• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1002-1004
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• 2009

Solution-processed indium-gallium-zinc-oxide thin-film transistors were fabricated by sol-gel method. By a combinatorial study of InGaZnO multi-component system, optimum molar ratio of In, Ga, and Zn has been selected. By adjusting the In:Ga:Zn molar ratio, TFTs with field-effect mobility of 0.5 ~ 1.5 $cm^2$/V-s, threshold voltage of -5 ~ 5 V, and subthreshold slope of 1.5 ~ 2.5 V/decade were achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.640-643
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• 2007

The effect of plasma damage was investigated on amorphous gallium-indium-zinc oxide (a-GIZO) films and transistors. Ion-bombardment by plasma process affects to turn semiconductor to conductor materials and plasma radiation may degrade to transistor electrical properties. All damages are easily recovered with a $350^{\circ}C$ thermal annealing.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.4-6
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• 2019

본 논문은 Modular Scalable Inverter System에서 큰 부피를 차지하는 인덕터를 저감하기 위한 방법을 제안한다. 최근 전력분야에서는 모듈형 전력변환 시스템을 사용함으로써 다양한 시스템에 필요한 전력을 공급하여 효율을 증가시키고 신뢰성을 높이는 방법들이 대두되고 있다. 하지만 모듈을 병렬로 사용하는 경우에는 모듈 간에 흐르는 순환 전류가 발생하게 된다. 이런 순환전류는 부하로 전력을 공급하지 않기 때문에 시스템 효율을 떨어트리고 전류제어 및 부하 분담을 방해한다. 따라서 병렬형 인버터에는 출력에 순환전류 저감을 위한 인덕터를 사용해야 한다는 단점이 있다. 모듈형 전력변환 장치에서 큰 크기의 출력 인덕터는 시스템 사이즈를 늘리고 비용을 증가시키고 전력밀도가 낮아지게 된다. 따라서 GaN HEMT (Gallium Nitride High Electron Mobility Transistor) 기반 인버터와 순환전류 저감 알고리즘을 사용하여 고속 스위칭을 함으로써 동일한 순환전류 저감 성능을 확보하지만 출력 인덕터의 크기를 줄이는 방안을 제시한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.700-706
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• 2001

In this paper, I have fabricated and measured the gallium nitride(GaN) based Schottky diodes, and have carried out analyses of degradation of Schottky barrier characteristics. To improve of degraded Schottky barrier characteristics, I have carried out several experiments such as N$_2$ plasma exposure, annealing in N$_2$ ambient and annealing after N$_2$ plasma exposure. In the results of these experiments, I have achieved that only annealing in N$_2$ ambient is enough to improve the Schottky barrier characteristics, are temperature of 700$\^{C}$ and time of 90 sec in N$_2$ ambient furnace. for the analysis of these experiments, I have carried out the measurement of electric characteristics and quantitative analysis of etching damage using AES(Aguger Electron Spectroscopy).

• Electrical & Electronic Materials
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• v.12 no.8
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• pp.10-17
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• 1999

본 논문에서는 최근 초고주파영역에서 우수한 고출력 특성을 갖는 것으로 알려진 AlGaN-GaN high-electron mobility transistor(HEMT's)의 최근 기술동향과 함께 응용가능성 및 한계에 대하여 검토하였다. GaN는 약 3.4eV 정도의 큰 밴드갭을 갖는 까닭에 200V 이상의 높은 항복전압을 갖는다. 또한 AlGaN와 이종접합을 형성하는 경우 piezoelectric field에 의하여 1$\times$10\ulcornercm\ulcorner 이상의 높은 밀도의 2DEG(two-dimensional electron gas)의 형성이 가능하고, 상온 전자이동도가 1,200$\textrm{cm}^2$/V-s 이상으로서 초고주파 고출력 전자소자의 구현에 필요한 물성을 갖추고 있다. 현재 cutoff frequency fT가 60GHz이상, maximum frequency fmax가 150GHz 이상의 소자가 개발되었으며, 3W/cm 이상의 cw(continuous wave) 전력밀도가 보고된바 있다. 또한 열전도도가 큰 새로운 기판이 개발되고, heat dissipation을 개선하기 위한 새로운 소자구조가 개발됨에 따라 보다 높은 전력밀도를 갖는 단위소자 또는 MMIC(monolithic microwave integrated circuits)의 구현가능성이 높아지고 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.146-150
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• 2014

As a method of simple patterning of transparent conductive oxide (TCO) films deposited on flexible substrates, laser direct etching was carried out on TCO films sputtered on polycarbonate (PC) substrates. As a result of different binding energies in TCO films, indium tin oxide (ITO) and indium gallium zinc oxide (IGZO) were more easily etched than zinc oxide with different $Nd:YVO_4$ laser beam conditions.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.17-21
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• 2012

This study developed a high-temperature, high-pressure dynamic pressure sensor using LGT(lanthanum gallium tantalate). The sensitivity of the fabricated dynamic pressure sensor was 2.1 mV/kPa and its nonlinearity was 2.5%FS. We confirmed that the high-temperature dynamic pressure sensor operated stably in high-temperature environment at $500^{\circ}C$. The developed dynamic pressure sensor using LGT is expected to be applicable not only to gas turbines but also in various industrial areas in duding airplanes and power stations.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2306-2312
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• 2020

Here we report on the first results of sensitivity evaluation of the gadolinium-aluminum-gallium- garnet (GAGG) scintillation detector with SiPM readout to fast and slow neutrons and, to the natural background and Co-60 γ-radiation as well. Data on sensitivity were obtained using certified dosimetry benches, so it can be utilized in the calculation of detection limits of neutron flux with such type of detectors. It was concluded that use of GAGG scintillator has a good prospect for neutron monitoring in different parts of nuclear research reactors and power plants.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.96-97
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• 2017

본 논문은 Gallium Nitride-Field Effect Transistor(GaN-FET)를 적용한 고방열 및 고전력밀도 모듈형 벅 컨버터를 제안한다. Si-MOSFET를 적용한 벅 컨버터는 높은 스위칭 손실로 인해 고주파수 구동 및 자기소자 사이즈 저감에 한계가 존재하여 고전력밀도화가 어렵다. 반면, 제안된 방식은 스위칭 특성이 우수한 GaN-FET를 적용하여 고주파수 구동이 가능하며, 추가로 평면형 인덕터를 적용함으로써 자기소자의 부피 저감을 통해 컨버터의 고전력밀도화 및 모듈화가 가능하다. 특히, 방열 플레이트 및 케이스로 구성된 새로운 고방열 구조를 통해 방열효과를 극대화 시킬 수 있다. 제안된 모듈형 벅 컨버터의 타당성 검증을 위해 입력전압 48V, 출력전압 24V의 300W급 시작품 제작을 통한 실험결과를 제시한다.

• Journal of Sensor Science and Technology
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• v.24 no.2
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• pp.96-100
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• 2015

In the present study, we developed a real-time radiation-monitoring sensor for an underwater radiation-monitoring system and evaluated its effectiveness using reference radiation sources. The monitoring sensor was designed and miniaturized using a silicon photomultiplier (SiPM) and a cerium-doped-gadolinium-aluminum-gallium-garnet (Ce:GAGG) scintillator, and an underwater wireless monitoring system was implemented by employing a remote Bluetooth communication module. An acrylic water tank and reference radiation sources ($^{137}Cs$, $^{90}Sr$) were used to evaluate the effectiveness of the monitoring sensor. The underwater monitoring sensor's detection response and efficiency for gamma rays and beta particles as well as the linearity of the response according to the gammaray intensity were verified through an evaluation. This evaluation is expected to contribute to the development of base technology for an underwater radiation-monitoring system.