• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.612-614
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• 2008

Organic photovoltaic effects were studied in a device structure of ITO/CuPc/Al and ITO/CuPc/$C_{60}$/BCP/Al. A thickness of CuPc layer was varied from 10nm to 50nm, we have obtained that the optimum CuPc layer thickness is around 40nm from the analysis of the current density-voltage characteristics in CuPc single layer photovoltaic cell. From the thickness-dependent photovoltaic effects in CuPc/$C_{60}$ heterojunction devices, higher power conversion efficiency was obtained in ITO/20nm CuPc/40nm $C_{60}$/Al, which has a thickness ratio (CuPc:$C_{60}$) of 1:2 rather than 1:1 or 1:3. Light intensity on the device was measured by calibrated Si-photodiode and radiometer/photometer of International Light Inc(IL14004).

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권7호
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• pp.308-314
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• 2005

The 2 GHz film bulk acoustic wave resonator(FBAR), one of the most necessary device of the next generation mobile communication system, consisted of solidly mounted resonator(SMR) structure using Brags reflector, was researched in this paper The FBAR applied SiO$_{2}$ and W had large difference of the acoustic impedance to reflector Al to electrode and ZnO to piezoelectric layer. Specially, the FBAR applied the two-step deposition method to improve the c-axis orientation and increase reproducibility of the fabrication device had good performance. The electrical properties of plasma such as impedance, resistance, reactance, $V_{pp},\;I{pp}$, VSWR and phase difference of voltage and current, was analyzed and measured by RF sensor with the variable experiment process factors such as gas ratio, RF power and base vacuum level about concerning the thickness, c-axis orientation, adhesion and roughness. The FBAR device about the optimum condition resulted reflection loss(S$_{11}$) of -17 dB, resonance frequency of 1.93 GHz, electric-mechanical coefficient(k$_{eff}$) of 2.38 $\%$ and Qualify factor of 580. It was seen better qualify than the common dielectric filter at present and expected on business to the filter device of 2 GHz bandwidth with the MMIC technology.

• 전력전자학회논문지
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• 제22권4호
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• pp.312-323
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• 2017

This paper introduces the bidirectional dc-dc converter design case study, which employs silicon-carbide (SiC) MOSFETs for battery energy storage system (BESS). This converter topology is selected as bidirectional synchronous buck converter, which is composed of a half bridge converter, an inductor, and a capacitor, where the converter has less conduction loss than that of a unidirectional buck and boost converter, and to improve the converter efficiency, both the power stage design and power conversion architecture are described in detail. The conduction and switching losses are compared among three different SiC devices in this paper. In addition, the thermal analysis using Maxwell software of each switching device supports the loss analyses, in which both the 2 kW prototype analyses and experimental results show very good agreement.

• 전기전자학회논문지
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• 제18권2호
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• pp.214-219
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• 2014

본 논문에서는 실리콘 카바이드(silicon carbide)를 기반으로 한 tilt-implanted trench Schottky diode(TITSD)를 제안한다. 4H-SiC 트랜치 쇼트키 다이오드(trench Schottky diode)에 형성되는 트랜치 측면에 경사 이온주입(tilt-implantation)을 하여 소자가 역저지 상태(reverse blocking mode)로 동작 시 trench insulator가 모든 퍼텐셜(potential)을 포함하는 구조를 제안하고, 그 특성을 시뮬레이션을 통해 확인하였다. TITSD는 트랜치의 측면(sidewall)에 nitrogen을 $1{\times}10^{19}cm^{-3}$ 으로 도밍(doping) 하여 항복전압(breakdown voltage) 특성도 경사 이온주입을 하지 않았을 때와 같게 유지하면서 trench oxide insulator가 모든 퍼텐셜을 포함하도록 함으로써 termination area를 감소시켰다. 트랜치 깊이(trench depth)를 $11{\mu}m$로 깊게 하고 최적화된 폭(width)을 선택함으로써 2750V의 항복전압을 얻었고, 동급의 항복전압을 가진 가드링(guard ring) 구조보다 termination area를 38.7% 줄일 수 있다. 이에 대한 전기적 특성은 synopsys사의 TCAD simulation을 사용하여 분석하였으며, 그 결과를 기존의 구조와 비교하였다.

• 한국항행학회논문지
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• 제7권2호
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• pp.211-216
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• 2003

본 논문에서는 오래 전부터 NMOS의 게이트 전극으로 사용된 폴리실리콘을 대체할 수 있는 Ta-Ti 합금의 특성에 대해 연구하였다. 실리콘 기판 위에 열적으로 성장된 $SiO_2$ 위에 Ta과 Ti의 두 타깃을 사용하여 co-sputterring 방법으로 Ta-Ti 합금을 증착하였다. 각각의 타깃은 100W의 sputtering power로 증착하여 시편을 제작하였다. 또한 비교 분석을 위하여 Ta을 100W의 sputtering power로 증착한 시편도 제작하였다. 제작된 Ta-Ti 합금 게이트의 열적/화학적 안정성을 검토하기 위하여 $600^{\circ}C$에서 급속열처리를 수행한 결과 소자의 성능 저하는 나타나지 않았다. 또한 전기적 특성 분석 결과 Ta-Ti 합금은 NMOS에 적합한 일함수인 4.13eV를 산출해 낼 수 있었고, 면저항 역시 폴리실리콘에 비해 낮은 값을 얻을 수 있었다.

• 한국결정성장학회지
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• 제30권3호
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• pp.96-102
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• 2020

본 논문에서는 6H-SiC (0001) 기판 위에 AlN 에피층을 혼합 소스 수소화물 기상 에피택시 방법에 의해 성장하였다. 시간당 5 nm의 성장률로 0.5 ㎛ 두께의 AlN 에피층을 얻었다. FE-SEM과 EDS 결과를 통해 6H-SiC (0001) 기판 위에 성장된 AlN 에피층 표면을 조사하였다. HR-XRD와 계산식을 통해 전위 밀도를 예측하였다. 1.4 × 10⁹ cm^-2의 나사 전위 밀도와 3.8 × 10⁹ cm^-2의 칼날 전위 밀도를 가지는 우수한 결정질의 AlN 에피층을 확인하였다. 혼합소스 HVP E 방법에 의해 성장된 6H-SiC 기판 위의 AlN 에피층은 전력소자 등에 응용이 가능할 것으로 판단된다.

• 한국재료학회지
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• 제8권11호
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• pp.977-981
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• 1998

Si 기판의 온도를 200에서 $500^{\circ}C$까지 변화시켜가면서 고집저 소자의 금속배선으로 응용되고 있는 저저항의 텅스텐 박막을 플라즈마 화학증착 방법에 의해 제작하였다. 이렇게 증착된 텅스텐 박막의 비저항은 $H_2/WF_6 $ 가스의 분압비에 따라 매우 민감하게 작용하는 것을 알 수있다. 플라즈마 밀도가 $0.7W/\textrm{cm}^2$ 이하에서는 박막내에 존재하는 잔류응력이 $2.4\times10^9dyne/\textrm{cm}^2$ 이하이다. 그러나 1.8에서 $2.7W/\textrm{cm}^2$로 증가함에 따라 잔류응력은 $8.1\times10^9$에서 $1.24\times10^{10}dyne/\textrm{cm}^2$로 갑자기 증가하는데 이는 박막을 증착할 때에 플라즈마 밀도가 증가하면 이온이나 radical bombardment 의 영향 때문이다.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.101-106
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• 2022

In this paper, WBG semiconductor such as SiC and GaN were applied as power switches for LCL circuit that can be applied to satellite power systems and the test results of the LCL circuit are reported. P-channel MOSFET and N-channel MOSFET, which were generally used in the conventional LCL circuit, were applied together to expand the utility of the test results. The design and stability evaluation were performed using a Micro Cap circuit simulation program. For the test circuit, a module using each switch was manufactured, and a total of 5 modules were manufactured and the steady state and transient state characteristics were compared. From the experimental results, the LCL circuit for power supply of the satellite power system constructed in this paper satisfied the constant current and constant voltage conditions under various operating conditions. The P-channel MOSFET showed the lowest efficiency characteristics, and the three N-channel switches of Si, SiC and GaN showed relatively high efficiency characteristics of up to 99.05% or more. In conclusion, it was verified that the on-resistor of the switch had a direct effect on the efficiency and loss characteristics.

• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.362-366
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• 2018

Silicon carbide is widely used in power semiconductor devices owing to its high energy gap. In particular, Schottky barrier diode (SBD) and PiN diodes fabricated on 4H-SiC wafers are being applied to various fields such as power devices. The characteristics of SBD and PiN diodes can be extracted from C-V and I-V characteristics. The measured Schottky barrier height (SBH) was 1.23 eV in the temperature range of 298~473 K, and the average ideal factor is 1.17. The results show that the device with the Schottky contact is characterized by the theory of thermal emission. As the temperature increases, the parameters are changed and the Vth is shifted to lower voltages.

• 전력전자학회논문지
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• 제27권3호
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• pp.206-213
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• 2022

This paper presents setting up a laboratory-scale testbed to estimate the aging of power MOSFET devices and integrated power modules by measuring its on-state voltage and current. Based on the aging mechanisms of the component inside the power module (e.g., bond-wire, solder layer, and semiconductor chip), a system to measure the on-state resistance of device-under-test (DUT) is designed and experimented: a full-bridge circuit applies current stress to DUT, and a temperature chamber controls the ambient temperature of DUT during the aging test. The on-state resistance of SiC MOSFET measured by the proposed testbed was increased by 2.5%-3% after 44-hour of the aging test.