• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.999-1006
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• 1993

Si3N4(p)-SiC(p) composites were prepared by gas pressure sintering at 190$0^{\circ}C$ for 1 hour. $\alpha$-SiC with average particle size of 0.48${\mu}{\textrm}{m}$ were dispersed from zero to 50vol% in $\alpha$-Si3N4 with average particle size of 0.5${\mu}{\textrm}{m}$. Y2O3-Al2O3 system was used as sintering aids. When 10vol% of SiC was added to Si3N4, optimum mechanical properties were observed; relative density of 98.8%, flextural strength of 930MPa, fracture toughness of 5.9MPa.m1/2 and hardness value of 1429kg/$\textrm{mm}^2$. Grain growth of $\beta$-Si3N4 was inhibited as the amount of added SiC was increased. SiC particles were found inside the $\beta$-Si3N4 intragrains in case of 10, 20 and 30vol%SiC added composites.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.460-467
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• 2003

Al-SiC$_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.12-17
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• 2002

In this paper, an effective ionization coefficient for 4H-SiC is extracted in the form of c .E$^{m}$ from ionization coefficients of electron and hole. Analytical expressions for critical electric field and breakdown voltage of 4H-SiC p$^{+}$n junction are derived by employing the effective ionization coefficient. The analytic results agree well with the experimental ones reported within 10% in error for the doping concentration in the range of 10$^{15}$ cm$^{-3}$ ~10$^{18}$ cm$^{-3}$ . .

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.6
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• pp.398-403
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• 2001

In this paper, effective ionization coefficient for 6H-SiC is determined. Analytical formulas for the parallel plane breakdown voltage of the 6H-SiC p＋n junction are derived by employing the ionization coefficients. The analytical breakdown voltages show good agreement with the numerical results of Dmitriev＇s［3］and the experimental results of Cree Research［9］over the doping range from 10$^{15}$ cm$^{-3}$ to 10$^{18}$ cm$^{-3}$.

• Solar Energy
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• v.6 no.2
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• pp.70-75
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• 1986

The fabrication procedure and characteristics of $Ta_2O_5/Al/SiO_2/p-Si$ MIS solar cells forming a fine grating pattern of aluminum evaporated on to p-type silicon crystal are discribed. The proper temperature for oxide growing of these cells was found to be about $450^{\circ}C$ for 20 minutes with oxygen flow. The conversion efficiency increased about 3% after $750{\AA}$ thickness of tantalium silica film spin on anti-reflective coating. The best results showed that $V_{oc}=0.545V,\;J_{sc}=34mA$ and F.F = 0.65, which represent that the conversion efficiency is 12%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.869-873
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• 2001

The effects of alternate bias stress on p-channel poly-Si TFT\`s has been systematically investigated. We alternately applied positive and negative bias stress on p-channel poly-Si TFT\`s, device Performance(V$\_$th/, g$\_$m/, leakage current, S-slope) are alternately appeared to be increasing and decreasing. It has been shown that device performance degrade under the negative bias stress while improve under the positive bias stress. This effects have been related to the hot carrier injection into the gate oxide rather than the generation of defect states within the poly-Si/SiO$_2$ interface under alternate bias stress.

• Resources Recycling
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• v.20 no.5
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• pp.34-39
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• 2011

Metallurgical grade silicon(MG-Si) was melted with Ca at 1500$^{\circ}C$ under Ar atmosphere. The sample was cooled at 10 $^{\circ}C$/min to room temperature and leached in aqua regia. In the present study, the effect of Ca addition and conditions of acid leaching on removal of Fe and P in MG-Si were investigated. CaSi$_2$ phase was formed at the grain boundary of MG-Si melting with Ca. Also FeSi$_2$ phase was precipitated in CaSi$_2$ phase. By the formation of CaSi$_2$ phase, 97% of Fe and 66 % of P were removed from Ca added MG-Si with the particle size of 600~850${\mu}m$ by aqua regia(more than 30%) leaching.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.28-30
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• 2009

이종접합태양전지에서 p a-Si:H/c-Si의 p a-Si:H의 증착 조건인 $H_2/SiH_4$ 비율, $B_2H_6$의 농도를 변화 시키며 실험하여 이 따라 계면 특성 변화를 연구하였다. pa-Si:H의 $H_2/SiH_4$ 비율이 상승할수록 carrier lifetime이 증가하다 다시 감소하는 경향을 나타내었다. 이는 $H_2/SiH_4$의 비율 중 효과적으로 웨이퍼표면을 효과적으로 passivation하는 지점이 있는 것으로 보인다. $B_2H_6$의 농도는 상승할수록 carrier lifetime이 줄어드는 경향을 보였다. $B_2H_6$에서 농도가 올라감에 웨이퍼 표면의 defect로 작용했을 것으로 생각된다. 이에서 몇몇의 조건으로 태양전지를 제작한 결과 $H_2/SiH_4$ 비율에 따라서는 carrier lifetime은 효율에 그 영향이 미미한 것으로 조사되었고, $B_2H_6$의 농도가 낮을수록 개방전압은 상승하는 결과를 얻어 도핑 농도가 효율에 직접적인 형향을 주는 것으로 나타났다.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.213-219
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• 2002

The CellCaSi, a porous silicate material, was tested for the removal of phosphorus (P as phosphate) in water. The effect of the CellCaSi was investigated on the basis of both particle size (under 1,2, and 4 mm) and added amount (0, 1, 2.5, 5, and 10 g/1) of the CellCaSi. The removal efficiency of phosphorus was highest with a particle size of under 1 mm and also increased with an increasing amount of the CellCaSi. The pH change showed little effect on the phosphorus removal of the CellCaSi. The calcium ion was eluted from the CellCaSi into the water, while the aluminium and iron were not. The eluted calcium ion was combined with dissolved phosphorus and then precipitated. The highest removal efficiency of phosphorus was obtained by the combined addition of the CellCaSi, calcium chloride, and ferric chloride. That is, the phosphorus concentrations of 0.10 and 1.0 mg/1 decreased to 0.03 and 0.47 mg/l by the addition of the CellCaSi (1 g/l), calcium ion (30 mg/l), and ferric ion (1 mg/l) at day 8 after treatment. The water qualities at the end of the experiment were as follows: pH was 8.1 and conductivity was 318 ${\mu}$S/cm (a registered maximum conductivity of 500${\mu}$S/cm for raw and potable wafers).

• Journal of the Korean Applied Science and Technology
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• v.16 no.1
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• pp.33-40
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• 1999

We used Cu as a representative of metals to be directly adsorbed on the bare Si surface and studied its removal DHF, DHF-$H_2O_2$ and BHF solution. It has been found that Cu ion in DHF adheres on every Si wafer surface that we used in our study (n, p, n+, p+) especially on the n+-Si surface. The DHF-$H_2O_2$ solution is found to be effective in removing metals featuring high electronegativity such as Cu from the p-Si and n-Si wafers. Even when the DHF-$H_2O_2$ solution has Cu ions at the concentration of 1ppm, the solution is found effective in cleaning the wafer. In the case the n+-Si and p+-Si wafers, however, their surfaces get contaminated with Cu When Cu ion of 10ppb remains in the DHF-$H_2O_2$ solution. When BHF is used, Cu in BHF is more likely to contaminate the n+-Si wafer. It is also revealed that the surfactant added to BHF improve wettability onto p-Si, n-Si and p+-Si wafer surface. This effect of the surfactant, however, is not observed on the n+-Si wafer and is increased when it is immersed in the DHF-$H_2O_2$ solution for 10min. The rate of the metallic contamination on the n+-Si wafer is found to be much higher than on the other Si wafers. In order to suppress the metallic contamination on every type of Si surface below 1010atoms/cm2, the metallic concentration in ultra pure water and high-purity DHF which is employed at the final stage of the cleaning process must be lowered below the part per trillion level. The DHF-$H_2O_2$ solution, however, degrades surface roughness on the substrate with the n+ and p+ surfaces. In order to remove metallic impurities on these surfaces, there is no choice at present but to use the $NH_4OH-H_2O_2-H_2O$ and $HCl-H_2O_2-H_2O$ cleaning.