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  • Title/Summary/Keyword: 이종재료 접합

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DC Characteristic of Silicon-on-Insulator n-MOSFET with SiGe/Si Heterostructure Channel (SiGe/Si 이종접합구조의 채널을 이용한 SOI n-MOSFET의 DC 특성)

  • Choi, A-Ram;Choi, Sang-Sik;Yang, Hyun-Duk;Kim, Sang-Hoon;Lee, Sang-Heung;Shim, Kyu-Hwan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.06a
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    • pp.99-100
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    • 2006
  • Silicon-on-insulator(SOI) MOSFET with SiGe/Si heterostructure channel is an attractive device due to its potent use for relaxing several limits of CMOS scaling, as well as because of high electron and hole mobility and low power dissipation operation and compatibility with Si CMOS standard processing. SOI technology is known as a possible solution for the problems of premature drain breakdown, hot carrier effects, and threshold voltage roll-off issues in sub-deca nano-scale devices. For the forthcoming generations, the combination of SiGe heterostructures and SOI can be the optimum structure, so that we have developed SOI n-MOSFETs with SiGe/Si heterostructure channel grown by reduced pressure chemical vapor deposition. The SOI n-MOSFETs with a SiGe/Si heterostructure are presented and their DC characteristics are discussed in terms of device structure and fabrication technology.

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Rectifying and Nitrogen Monoxide Gas Sensing Properties of a Spin-Coated ZnO/CuO Heterojunction (스핀코팅법으로 제작한 산화아연/산화구리 이종접합의 정류 및 일산화질소 가스 감지 특성)

  • Hwang, Hyeonjeong;Kim, Hyojin
    • Korean Journal of Materials Research
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    • v.26 no.2
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    • pp.84-89
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    • 2016
  • We present the rectifying and nitrogen monoxide (NO) gas sensing properties of an oxide semiconductor heterostructure composed of n-type zinc oxide (ZnO) and p-type copper oxide thin layers. A CuO thin layer was first formed on an indium-tin-oxide-coated glass substrate by sol-gel spin coating method using copper acetate monohydrate and diethanolamine as precursors; then, to form a p-n oxide heterostructure, a ZnO thin layer was spin-coated on the CuO layer using copper zinc dihydrate and diethanolamine. The crystalline structures and microstructures of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy. The observed current-voltage characteristics of the p-n oxide heterostructure showed a non-linear diode-like rectifying behavior at various temperatures ranging from room temperature to 200C. When the spin-coated ZnO/CuO heterojunction was exposed to the acceptor gas NO in dry air, a significant increase in the forward diode current of the p-n junction was observed. It was found that the NO gas response of the ZnO/CuO heterostructure exhibited a maximum value at an operating temperature as low as 100C and increased gradually with increasing of the NO gas concentration up to 30 ppm. The experimental results indicate that the spin-coated ZnO/CuO heterojunction structure has significant potential applications for gas sensors and other oxide electronics.

Fabrication of a-Si:H/c-Si Hetero-Junction Solar Cells by Dual Hot Wire Chemical Vapor Deposition (양면동시증착 열선-CVD를 이용한 a-Si:H/c-Si 이종접합 태양전지 제조)

  • Jeong, Dae-Young;Song, Jun-Yong;Kim, Kyung-Min;Lee, Hi-Deok;Song, Jin-Soo;Lee, Jeong-Chul
    • Korean Journal of Materials Research
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    • v.21 no.12
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    • pp.666-672
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    • 2011
  • The a-Si:H/c-Si hetero-junction (HJ) solar cells have a variety of advantages in efficiency and fabrication processes. It has already demonstrated about 23% in R&D scale and more than 20% in commercial production. In order to further reduce the fabrication cost of HJ solar cells, fabrication processes should be simplified more than conventional methods which accompany separate processes of front and rear sides of the cells. In this study, we propose a simultaneous deposition of intrinsic thin a-Si:H layers on both sides of a wafer by dual hot wire CVD (HWVCD). In this system, wafers are located between tantalum wires, and a-Si:H layers are simultaneously deposited on both sides of the wafer. By using this scheme, we can reduce the process steps and time and improve the efficiency of HJ solar cells by removing surface contamination of the wafers. We achieved about 16% efficiency in HJ solar cells incorporating intrinsic a-Si:H buffers by dual HWCVD and p/n layers by PECVD.

Resistance Spot Welding of Dissimilar Materials of Austenitic Stainless Steels and IF (Interstitial Free) Steels (저항 점 용접을 이용한 AISI 316 스테인레스강과 용융아연도금 강판의 이종접합)

  • Lee, Jin-Bum;Nam, Dae-Geun;Kang, Nam-Hyun;Kim, Yang-Do;Oh, Weon-Tae;Park, Yeong-Do
    • Korean Journal of Materials Research
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    • v.19 no.7
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    • pp.369-375
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    • 2009
  • The spot weldability of dissimilar metal joints between stainless steels (AISI316) and interstitial free (IF) steels were investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensileshear strength, hardness, and microstructure. The fracture surface was investigated by using a Scanning Electron Microscopy (SEM). The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the STS316 sheet was larger due to the higher bulk-resistance. The microstructure of the fusion zone was fully martensite. In order to evaluate the microstructure further, dilution of stainless steels were calculated and imposed onto the Schaeffler diagram. The predicted microstructure from the Schaeffler diagram was martensite. In order to confirm the predicted microstructure, XRD measurements were carried out. The results showed that that initial weld nugget was composed of austenite and martensite.

Effect of Oxygen Mixture Ratio on the Properties of ZnO Thin-Films and n-ZnO/p-Si Heterojunction Diode Prepared by RF Sputtering (산소 혼합 비율에 따른 RF 스퍼터링 ZnO 박막과 n-ZnO/p-Si 이종접합 다이오드의 특성)

  • Gwon, Iksun;Kim, Danbi;Kim, Yewon;Yeon, Eungbum;Kim, Seontai
    • Korean Journal of Materials Research
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    • v.29 no.7
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    • pp.456-462
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    • 2019
  • ZnO thin-films are grown on a p-Si(111) substrate by RF sputtering. The effects of growth temperature and O2 mixture ratio on the ZnO films are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and room-temperature photoluminescence (PL) measurements. All the grown ZnO thin films show a strong preferred orientation along the c-axis, with an intense ultraviolet emission centered at 377 nm. However, when O2 is mixed with the sputtering gas, the half width at half maximum (FWHM) of the XRD peak increases and the deep-level defect-related emission PL band becomes pronounced. In addition, an n-ZnO/p-Si heterojunction diode is fabricated by photolithographic processes and characterized using its current-voltage (I-V) characteristic curve and photoresponsivity. The fabricated n-ZnO/p-Si heterojunction diode exhibits typical rectifying I-V characteristics, with turn-on voltage of about 1.1 V and ideality factor of 1.7. The ratio of current density at ±3V of the reverse and forward bias voltage is about 5.8×103, which demonstrates the switching performance of the fabricated diode. The photoresponse of the diode under illumination of chopped with 40 Hz white light source shows fast response time and recovery time of 0.5 msec and 0.4 msec, respectively.

Photo-Transistors Based on Bulk-Heterojunction Organic Semiconductors for Underwater Visible-Light Communications (가시광 수중 무선통신을 위한 이종접합 유기물 반도체 기반 고감도 포토트랜지스터 연구)

  • Jeong-Min Lee;Sung Yong Seo;Young Soo Lim;Kang-Jun Baeg
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.36 no.2
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    • pp.143-150
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    • 2023
  • Underwater wireless communication is a challenging issue for realizing the smart aqua-farm and various marine activities for exploring the ocean and environmental monitoring. In comparison to acoustic and radio frequency technologies, the visible light communication is the most promising method to transmit data with a higher speed in complex underwater environments. To send data at a speedier rate, high-performance photodetectors are essentially required to receive blue and/or cyan-blue light that are transmitted from the light sources in a light-fidelity (Li-Fi) system. Here, we fabricated high-performance organic phototransistors (OPTs) based on P-type donor polymer (PTO2) and N-type acceptor small molecule (IT-4F) blend semiconductors. Bulk-heterojunction (BHJ) PTO2:IT-4F photo-active layer has a broad absorption spectrum in the range of 450~550 nm wavelength. Solution-processed OPTs showed a high photo-responsivity >1,000 mA/W, a large photo-sensitivity >103, a fast response time, and reproducible light-On/Off switching characteristics even under a weak incident light. BHJ organic semiconductors absorbed photons and generated excitons, and efficiently dissociated to electron and hole carriers at the donor-acceptor interface. Printed and flexible OPTs can be widely used as Li-Fi receivers and image sensors for underwater communication and underwater internet of things (UIoTs).

Ultraviolet LEDs using n-ZnO:Ga/i-ZnO/p-GaN:Mg heterojunction (n-ZnO/i-ZnO/p-GaN:Mg 이종접합을 이용한 UV 발광 다이오드)

  • Han, W.S.;Kim, Y.Y.;Kong, B.H.;Cho, H.K.;Lee, J.H.;Kim, H.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.50-50
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    • 2008
  • ZnO has been extensively studied for optoelectronic applications such as blue and ultraviolet (UV) light emitters and detectors, because it has a wide band gap (3.37 eV) anda large exciton binding energy of ~60 meV over GaN (~26 meV). However, the fabrication of the light emitting devices using ZnO homojunctions is suffered from the lack of reproducibility of the p-type ZnO with high hall concentration and mobility. Thus, the ZnO-based p-n heterojunction light emitting diode (LED) using p-Si and p-GaN would be expected to exhibit stable device performance compared to the homojunction LED. The n-ZnO/p-GaN heterostructure is a good candidate for ZnO-based heterojunction LEDs because of their similar physical properties and the reproducibleavailability of p-type GaN. Especially, the reduced lattice mismatch (~1.8 %) and similar crystal structure result in the advantage of acquiring high performance LED devices with low defect density. However, the electroluminescence (EL) of the device using n-ZnO/p-GaN heterojunctions shows the blue and greenish emissions, which are attributed to the emission from the p-GaN and deep-level defects. In this work, the n-ZnO:Ga/p-GaN:Mg heterojunction light emitting diodes (LEDs) were fabricated at different growth temperatures and carrier concentrations in the n-type region. The effects of the growth temperature and carrier concentration on the electrical and emission properties were investigated. The I-V and the EL results showed that the device performance of the heterostructure LEDs, such as turn-on voltage and true ultraviolet emission, developed through the insertion of a thin intrinsic layer between n-ZnO:Ga and p-GaN:Mg. This observation was attributed to a lowering of the energy barriers for the supply of electrons and holes into intrinsic ZnO, and recombination in the intrinsic ZnO with the absence of deep level emission.

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Characterization for Applying to Optimized Model of Flatform System Step Parts Material for Low-High Platform Railroad Vehicle (저상고상 철도차량용 승강시스템 스텝 부품 소재의 최적화 모델 적용을 위한 특성 평가)

  • Kwak, Hee-Man;Choi, Jung-Muk;Kim, Hyun-Dong;Park, Min-Heung;Kim, Chul-Su
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.1381-1388
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    • 2011
  • Recently, Because of weight lighting and tighten safety regulations of the railway vehicle railroad weight lighting and safety improvement technology is internationally required. Slide step for moving the passenger to high flatform in the railroad vehicle is recognized of important parts. However, Due to high price and weight, it is limited. In this research, In order to apply for railroad, it was redesigned to optimize part count and reduce the price and weight. By choosing honeycombcore as a part for enduring high weight and weight lighting, We produce honeycombpanel of sandwich structure which a different kind connected by using existing stainless(STS304)steel and thermo plasticity glue. Finally, we can find that honeycombpanel is suitable for weight lighting and high weight. As well as, with test result, we can prove that low-high platform railway system will be optimized, if steps are applied to honeycombpanel.

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The Comparisons of Electrical and Optical Properties on Transprant Conducting Oxide for Silicon Heterojunction Solar Cells (실리콘 이종접합 태양전지용 투명 전도 산화막의 전기적, 광학적 특성비교)

  • Choi, Suyoung;Lee, Seunghun;Tark, Sung Ju;Parkm, Sungeun;Kim, Won Mok;Kim, Donghwan
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.57.2-57.2
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    • 2010
  • 투명전도 산화막(Transparent conducing oxide: TCO)은 태양 전지, 터치패널, 가스 센서 등 여러 분야에 적용할 수 있는 물질로서 전기 전도성과 광 투과성을 동시에 가진다. 높은 전기 전도성과 광 투과성을 가지는 Sb:In2O3(ITO)는 투명전도 산화막 재료로써 가장 일반적으로 사용되고 있으나 인듐의 매장량 한계로 인해 가격이 높다는 단점이 있다. 본 연구에서는 ITO 대체 TCO 물질인 Al doped ZnO(AZO)를 rf magnetron sputter를 이용하여 최적의 수소 도핑량을 찾아 ITO의 전기적 광학적 성질과 비교하였다. AZO 박막은(ZnO:Al2O3 2wt.%)타겟을 이용하여 heater 온도 250도에서 슬라이드 글래스 및 코닝 글래스에 증착시켰고 비교군인 ITO박막은 (In2O3:SnO2 10wt.%)타겟을 이용하여 수소 도핑 없이 350도로 증착시켰다. AZO 및 ITO 박막의 전기적 특성은 hall measurement를 이용하여 측정하였고, UV-VIS spectrophotometer로 광학적 특성을 측정하였다. 수소 도핑량이 증가함에 따라 AZO 박막의 캐리어 농도가 증가하여 전기적 특성이 향상되었고, 가시광 영역에서 높은 평균 투과도를 유지 하였다. AZO 박막과 ITO 박막의 전기적 및 광학적 특성을 비교한 결과, 최적 수소 도핑량을 가진 AZO 박막은 ITO 박막에 준하는 특성을 보였다.

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Thin Film Chromel-Alumel Multjunction Thermal Converter (박막형 크로멜-알루멜 다중접합 열전변환기)

  • Jung, In-Sik;Kim, Jin-Sup;Lee, Jung-Hee;Lee, Jong-Hyun;Shin, Jang-Kyoo;Park, Se-Il;Kwon, Sung-Won
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.9
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    • pp.37-45
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    • 1999
  • For the purpose of reducing the output voltage fluctuation of thin film multijunction thermal converter, EVANOHM alloy-S and chromel-alumel thermocouple were used as a thin film heater material and as a thermoelement of thrmopile, respectively. The temperature coefficient of the resistance of thin film EVANOHM alloy-S heater was about 1.4×104/C, which is very small compared to other materials, and thin film chromel-alumel thermocouple showed relatively small difference of the Seebeck coefficients about 38μV/K. The output voltage fluctuation of the thermal converter was about 0.06% for the initial 120 seconds in air and decreased considerably after preheating for 5 minutes or more. The respective AC-DC voltage and current transfer error ranges of the thermal converter were about ±1.6 ppm and ±0.7 ppm in the frequency range from 10Hz to 10 kHz and increased remarkably below 10 Hz or above 10 kHz.

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