• 한국전기전자재료학회논문지
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• 제22권1호
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• pp.74-80
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• 2009

In the structure of ITO/N,N'-diphenyl-N,N' bis (3-methylphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris (8-hydroxyquinoline)aluminum($Alq_3$)/Al device, we studied the efficiency improvement of organic light-emitting diodes due to variation of deposition rate of hole transport layer (TPD) materials using hole-size of crucible boat. The thickness of TPD and $Alq_3$ was manufactured 40 nm, 60 nm, respectively under a base pressure of $5{\times}10^{-6}$ Torr using a thermal evaporation. The $Alq_3$ used for an electron-transport and emissive layer were evaporated to be at a deposition rate of $2.5\;{\AA}/s$. When the deposition rate of TPD increased from 1.5 to $3.0\;{\AA}/s$, we studied the efficiency improvement of TPD using the hole-size of crucible is 1.0 mm. When the deposition rate of TPD is $2.5\;{\AA}/s$, we found that the average roughness is rather smoother, the luminous efficiency the external quantum efficiency is superior to the others. Compared to the two from the devices made with the deposition rate of TPD is $2.0\;{\AA}/s$ and $3.0\;{\AA}/s$, the external quantum efficiency was improved by four-times and two-times, respectively.

• 대한기계학회논문집B
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• 제20권3호
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• pp.988-1004
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• 1996

The characteristics of flow and oxygen concentration are numerically studied in Czochralski 8" silicon crystal growing process considering radiative heat transfer. The analysis of net radiative heat flux on all relevant surfaces shows growing crystal affects the heater power. Furthermore, the variation of the radiative heat flux along the crystal surface in the growing direction is confirmed and should be a cause of thermal stress and defect of the crystal. The calculated distributions of temperature and, heat flux along the wall boundaries including melt/crystal interface, free surface and crucible wall indicate that the frequently used assumption of the thermal boundary conditions of insulated crucible bottom and constant temperature at crucible side wall is not suitable to meet the real physical boundary conditions. It is necessary, therefore, to calculate radiative heat transfer simultaneously with the melt flow in order to simulate the real CZ crystal growth. If only natural convection is considered, the oxygen concentration on the melt/crystal interface decreases and becomes uniform by the application of a cusp magnetic filed. The heater power needed also increases with increasing the magnetic field. For the case of counter rotation of the crystal and crucible, the magnetic field suppresses azimutal flow produced by the crucible rotation, which results in the higher oxygen concentration near the interface.

• 한국결정성장학회지
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• 제31권2호
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• pp.63-68
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• 2021

본 연구에서는 NbC 코팅된 도가니가 SiC 단결정 품질에 미치는 영향을 조사하였다. 실험은 흑연 도가니와 NbC 코팅된 도가니를 사용하였으며, 두 실험의 결과를 체계적으로 비교 분석하였다. SiC 결정 성장은 Ar 분위기에서 2300℃ 이상의 온도와 5 Torr의 압력조건에서 PVT 법을 사용하여 진행하였다. 성장된 SiC 결정은 양면 그라인딩과 연마 가공 후 Raman 분석을 통해 결정상 분석, HR-XRD 분석으로 결정성을 분석하였다. 또한 KOH 에칭 후 광학현미경 분석과 SIMS 분석으로 결함 밀도 및 불순물 농도를 분석하여 두 웨이퍼의 품질을 비교하였다.

• 한국결정성장학회지
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• 제32권3호
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• pp.115-120
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• 2022

반도체 웨이퍼용 실리콘 잉곳 제조과정에서 사용되는 석영유리 도가니 내측표면의brownish ring (BR)에 대해 연구하였다. BR의 크기는 20~30 ㎛이고 비대칭 갈색 고리형태이다. 도가니 위치에 따라 BR의 크기와 분포가 상이하며, Si 잉곳 성장시 도가니 온도가 가장 높은 round 부가 가장 크고 많았다. BR은 석영유리보다 열팽창계수가 큰 cristobalite를 함유하고 있어 표면 crack이 나타나는 것으로 판단된다. BR의 발색 현상과 p in hole은 산소 결손에 의한 것으로 생각된다.

• 한국세라믹학회지
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• 제17권4호
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• pp.203-207
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• 1980

The optical absorption of high index glasses of the system TiO2-BaO-B2O3 prepared from the raw materials for an optical waveguide glass has been measured in the near ultraviolet region. The amount of Ti3+ in the glass could be reduced to a level less than 5 ppm by melting a batch added with pure nitric acid, using a fused quartz crucible in an oxygen gas atmosphere. The ultra-pure glass of 10mm thick prepared in such a way did not show any appreciable color even for the one containing 30 mol% TiO2 and having refractive index nD of 1.84 and Abbe's number vD of 28.8. The wavelength of ultraviolet absorptin edge was longer for the glass of higher index and higher dispersdion. The melting of a TiO2 containing glass in a platinum crucible resulted in a coloration of the glass due to the dissolved plutinum from the crucible, which was more intense for the one containing larger amount of TiO2.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.739-744
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• 1996

The U solubility in the Zircaloy melt including the other investigators' result was investigated in a range of reaction temperatures from 2223k to 2473k and for the mole ratios of UO$_2$ crucible/Zircaloy-4 melt(subsequently abbreviated as UO$_2$/Zry) from 2.4 to 18.2, The U solubility in the melt increased with increasing reaction temperature and with decreasing the mole ratio of UO$_2$/Zry. An empirical correlation was obtained as functions of UO$_2$/Zry mole ratio and reaction temperature including other investigators' results. The experimental results with use of internally heated fuel element simulators were analyzed by the empirical correlation from UO$_2$ crucible experiments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.223-223
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• 2010

태양 전지에 사용되는 실리콘의 전자기 유도 용융 기술은 잉곳(ingot)의 성장 및 금속 정련 등의 핵심 공정인 실리콘 용융에서 사용되는 중요한 기술이다. 하지만, 유도 용융에 사용되는 흑연 도가니에 의한 실리콘의 오염은 실리콘의 순도저하에 요인으로 작용한다. 흑연 도가니와 용융된 실리콘이 접하는 계면에서 탄소의 오염이 발생하게 되며, 실리콘 내부에 흡수한 탄소는 대표적인 비금속 불순물로 태양전지 효율을 감소시킨다. 본 연구에서 사용되는 흑연 도가니는 유도 코일의 전자기력에 의해 실리콘과 무접촉 또는 연접촉이 가능한 구조이다. 또한, 유도 자기장을 이용하여 실리콘과 같은 반도체를 용융할 경우, 고상에서의 낮은 전기전도도로 인해 효과적인 줄-발열(Joule Heating)이 불가능하므로 플라즈마와 같은 보조 열원을 필요로 한다. 본 연구에서는, 보조 열원 없이 세그먼트(segment)된 흑연 도가니를 이용한 실리콘 용융 연구를 진행하였다.

• 대한기계학회논문집
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• 제19권5호
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• pp.1308-1318
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• 1995

The influence of varying rotation speed of both crystal and crucible was numerically investigated for the Czochralski silicon-crystal growth. Based on a simplified model assuming flatness of free surfrae, the Navier-Stokes Boussinesq equations were employed to identify the flow pattern, temperature distribution as well as the shape of the melt/crystal interface. The present results showed that the interface shape was relatively convex with respect to the melt at lower pulling rate and tended to be concave as the pulling rate increased. In particular, the experimentally observed gull-winged shape of the interface was qualitatively in agreement with the predicted shape. The rotation of crystal alone little affected the growth system. When the rotation speed of the crucible was increased, there occurred inversion of the interface shape from convex to concave pattern. At rapid rotation of the crucible, an interesting channel formation was predictied primarily due to the assumption of laminar flow.

• 한국결정성장학회지
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• 제15권4호
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• pp.129-134
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• 2005

초크랄스키 단결정장치내 실리콘 유동의 자기장효과에 대한 수치해석을 하였다. 8" 단결정 성장과정에서 난류 모형을 사용하여 수송현상을 계산하였다. 도가니 회전수가 작으면 자연대류가 지배적이었다. 도가니 회전수가 증가할수록 강제대류가 증가되며 온도 분포는 더 넓어진다. cusp 자기장을 인가하면 도가니근처의 유동이 크게 감소하며 온도분포는 전도의 경우와 비슷해진다.

• 한국세라믹학회지
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• 제30권4호
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• pp.309-315
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• 1993

Gas pressure sintering is a promising process in various densification methods of high strength Si3N4 ceramics. Environmental influences on gas pressure sintering of Si3N4 was investigated with the variationof packing powder, specimen container and N2 gas pressure. The specimens had higher density, larger weight loss and inhomogeneous color in graphite specimen container than in SN26 crucible. The variations of sintering densities in various packing powders (Si3N4, SN26, AlN, BN) were very small but SiC powder was synthesised in graphite crucible with Si3N4 packing powder, aluminium oxynitride compounds were synthesised in SN26 crucible with AlN packing power. Also N2 gas pressure over 20kg/$\textrm{cm}^2$ reduced the densification of Si3N4 in one step-gas pressure sintering. As the result of two step-gas pressure sintering at 700kg/$\textrm{cm}^2$ for 15min., relative density of 99.9% and 3-point bending strength of 1090MPa and dense microstructure of 3~4${\mu}{\textrm}{m}$ grain size were obtained.