• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.322.1-322.1
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• 2014

Many research groups have studied tandem or multi-junction cells to overcome this low efficiency and degradation. In multi-junction cells, band-gap engineering of each absorb layer is needed to absorb the light at various wavelengths efficiently. Various absorption layers can be formed using multi-junctions, such as hydrogenated amorphous silicon carbide (a-SiC:H), amorphous silicon germanium (a-SiGe:H) and microcrystalline silicon (${\mu}c$-Si:H), etc. Among them, ${\mu}c$-Si:H is the bottom absorber material because it has a low band-gap and does not exhibit light-induced degradation like amorphous silicon. Nevertheless, ${\mu}c$-Si:H requires a much thicker material (>2 mm) to absorb sufficient light due to its smaller light absorption coefficient, highlighting the need for a high growth rate for productivity. ${\mu}c$-SiGe:H has a much higher absorption coefficient than ${\mu}c$-Si:H at the low energy wavelength, meaning that the thickness of the absorption layer can be decreased to less than half that of ${\mu}c$-Si:H. ${\mu}c$-SiGe:H films were prepared using 40 MHz very high frequency PECVD method at 1 Torr. SiH4 and GeH4 were used as a reactive gas and H2 was used as a dilution gas. In this study, the ${\mu}c$-SiGe:H layer for triple solar cells applications was performed to optimize the film properties.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3451-3455
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• 2013

Single-crystalline silicon nanowires (SiNWs) were fabricated by using an electroless metal-assisted etching of bulk silicon wafers with silver nanoparticles obtained by wet electroless deposition. The etching of SiNWs is based on sequential treatment in aqueous solutions of silver nitrate followed by hydrofluoric acid and hydrogen peroxide. SEM observation shows that well-aligned nanowire arrays perpendicular to the surface of the Si substrate were produced. Free-standing SiNWs were then obtained using ultrasono-method in toluene. Alkyl-derivatized SiNWs were prepared to prevent the aggregation of SiNWs and obtained from the reaction of SiNWs and dodecene via hydrosilylation. Optical characterizations of SiNWs were achieved by FT-IR spectroscopy and indicated that the surface of SiNWs is terminated with hydrogen for fresh SiNWs and with dodecyl group for dodecyl-derivatized SiNWs, respectively. The main structures of dodecyl-derivatized SiNWs are wires and rods and their thicknesses of rods and wire are typically 150-250 and 10-20 nm, respectively. The morphology and chemical state of dodecyl-derivatized SiNWs are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy.

• 한국세라믹학회지
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• 제37권1호
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• pp.96-101
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• 2000

Comparative studies on microstructure, and mechanical and anti-oxidation properties between TiN and Ti-Si-N films were performed. The Ti-Si-N films were deposited on high-speed steel and silicon wafer substrates by plasma-assisted chemcial vapor deposition(PACVD) technique. The Si addition to TiN film caused to change the microstructure such as grain size refinement, randomly multi-oriented microstructure, and nano-sized codeposition of silicon nitride in the TiN matrix. The Ti-Si-N film, contains Si content of ∼7 at.%, showed the micro-hardness value of ∼3400 HK, which was higher than the pure TiN film whose hardness was ∼1500HK. The Ti-Si(7 at.%)-N film also showed much improved anti-oxidation properties compared with those of the pure TiN film. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film was formed and retarded further oxidation of the nitridelayer. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film which was characterized by nano-sized precipitates of silicon nitride phase in the TiN matrix and randomly oriented grains.

• 한국세라믹학회지
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• 제47권2호
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• pp.157-162
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• 2010

Effect of starting SiC particle size on nitridation rate and flexural strength of $Si_3N_4$-bonded-SiC (SNBSC) ceramics was investigated by using SiC particles of different size (${\sim}200\;{\mu}m$, ${\sim}100\;{\mu}m$ and ${\sim}45\;{\mu}m$). The specimen prepared from smaller SiC particles resulted in higher nitridation rate after nitridation at $1450^{\circ}C$, owing to the lower packing density in green body. The flexural strength showed maxima after 1-h nitridation for all specimens and then decreased with prolonged nitridation because of local densification-induced pore coarsening. The specimen prepared from smaller SiC particles showed better flexural strength because of smaller pore size and partly higher nitridation rate in the specimen. A maximal flexural strength of 29 MPa was obtained in the specimen with a density of $2.04\;g{\cdot}cm^3$, which was prepared from $45\;{\mu}m$-SiC particles.

• Journal of Power Electronics
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• 제13권4호
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• pp.584-591
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• 2013

In this paper, a hybrid booster power module with Si IGBT and Silicon Carbide (SiC) Schottky Barrier Diode (SBDs) is presented. The switching characteristics of the hybrid booster module are compared with commercial Silicon IGBT/Si PIN diode based modules. We applied the booster power module into a non-isolated on board vehicle charger with a simple buck-booster topology. The performances of the on-vehicle charger are analyzed and measured with different power modules. The test data is measured in the same system, at the same points of operation, using the conventional Si and hybrid Si/SiC power modules. The measured power conversion efficiency of the proposed on-vehicle charger is 96.4 % with the SiC SBD based hybrid booster module. The conversion efficiency gain of 1.4 % is realizable by replacing the Si-based booster module with the Si IGBT/SiC SBD hybrid boost module in the 6.6 kW on-vehicle chargers.

• 한국전기전자재료학회논문지
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• 제18권7호
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• pp.662-666
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• 2005

Silicon nitride $(SiN_x)$ film is a promising material for anti-reflection coating and passivation of multicrystalline silicon (me-Si) solar cells. In this work, a plasma-enhanced chemical vapor deposition (PECVD) system with batch-type reactor tube was used to prepare highly robust $SiN_x$ films for screen-printed mc-Si solar cells. The Gas flow ratio, $R=[SiH_4]/[NH_3]$, in a mixture of silane and ammonia was varied in the range of 0.0910.235 while maintaining the total flow rate of the process gases to 4,200 sccm. The refractive index of the $SiN_x$ film deposited with a gas flow ratio of 0.091 was measured to be 2.03 and increased to 2.37 as the gas flow ratio increased to 0.235. The highest efficiency of the cell was $14.99\%$ when the flow rate of $SiH_4$ was 350 sccm (R=0.091). Generally, we observed that the efficiency of the mc-Si solar cell decreased with increasing R. From the analysis of the reflectance and the quantum efficiency of the cell, the decrease in the efficiency was shown to originate mainly from an increase in the surface reflectance for a high flow rate of $SiH_4$ during the deposition of $SiN_x$ films.

• 전기전자학회논문지
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• 제27권4호
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• pp.630-635
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• 2023

SiC는 고온, 고전압을 비롯한 악조건에서의 내성이 기존 산업분야의 대다수를 점유하고 있는 Silicon에 비해 우수하여 전력반도체 분야에서 Silicon의 위치를 대체하여 가고 있다. 본 논문은 전력 반도체 소자 중 하나인 4H-SiC Planar MOSFET에 알루미늄으로 Gate를 형성하여 다결정 Si 게이트와 대비, 파라미터 값들이 일관성을 갖도록 하였으며, SiC MOSFET의 채널 도핑 농도에 변화를 주어 문턱전압과 항복전압, IV 특성을 연구하였다.

• 전자공학회논문지
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• 제50권6호
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• pp.305-310
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• 2013

본 연구는 Si/$SiO_2$/Si-sub 구조의 SDB(silicon-direct-bonding) 웨이퍼를 이용한 고온용 압력센서의 제작 및 특성을 연구한 것이다. 압력센서는 SDB 웨이퍼의 첫 번째 층의 단결정 실리콘을 이용하여 압저항을 제작하기 때문에 감도가 우수하며, 두 번째 층의 산화막으로 압저항과 실리콘 기판을 절연 분리하여, 일반적인 실리콘소자의 사용 온도 한계인 $120^{\circ}C$ 이상의 고온에서도 사용이 가능하다. 제작된 압력센서는 고감도의 압력감도 및 센서 출력의 직선성 및 히스테리시스 특성이 매우 우수함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 춘계학술대회 논문집
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• pp.42-45
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• 1992

The poly silicon thin films were prepared by solid phase crystallization at 600$^{\circ}C$ of amorphous silicon films deposited on Corning 7059 glass and (100) silicon wafer with thermally grown SiO$_2$substrate by plasma enhanced chemical vapor deposition with varying rf power, deposition temperature, total flow rate. Crystallization time, microstructure, absorption coefficients were investigated by RAMAN, XRD analysis and UV transmittance measurement. Crystallization time of amorphous silicon films was increased with increasing rf power, decreasing deposition temperature and decreasing total flow rate.

• 대한금속재료학회지
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• 제50권12호
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• pp.907-911
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• 2012

High purity silicon can be obtained from Al-Si alloys by a combination of solvent refining and centrifugation. Silicon purification by crystallization of silicon from an Al-Si alloy melt was carried out using 2N and 4N purity aluminum and 2N purity silicon as raw materials. The effect of the purity of raw materials on the final silicon ingot purity by centrifugation was investigated for an Al-50 wt% Si alloy. Alloys were melted using an electrical resistance furnace, and then poured into a centrifuging apparatus. A silicon lump like foam was obtained after centrifugation and was leached by an acid in order to get pure silicon flakes. Then silicon flakes were melted to make a silicon ingot using an induction furnace. The purities of the silicon flakes and silicon ingot were enhanced significantly compared to those of the raw materials of silicon and aluminum. The silicon ingot made of 4N aluminum and 2N silicon showed the lowest impurities.