• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.58-58
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• 2003

최근 전자재료분야 중 고집적 소자를 다루는 분야에서는 산화규소 유전박막의 두께가 얇아짐에 따라 상부전극과 하부기판 사이에서 발생하는 누설전류가 큰 문제가 되었다. 따라서 이를 극복하기 위해 고유전상수를 가진 두꺼운 유전박막을 사용하기 시작하였는데, 그 중 대표적 인 것이 하프늄옥사이드(HfO2)와 알루미나(A12O3)이다. HfO2의 장점은 큰 유전상수를 갖는다는 것이고, A1203의 장점은 열적 안정성 이 뛰어나며, 높은 bandgap에너지를 갖는 것인데, 이 둘의 장점을 살려서 보다 편리한 방법으로 박막을 증착한 것이 바로 HfAlO이다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.3
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• pp.177-181
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• 2018

We prepared ZnS thin films via chemical bath deposition (CBD) in an aqueous solution of ammonia ($NH_3$) and hydrazine ($N_2H_4$). The composition ratio of hydrazine used was 0%, 17%, 22%, 29%, or 50%. We investigated the effects of hydrazine and ammonia on the growth, and the structural and optical properties of ZnS in terms of surface uniformity, voids, and grain size. We found that during the growth of ZnS films, hydrazine was very effective for improving the surface morphology and layer uniformity with fast layer formation, while it had no effect on the bandgap energy, $E_g$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1351-1358
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• 2017

In this work, we investigated radiation hardness of GaN-based transistors which are strong candidates for next-generation power electronics. Field effect transistors with three types of gate structures including metal Schottky gate, recessed gate, and p-AlGaN layer gate were fabricated on AlGaN/GaN heterostructure on Si substrate. The devices were irradiated with energetic protons and alpha-particles. The irradiated transistors exhibited the reduction of on-current and the shift of threshold voltage which were attributed to displacement damage by incident energetic particles at high fluence. However, FET operation was still maintained and leakage characteristics were not degraded, suggesting that GaN-based FETs possess high potential for radiation-hardened electronics.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.83-84
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• 2009

Thin film solar cells based on CIGS continue to be a leading candidate for thin film photovoltaic devices due to their appropriate bandgap, long-term stability, and low-cost production. To date, the most successful technique for the deposition of a CIGS absorber layer has been based on the co-evaporation However, the evaporation process is difficult to scale-up for large-area manufacturing the sputtering and Selenizaton process has been a promising method for low-cost and large-scale production of high quality CIGS In this study, we have used Cu and CuIn alloy targets for precursor deposition the precursor deposited by sputtering Cu and CuIn targets and $CuInSe_2$ thin film is manufactured by Selenization process

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.115.1-115.1
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• 2011

최근 기본적인 pin 구조의 박막 cell 에서 i layer를 최적화 시키는 방안으로 double layer 구조가 많이 연구되고 있다. 본 연구에서는 ASA(Advanced Semicon ductor Analysis) simulation을 이용하여 i-double layer 최적화에 대한 연구를 진행해 보았다. 두께 150/150nm의 i double layer의 band gap 가변을 한 simulation 결과를 보았을 때, p쪽의 band gap이 상승하면서 intrinsic layer 내의 field가 증가하여 recombination center가 감소하였으나 FF의 감소가 있었다. n쪽의 band gap을 상승 시켰을때 n/i 쪽 field 증가로 Voc가 상승되어 초기 효율이 증가하였으나 intrinsic layer내의 field가 감소하여 recombination center가 오히려 증가하였다. 결과적으로 electric field와 효율을 동시에 고려했을 때 두께 300nm, 1.75의 band gap을 가지는 single layer 보다 150/150nm두께에 1.8/1.7 또는 1.8/1.75의 bandgap을 가지는 double layer를 사용하였을 때 보다 높은 효율을 얻을 수 있었다.

• Journal of the Korean Vacuum Society
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• v.5 no.3
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• pp.223-228
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• 1996

$SiO_2$ insulator layers on InSb have been prepared by remote PECVD system a low temperature below $200^{\circ}C$. The effects of deposition pressure, temperature, and gas flow ratio on the physical and electrical characteristics of the $SiO_2$ were studied. The InSb MIS device using $SiO_2$ was fabricated and measured its current-voltage and capacitance-voltage characteritance-voltage charateristics at 77K. The films evaluated Auger electron spectroscopy showed that composition atoms were distributed uniformaly throughout the oxide film and the outdiffusion of substrate atoms into the oxide were few. The leakage current density of the MIS device was about 6.26nA/$\textrm{cm}^2$ at 0.75MV/cm , and the breakdown voltage was about 1MV/cm. The interface-stage density at mid-bandgap extracted from 1MHz C-V measurement was $54\times 10^{11}\textrm{cm}^2-2V^{-1}$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.628-628
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• 2013

Graphene, a single layer of graphite, has raised extensive interest in a wide scientific community for its extraordinary thermal, mechanical, electrical and other properties [1,2]. However, because of zero-band gap of graphene, it is difficult to apply for electronic applications. To overcome this problem, chemical doping is one of way to opening grahene bandgap. According to experimental results, by changing doping concentration and doping time, it is possible to control work function of graphene. We can obtain results through raman spectroscopy, UPS, Sheet resistance. Moreover, electronic properties of doped graphene were studied by making field effect transistors. We were able to control the doping concentration, dirac point of graphene and work function of graphene by formng n-type, p-type doping materials. In this research, the chemicals of diazonium salts, viologen, etc. were used for extrinsic doping.

• Journal of Energy Engineering
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• v.22 no.1
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• pp.58-81
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• 2013

Recently, the technological progress in manufacturing power devices based on wide bandgap materials, for example, silicon carbide(SiC) or gallium nitride(GaN), has resulted in a significant improvement of the operating-voltage range and switching speed and/or specific on resistance compared with silicon power devices. This paper will give an overview of the status on The Next generation Power Devices such as SiC/GaN with a focus on commercialization and research.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.840-843
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• 2001

In this study, temperature dependency of current gain for AlGaAs/GaAs/GaAs HBT is analytically proposed over the temperature range between 300K and 600K. Energy bandgap, effective mass, intrinsic carrier concentration are considered as temperature dependent parameters. Collector current which is numerically calculated is then analytically expressed to enhance the speed of calculation for current gain. From the results, current gain decreases as the temperature increases. These results will be used to expect the unity current gain frequency f$_{T}$ in conjunction with emitter-base and collector- base capacitances.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.40-43
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• 1995

In this paper, structual, optical and electrical properties of CdZnS thin films prepared by electron beam evaporation method were studied. The crysta1 structure of CdZnS films deposited was hexagonal type with preferential orientation of the (002) plane parallel to the substrate. The results of optical transmittance of the CdZnS film show that absorption edge is shifted to ZnS and optical bandgap was larger wish increasing ZnS content. The resistivity of the CdZnS film is decreasing with increasing ZnS content and mininum for 20 mole%.