• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.939-942
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• 2016

One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (N_d) of the active layer on the J-V curve. When the active layer thickness was varied (for N_d = 8×10¹⁷ cm^-3) from 800 nm to 100 nm, the reverse saturation current density (J_o) changed from 3.56×10^-5 A/cm² to 9.62×10^-11 A/cm² and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (N_d = 4×10¹⁵ cm^-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (J_o = 9.62×10^-11 A/cm²) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.10
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• pp.1019-1023
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• 2012

In this research, a novel direct-aluminum-heating-induced crystallization method was developed for the purpose of application to solar cells. By applying a constant current of 3 A to an aluminum thin film, a 200-nm-thick amorphous silicon (a-Si) thin film with a size of $1cm{\times}1cm$ can be crystallized into a polycrystalline silicon (poly-Si) thin film within a few tens of seconds. The Raman spectrum analysis shows a peak of 520 $cm^{-1}$, which verifies the presence of poly-Si. After removing the aluminum layer, the poly-Si thin film was found to be porous. SIMS analysis showed that the porous poly-Si thin film was heavily p-doped with a doping concentration of $10^{21}cm^{-3}$. Thermal imaging shows that the crystallization from a-Si to poly-Si occurred at a temperature of around 820 K.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.303-308
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• 2018

Silicon/Carbon (Si/C) composite as anode materials for lithium-ion batteries was synthesized to find the effect of binders and an electrolyte additive. Si/C composites were prepared by two step method, including magnesiothermic reduction of SBA-15 (Santa Barbara Amorphous material No. 15) and carbonization of phenol resin. The electrochemical performances of Si/C composites were investigated by charge/discharge, cyclic voltammetry and impedance tests. The anode electrode of Si/C composite with PAA binder appeared better capacity (1,899 mAh/g) and the capacity retention ratio (92%) than that of other composition coin cells during 40 cycles. Then, Vinylene carbonate (VC) was tested as an electrolyte additive. The influence of this additive on the behavior of Si/C anodes was very positive (3,049 mAh/g), since the VC additive is formed passivation films on Si/C surfaces and suppresses irreversible changes.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.359-361
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• 1998

Visible photoluminescence(PU was observed from hydrogenated amorphous silicon deposited on silicon(a-Si : H/Si) using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR- PECVD) with silane ($SiH_{4}$) gas as the reactant source. The PL spectra from a-Si : H/Si were very similar to those from porous silicon. Hydrogen contents of samples annealed under oxygen atmosphere for 2minutes at $500^{\circ}C$ by rapid thermal annealing were reduced to 1~2%, and the samples did not show visible PL, indicating that hydrogen has a very important role in the PL process of a- Si : H/Si. As the thickness of deposited a-Si : H film increased, PL intensity decreased. The visi¬ble PL from a-Si: H deposited on Si by ECR-PECVD with $SiH_{4}$ . is suggested to be from silicon hydrides formed at the interface between the Si substrate and the deposited a-Si : H film during the deposition.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.40-44
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• 2010

Laser assisted machining (LAM) has been researched in order to machine the silicon nitride ceramics economically and effectively. LAM is an effective machining method by local heating of the cutting part to the softening temperature of the silicon nitride using laser beam. When silicon nitride ceramics is heated using a laser beam, the surface of silicon nitride ceramic is softened, oxidized and decomposed. And then surface hardness is decreased. Through machining in low viscosity and hardness conditions, silicon nitride was machined effectively and the life span of tool was increased. The plastic deformation was occurred due to softening of amorphous YSiAlON above $ 1,000^{\circ}C$. Transgranular fracture of ${\beta}-Si_3N_4$ was occurred when YSiAlON was not softened, but mostly intergranular fracture was occurred by the plastic deformation of softened YSiAlON.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.64-68
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• 1995

Silicon films were deposited at $430^{\circ}C$ by remote plasma chemical vapor deposition(RPECVD) with a gas mixture of $Si_2H_6/SiF_4/H_2$. The silicon films deposited without and with $SiF_4$ were characterized using atomic force microscopy(AFM), transmission electron microscopy(TEM) and X-ray diffraction(XRD). Both silicon films have the same rugged surface morphology, but, the silicon film deposited with $SiF_4$ exhibits more rugged. The silicon film deposited without $SiF_4$ is amorphous, whereas the silicon film deposited with $SiF_4$ is polycrystalline with very small needle-like grains which are perpendicular to the substrate and uniformly distributed in the thickness of the film. The silicon film deposited with $SiF_4$ was found to have a preferred orientation along the growth direction with the<110> of the film parallel to the <111> of the substrate. The effect of $SiF_4$ during RPECVD was discussed.

• Korean Journal of Materials Research
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• v.5 no.2
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• pp.203-207
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• 1995

Polysilicon this film transistors (poly-Si TFTs) with different channel dimensions were fabricated on low-temperature crystalized amorphous silicon films and on as-deposited polysilicon films. The electrical characteristics of these TFTs were characterized and compared. The performance of the TFTs fabricated on the solid-phase crystalized amophous silicon films ws showon to be superior to that of the TFTs fabricated on the as-deposited polysilicon films. It was found that the performance of poly-Si TFTs depends strongly on the material characteristics of the polysilicon films used as the active layers, but only weakly on the channel dimensions.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.67-68
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• 2000

Polycrystalline silicon (poly-Si) thin film transistors (TFT's) employing vertical amorphous silicon (a-Si) offsets have been fabricated without additional photolithography processes. The a-Si offset has been formed utilizing the poly-Si grain growth blocking effect by thin native oxide film during the excimer laser recrystallization of a-Si. The ON current degradation of the new device after 4 hour's electrical stress was reduced by 5 times compared with conventional poly-Si TFT's.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.541-546
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• 1990

The current conduction and dielectric breakdown properties of oxide grown on phosphorous-doped polysilicon have been investigated by means of the ramped I-V measurements. The effective barrier heights of polyoxide grown by different silicon deposition and oxidation conditions were calculated from the Fowler-Nordheim tunneling characteristic. The average critical fields were also obtained for each film. From the results, the high temperature oxided polyoxide grown on amorphous silicon film shows superior electrical characteristics comparing to the other films.

• Solar Energy
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• v.8 no.2
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• pp.73-76
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• 1988

Thick films based on the mature crystalline silicon technology are expected to exhibit eversmaller cost reduction. The thin-film-based technology is, however, expected to exhibit a much sharper drop in cost as it develops. In this report, technology and recent R & D of thin film solar cell, such as amorphous silicon, cadnium telluride, copper indium diselenide and gallium arsenide, are described. Perspectives of world photovoltaic market and solar cell price are also described.