourier transform infrared measurement revealed a-C:H thin film suffered transformation from a polymer-like to graphite-like phase during laser irradiation. Thermal annealing was done at various temperatures, ranging from room temperature to $400^{\circ}C$ in the atmosphere, to investigate structural changes in a-C:H film by heat generation during the emission. PL intensity of a-C:H thin film increased 1.5 times without apparent structural change, as annealing temperature increased up to $200^{\circ}C$. However, a-C:H film above $200^{\circ}C$ exhibited significant decrease of PL accompanying dehydrogenation. This led to a red shift of the PL peak.

• 한국표면공학회지
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• 제29권6호
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• pp.797-802
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• 1996

Hydrogenated amorphous silicon carbide (a-SiC:H) films have been deposited on unheated substrates by low frequency (50Hz) plasma using $SiH_4+CH_4+H_2$ gas mixtures. Deposition rate, refractive index, optical band gap, Vickers hardness and IR spectrum of the deposited a -SiC:H films have been measured for various rations of gas flow rates k(=$CH_4/SiH_4$, 0.5k4) with a constant $H_2$ flow rate (100sccm). As k increases, the deposition rate of the a-SiC:H films increases up to the maximum value of about 220nm/h at k=2.5, and then it decreases. The refractive index of the films was 2.6 for k=2.5, while the optical band gap of the films was 3.3eV for k=2.2. The maximum value of Vickers hardness of the films was 1500Hv at k=1. The infrared transmission measurement shows that the films contain both Si-C and Si-$CH_3$ bonds.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.272-275
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• 2005

The high stability of a-Si:H TFTs device is studied with different deposited conditions of $SiN_x$ films by PECVD. The process parameters of $N_2$, $NH_3$ gas flow rate, RF power, and pressure s of hydrogenated amorphous silicon nitride are taken into account and analyzed by Taguchi experimental design method. The $NH_3$ gas flow rate and RF power are two major factors on the average threshold voltage and the a-SiNx:H film's structure. The hydrogen contents in $SiN_x$ films were measured by FTIR using the related Si-H/N-H bonds ratio in $a-SiN_x:H$ films. After the 330,000 sec gate bias stress is applied, the threshold voltages ($V_th$) shift less than 10%. This result indicates that the highly stable a-Si:H TFTs device can be fabricated with optimum gate $SiN_x$ insulator.

• 태양에너지
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• 제5권2호
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• pp.46-53
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• 1985

Hydrogenated amorphous silicon solar cells which are fabricated by photo-chemical vapor deposition (photo-CVD) system has been investigated. In the photo-CVD system which consists of three separate reaction chambers, low-pressure mercury lamp has been used as a light source. The main reactant ($Si_2H_6/He$) gases which are premixed with a small amount of mercury vapor in a mercury-vaporizer kept at $50^{\circ}C$ have been used. Using $C_2H_2$ and $SiH_2(CH_3)_2$ as the carbon source, p-type wide band gap a-SiC:H films have been obtained. The result has been found that the undoped layers of the pin/substrate solar cells are influenced by the residual impurities, such as phosphorus and boron during the deposition process. By minimizing the effect of the impurities in the i-layer and optimizing conditions at the p-layer and p/i interface, the energy conversion efficiency of 9.61 % under AM-1 ($100mW/Cm^2$) has been achieved for pin/substrate solar cells illuminated through their p-layers, using the three separate reaction chamber apparatus. It is expected that a-SiC:H solar cells with the energy conversion efficiency over 10% have been fabricated by Photo-CVD method.

• 한국결정성장학회지
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• 제10권1호
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• pp.1-4
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• 2000

Thin films of hydrogenated amorphous silicon carbide compounds ($a-Si_{x}C_{1-x}:H$) of different compositions were deposited on Si substrate by RF plasma-enhanced chemical vapor deposition (PECVD). Experiments were carried out using silane (SiH$_4$) and methane ($CH_4$) as the gas precursors at 1 Torr and at a low substrate temperature ($250^{\circ}C$). The gas flow rate was changed with the other parameters (pressure, temperature, RF power) fixed. The substrate was Si(100) wafer and all of the films obtained were amorphous. The bonding structure of $a-Si_{x}C_{1-x}:H$films deposited was investigated by X-ray photoelectron spectroscopy (XPS) for the film compositions. In addition, the surface morphology of films was investigated by atomic force microscopy (AFM).

• Transactions on Electrical and Electronic Materials
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• 제1권2호
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• pp.7-11
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• 2000

a-Si:H and poly-Si TFT(thin film transistor) characteristics were investigated using an inverted staggered type TFT. The TFT an as-grown a-Si:H exhibited a low field effect mobility, transconductance, and high gate threshold voltage. The poly-Si films were achieved by using an isothermal and RTA treatment for glow discharge deposited a-Si:H films. The a-Si:H films were cystallized at the various temperature from 600$^{\circ}C$ to 1000$^{\circ}C$. As anneal temperature was elevated, the TFT exhibited increased g$\sub$m/ and reduced V$\sub$ds/. V$\sub$T/. The poly-Si grain boundary passivation with grain boundary trap types and activation energies as a function of anneal temperature. The poly-si TFT showed an improved I$\sub$nm//I$\sub$off/ ratio of 10$\^$6/, reduced gate threshold voltage, and increased field effect mobility by three orders.