• Solar Energy
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• v.6 no.1
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• pp.12-23
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• 1986

The PECVD $SiN_x:H$ films were made from the $SiH_4-N_2$ gas mixtures under such deposition conditions as 0.01 to 1.0 of $SiH_4/N_2$ volume ratio, 0.1 to $0.8W/cm^2$ of RF power, and 100 to $400^{\circ}C$ of substrate temperature. The deposition rate, refractive index, hydrogen concentration, N/Si composition, optical gap and electric conductivity were measured, and the thermal stability and the optimum deposition conditions were investigated for the application of these films to the solar cell materials.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.44-49
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• 2000

Silicon nitride powders, were synthesized by the vapor phase reaction using SiH4-NH3 gaseous mixture. The reaction temperature, ratio of NH3 to SiH4 gas and the overall gas quantity were varied. The synthesized powders were characterized using X-ray, TEM, FT-IR and EA. The synthesized silicon nitride powders were in amorphous state, and the average particle size was about 100nm. TEM analysis revealed that the particle size decreased with increasing reaction temperature and gas flow quantity. As-received amorphous powders were annealed in nitrogen atmosphere at 140$0^{\circ}C$ for 2h, then the powders were completely crystallized at 0.2 ratio of NH3 to SiH4.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.378-381
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• 2008

고효율 a-Si:H/c-Si 이종접합 태양전지를 얻기 위해서는 우수한 c-Si wafer 위에 고품질의 비정질 실리콘박막을 통한 heterointerface를 형성하는 것이 매우 중요하다. 이를 달성하기 위해서는 공정중에 오염되기 쉬운 Si wafer 표면 상태를 정확히 검사하고 잘 관리하여야 한다. 본 연구에서는 세정 및 표면산화에 따른 Si wafer 상태를 Spectroscopic Ellipsometry 및 u-PCD를 이용하여 분석하였으며, <$\varepsilon$2> @4.25eV 값이 Si wafer 상태를 잘 나타내고 있음을 확인하였고 세정 최적화 할 경우 그 값이 43.02에 도달하였다. 또한 RF-PECVD로 증착된a-Si:H 박막을 EMA 모델링을 통해 분석한 결과 낮은 결정성과 높은 밀도를 가지는 a-Si:H를 얻을 수 있었으며, 이를 이종접합 태양전지에 적용한 결과 Flat wafer상에서 10.88%, textured wafer 적용하여 13.23%의 변환효율을 얻었다. 결론적으로 Spectroscopic Ellipsometry가 매우 얇고 고품질의 다층 박막이 필요한 이종접합 태양전지 분석에 있어 매우 유용한 방법임이 확인되었다.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.507-514
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• 1993

The solid state reaction of Mo/Si multilayer thin films produced by RF magnetron sputtering technique was examine dusing differential scanning calorimetry (DSC) and x-ray diffraction, and explained in view of two concepts, effective drivig force and effective heat of formation. In constant scanning rate DSC, there were two exothermic peks which corresponded to the formation of h-MoSi2 and t-MoSi2 , respectively. The activation energyfor theformation of h-MoSi2 was 1.5eV , and that of t-MoSi2 was 7.8eV. Nucleation wa stherate controlling mechanism for each of the silicide formation. Amorphous phase was not formed , which was consistent withtheprediction by the concept of effective driving force. h-MoSi2 the first crystalline phase, was considered to have lower interfacial free energy than t-MoSi2 and by increasing temperature it was transformed into more stable t-MoSi2.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.232-232
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• 2010

Simulation Program (AFORS-HET 2.4.1) was used, include the basic structure of crystalline silicon thin film as above, under the intrinsic a-Si:H films bonded symmetrical structure (Symmetrical structure) were used. The structure of ITO, a-Si p-type, intrinsic a-Si, c-Si, intrinsic a-Si, a-Si n-type, metal (Al) layer has one of the seven. When thickness for each layer was given the change, the changes of a-Si p-type layer and the intrinsic a-Si layer on top had an impact on efficiency. Efficiency ratio of p-type a-Si:H layer thickness was sensitive to, especially a-Si: H layer thickness is increased in a rapid decrease in Jsc and FF, and efficiency was also decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.863-866
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• 2013

SiC crystal ingots were grown on 6H-SiC dual-seed crystals with different surface roughness and different seed orientation by a PVT (Physical Vapor Transport) method. 4H and 15R-SiC were grown on seed crystal with high root-mean-square (rms) value. The polytype of grown crystal on the seed crystal with lower rms value was confirmed to be 6H-SiC. On the other hand, all SiC crystals grown on seed crystals with different seed orientation were proven to be 6H-SiC. The surface roughness of seed crystals had no effect on the crystal structure of the grown crystals. However, the crystal quality of 6H-SiC single crystals grown on the on-axis seed were revealed to be slightly better than that of 6H-SiC crystal grown on the off-axis seed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.197-200
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• 2001

In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and $N_2$ gas ambient annealing method at $950^{\circ}C$ for 10 min. The specific contact resistivity ( $\rho_{c}$ ), sheet resistance($R_s$), contact resistance($R_c$), transfer length($L_T$) were calculated from resistance($R_T$) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were $\rho_{c}=3.8{\times}10^{-5}\Omega cm^{3}$, $R_{c}=4.9{\Omega}$, $R_{T}=9.8{\Omega}$ and $L_{T}=15.5{\mu}m$, resulting average values of another sample were $\rho_{c}=2.29{\times}10^{-4}\Omega cm^{3}$, $R_{c}=12.9{\Omega}$ and $R_{T}=25.8{\Omega}$. The physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.582-588
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• 1997

Synthetic reaction of TAME, ETBE, and MTBE compounds used largely for gasoline octane number enhancer to prevent air pollution was investigated using heteropolyacid catalyst in a fixed bed flow reactor. In the synthetic reaction of TAME, ETBE and MTBE, after hetero atom being replaced with poly atom, the activity of the catalyst, $H_4SiW_{12}O_{40}$ with coordinated bond with W and an hetero atom of Si was the highest among the catalysts tested. Also the activity depended upon the metals replaced which are related to the catalyst acidity. $FeHPW_{12}O_{40}$ and $K_3PM_{o12}O_{40}$ catalysts showed high activity in TAME synthesis, while they were not effective in ETBE and MTBE synthesis. In this study catalysts showing high activity were selected and mixed with equal weight combination of $H_4SiW_{12}O_{40}$ and $Sr_2SiW_{12}O_{40}$ ;$H_4SiW_{12}O_{40}$ and $NaH_2PW_{12}O_{40}$ ; $Fe_{1.5}PW_{12}O_{40}$ and $Mg_2SiW_{12}O_{40}$ ; $Mg_2SiW_{12}O_{40}$ and $Ba_2SiW_{12}O_{40}$. The mixed heteropolyacid catalysts showed higher TBA conversion rate and better selectivity of ETBE and MTBE than the single catalysts.

• Transactions on Electrical and Electronic Materials
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• v.9 no.2
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• pp.73-78
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• 2008

We investigated for comparison of large-area i-a-Si:H and p-a-SiC:H film quality like thickness uniformity, optical bandgap and surface roughness using both ICP-CVD and PECVD on the large-area substrate(diameter of 100 mm). As a whole, films using ICP-CVD could be achieved much uniform thickness and bandgap of that using PECVD. For i-a-Si:H films, its uniformity of thickness and optical bandgap were 2.8 % and 0.38 %, respectively. Also, thickness and optical bandgap of p-a-SiC:H films using ICP-CVD could be obtained at 1.8 % and 0.3 %, respectively. In case of surface roughness, average surface roughness (below 5 nm) of ICP-CVD film could be much better than that (below 30 nm) of PECVD film. HIT solar cell with 2 wt%-AZO/p-a-SiC:H/i-a-Si:H/c-Si/Ag structure was fabricated and characterized with diameter of 152.3 mm in this large-area ICP-CVD system. Conversion efficiency of 9.123 % was achieved with a practical area of $100\;mm\;{\times}\;100\;mm$, which can show the potential to fabrication of the large-area solar cell using ICP-CVD method.