• 전기전자학회논문지
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• 제22권2호
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• pp.344-349
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• 2018

AlGaN/GaN HEMT를 제작하여 상온에서 $-178^{\circ}C$의 저온에 이르기까지 트랜지스터의 전기적인 특성 변화를 연구하였다. 상온에서 264 mA/mm를 나타내던 게이트 길이 $2{\mu}m$인 HEMT의 드레인 전류는 온도의 감소에 따라 변화하여 $-108^{\circ}C$의 온도에서 388 mA/mm로 47%의 증가를 나타냈으며 최대 트랜스컨덕턴스는 121 mS/mm로 부터 183 mS/mm로 증가하였다. 또한 $-178^{\circ}C$의 온도에 이르기까지 -0.39 V의 문턱전압 변화를 보였다. 이러한 변화는 주로 상온에서부터 $-108^{\circ}C$의 온도에서 나타나고 있으며 온도감소에 따른 $720{\Omega}/sq.$ 로부터 $300{\Omega}/sq.$로 감소하는 면저항의 변화와 함께하고 있다.

• 전기학회논문지
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• 제61권11호
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• pp.1646-1649
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• 2012

The $O_2$ annealing technique has considerably suppressed the leakage current of GaN power devices, but this forms NiO at Ni-based Schottky contact with increasing on-resistance. The purpose of the present study was to fabricate 1.5 kV GaN Schottky barrier diodes by improving $O_2$-annealing process and GaN buffer. The proposed $O_2$ annealing performed after alloying ohmic contacts in order to avoid NiO construction. The ohmic contact resistance ($R_C$) was degraded from 0.43 to $3.42{\Omega}-mm$ after $O_2$ annealing at $800^{\circ}C$. We can decrease RC by lowering temperature of $O_2$ annealing. The isolation resistance of test structure which indicated the surface and buffer leakage current was significantly increased from $2.43{\times}10^7$ to $1.32{\times}10^{13}{\Omega}$ due to $O_2$ annealing. The improvement of isolation resistance can be caused by formation of group-III oxides on the surface. The leakage current of GaN Schottky barrier diode was also suppressed from $2.38{\times}10^{-5}$ to $1.68{\times}10^{-7}$ A/mm at -100 V by $O_2$ annealing. The GaN Schottky barrier diodes achieved the high breakdown voltage of 700, 1400, and 1530 V at the anode-cathode distance of 5, 10, and $20{\mu}m$, respectively. The optimized $O_2$ annealing and $4{\mu}m$-thick C-doped GaN buffer obtained the high breakdown voltage at short drift length. The proposed $O_2$ annealing is suitable for next-generation GaN power switches due to the simple process and the low the leakage current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1910-1912
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• 1999

This paper was described electrical characteristics of Metal/GaN contact for application of GaN thin films. The lowest contact resistivity was $1.7\times10^{-7}[\Omega-cm^2]$ at Ti/Al Structure. Mean while, GaN MESFETs have been fabricated with a 250 nm thick channel on a high resistivity GaN layer grown by GAIVBE system. For a gate-source diode reverse bias of 35 V, the gate leakage current was $120{\mu}A$. From the data, we estimate the transconductance for our GaN MESFET to be 25 mS/mm.

• BMB Reports
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• 제36권3호
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• pp.265-268
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• 2003

Retinoic acid (RA) can transform the Golgi apparatus (GA) into a diffuse vacuolar aggregate and increase the toxicity of some immunotoxins that enter into cells by receptor-mediated endocytosis. An ultramorphological study of the RA-induced GA disruption was performed on F2000 fibroblasts. Cultures were treated with 0.11 to $30\;{\mu}M$ RA for 7 - 180 min. The endocytosis of Limax flavus agglutinin-peroxidase conjugate (LFA), and the interactions between a phorbol ester (PMA) and RA concerning GA disruption, were examined. Exposure to $0.33\;{\mu}M$ RA for 20 min transformed the GA into vacuolar aggregate. These vacuoles were not involved in endocytosis since they remained unstained after endocytosis of LFA. However, the lysosomes were involved in endocytosis, as they were strongly stained. Therefore, a RA-induced shift towards lysosomal routing of the entered LFA was presumed. Exposure to PMA made cells resistant to the Golgi-disturbing effects of RA, indicating that protein kinase C plays an important role in this process.

• 전기전자학회논문지
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• 제16권2호
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• pp.116-120
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• 2012

본 논문에서는 밀리미터파 응용에 사용 가능한 우수한 성능의 50 nm InGaAs/InAlAs/GaAs metamorphic HEMT를 구현하였다. 게이트 길이가 50 nm이며 단위 게이트 폭이 30 ${\mu}m$인 2개의 게이트를 가지고 있는 MHEMT의 측정결과, 740 mA/mm의 드레인 포화 전류밀도와 1.02 S/mm의 상호전달 전도도를 얻었으며 전류이득차단주파수와 최대공진주파수는 각각 430 GHz와 406 GHz의 특성을 나타내었다.

• 한국광학회지
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• 제2권2호
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• pp.67-73
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• 1991

단일 종모드로 동작하며, 10mW의 출력을 가지는 AlGaAs 반도체 레이저를 이용하여 Fabry-Perot 공진기형 레이저 증폭기 시스템을 구성하고 비포화 신호이득(unsaturated signal gain), 신호이득 대역폭(signal gain bandwidth), 포화출력(saturation power)을 측정하였다. 증폭기 레이저의 펌핑전류에 따른 비포화 신호 이득은 발진 문턱 전류 근처에서 $0.7\mu\textrmW$의 레이저 출력을 증폭기 레이저에 입사시켰을 때 최대 25dB을 얻었으며 이때 신호이득의 대역폭이 3 GHz 정도임을 확인하였다. 또한 입력 세기(input power)에 따른 비포화 신호이득의 변화를 측정하고 이때의 포화출력을 측정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.44-47
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• 1997

In spite of the addtion of Zn, a high quality of Zn-doped GaN film were prepared. The growth rates of Zn-doped GaN films were varied from 0.14${\mu}{\textrm}{m}$/min to 0.05${\mu}{\textrm}{m}$/min according to the amount of Zn incorporated, The smallest value of the FWHM of x-ray rocking curve was 407 arcsec. The Zn-related Photoluminescence emission peaks which occurred at 2.927 and 2.824 eV shifted toward the low energy region by increasing Zn partial pressures. It was compared between the intensities of D-A pair (3.259eV) and that of the exciton bound to acceptor band(E$_{x-A}$=3.449eV).).

• 한국광학회지
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• 제20권2호
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• pp.71-75
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• 2009

본 논문에서는 전기광학효과를 갖는 $LiNbO_3$ 및 GaAs 물질 기반의 전계 프로브 센서를 제안하고 구현하였다. 이 센서를 이용하여 RF 링 공진필터 소자로부터 방사되는 수평 및 수직방향 성분의 필드세기를 측정하였다. 구현된 $LiNbO_3$ 및 GaAs센서로부터 계산된 감도는 각각 $9.315{\mu}V/\sqrt{Hz}$와 $49.346{\mu}V/\sqrt{Hz}$였으며, 신호 대 잡음비는 ${\sim}50\;dB$와 ${\sim}40\;dB$였다. 그리고 각 센서의 주파수 응답특성은 ${\sim}1.2\;GHz$였다. 마지막으로 센서를 이용하여 테스트 회로의 근접 필드 분포를 측정하였으며, 이는 HFSS 시뮬레이션 결과와 잘 일치하였다.

• 전자공학회논문지A
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• 제32A권2호
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• pp.57-65
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• 1995

The effects of device geometry and layout on high speed performance such as current gain outoff frequency(f$_{T}$) and maximum oscillation frequency(f$_{max}$) are of very improtant for the scaling-down of geterojunction bipolar transistors(HBT$_{s}$). In this paper AlGaAs/GaAs HBTs are fabricated by MBE epitaxial growth and conventional mesa process, and the experimental data of emitter-base geometru dependency of HBT performance are presented in order to provide the quantitative information for optimum device structure design. It is shown that f$_{T}$ and f$_{max}$ are inversely proportional to the emiter stripe width, while the low emitter perimeter/area ratio is better to f$_{T}$ and worse ot f$_{max}$. It is also demonstrated the f$_{T}$ and f$_{max}$ are highly improved by the emitter-base spacing reduction resulting in less parsitic effects. As the result f$_{T}$ of 42GHz and f$_{max}$ of 23GHz are obtained for fabricated HBT with emitter area of 3${\times}20^{\mu}m^{2}$ and E-B spacing of 0.2$\mu$m.m.m.

• 반도체디스플레이기술학회지
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• 제10권4호
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• pp.131-138
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• 2011

We fabricated distributed feedback InGaAsP/InP laser diodes for optical fiber communication module and characterized the lasing properties in continuous wave operation. The active layer of 7-period InGaAsP(1.127 eV)/InGaAsP(0.954 eV) multi-quantum well structure was grown by the metal-organic chemical vapor deposition. The grating for waveguide was also fabricated by the implementation of the Mach-Zehender holographic method of two laser beams interference of He- Cd laser and the fabricated laser diode has the dimension of the laser length of $400{\mu}m$ and the ridge width of $1.2{\mu}m$. The laser diode shows the threshold current of 3.59 mA, the threshold voltage of 1.059 V. For the room-temperature operation with the current of 13.54 mA and the voltage of 1.12 V, the peak wavelength is about 1309.70 nm and optical power is 13.254 mW.