• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.42-49
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• 1993

In this paper, switched-capacitor building block presented which are suitable for implementation in GaAs MESFET technology. They include a current source, a gain stage, and an operational amplifier. Switched-capacitor design techniques are discussed that minimize filter sentsitivity to finite gain of the GaAs operational amplifier. Simulation results are presented on third-order elliptic lowpass ladder filter at a sampling rate of 5GHz.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.9
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• pp.24-29
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• 1993

The 607 nm GaInP/AlInP distributed bragg reflector (DBR) lasers using the second order gratings period of 184.7 nm were fabricated by gas source molecular beam epitaxy (GSMBE) and the conventional holographic method. GaInP/AlInP DBR lasers show single mode operations up to 1.8 times the threshold currents with a wavelength of 607 nm at 140 K and a wavelength shift of 0.033 nm/K is observed. No mode hopping was found in the temperature ranging from 120 to 165K.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.109-109
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• 2003

III- V ferromagnetic semiconductor has attracted great attention as a potential application for spintronics due to a successful demonstration of spin injection from ferromagnetic GaNnAs into semiconductor. GaMnN may be one of the possible candidates for room temperature operation. Samples were grown on sapphire (0001) substrate at $650^{\circ}C$ via molecular beam epitaxy with a single Precursor of (Et$_2$Ga(N$_3$)NH$_2$$CH_3$) and solid source of Mn at different Mn source temperature. The background pressure is low 10$^{-10}$ Torr and the samples growth pressure was 1.4 $\times$ 10$^{-6}$ Torr.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.510-514
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• 2005

We have investigated the excitation-light source dependence of photo-catalytic efficiency for the benzene removal. The photo-catalytic module for the benzene removal is fabricated by a combination of GaN-based ultraviolet light-emitting diode (UV GaN-LED) and $TiO_2$ thin film coated on an aluminum plate. The benzene reduction rates of 365 nm and 375 nm modules at 60 mA junction current are approximately $8.95\;\%/Hr$ and $9.2\;\%/Hr$, respectively, which indicates that 365 nm GaN-LED is more effective than 375 nm GaN-LED. The benzene reduction efficiency is also noticeably dependent on the excitation wavelength and excitation-light power, as well as it is increased with the shorter wavelength and higher excitation power. This result exhibits that UV GaN-LED is useful to remove the volatile organic compounds (VOCs) existing in the environment.

• Proceedings of the KIEE Conference
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• 1999.07d
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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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.89-90
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• 2009

Three kind of surface-leakage-test-patterns were fabricated and measured in order to investigate the surface leakage current of AlGaN/GaN heterostructures through etched GaN buffer surface and mesa wall. The pattern which contain the mesa wall has the largest surface leakage current among them. The leakage current due to the mesa wall is predominant source of the leakage current of AlGaN/GaN devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.46-47
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• 2005

이번 연구는 $BCl_3/CF_4$ 플라즈마를 사용하여 반도체소자 제조 시 널리 이용되는 GaAs 계열반도체 중 대표적인 재료인 GaAs/AlGaAs 및 GaAs/InGaP 구조를 선택적으로 건식 식각한 후 분석한 것이다. 공정변수로는 ICP 소스파워를 0-500W, RIE 파워를 0-50W 그리고 $BCl_3/CF_4$ 가스 혼합비를 중점적으로 변화시켰다. $BCl_3$ 플라즈마만을 사용한 경우 (20$BCl_3$, 20W RIE power, 300W ICP source power, 7.5mTorr) 는 GaAs:AlGaAs의 선택비가 0.5:1 이었으며 이때 GaAs의 식각률은 ~2200${\AA}/min$ 이었으며 AlGaAs의 식각률은 ~4500${\AA}/min$ 이었다. 식각 후 표면의 RMS roughness은 < 2nm로 깨끗한 결과를 보여주었다. 15% $CF_4$ 가스가 혼합된 $17BCl_3/3CF_4$, 20W RIE power, 300W ICP source power, 7.5mTorr의 조건에서 3분 동안 공정한 결과 순수한 $BCl_3$ 플라즈마만을 사용한 경우보다 표면은 다소 거칠었지만 (RMS roughness: ~8.4) GaAs의 식각률 (~980nm/min)과 AlGaAs와 InGaP에 대한 GaAs의 선택도 (GaAs:AlGaAs=16:1, GaAs:InGaP=38:1)는 크게 증가하였다. 그리고 AlGaAs 및 InGaP의 경우 식각 시 나타난 휘발성이 낮은 식각 부산물 ($AlF_3:1300^{\circ}C$, $InF_3:1200^{\circ}C$)로 인하여 50nm/min 이하의 낮은 식각률을 보였고, 62.5%의 $CF_4$가 혼합된 $7.5BCl_3/12.5CF_4$플라즈마의 조건에서는 AlGaAs 및 InGaP에 대한 GaAs의 선택도가 각각 280:1, 250:1을 나타내었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.113-116
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• 2010

We report on the growth and characteristics of the structural and optical properties of InGaN nano-structures doped with antimony (Sb) as a catalyst. The use of catalyst has been explored to modify the growth and defect generation during strained layer heteroepitaxial growth. We performed the growth of the InGaN nano-structures on c-sapphire substrates using mixed-source hydride vapor phase epitaxy (HVPE). The characteristic of samples was measured by scanning electron microscope (SEM) and photoluminescence (PL). The aligning direction of c-axis of the InGaN nano-structures was changed from vertical to parallel or inclined to the surface of substrates when the Sb was added as a catalyst. The indium composition was estimated about 3.2% in both cases of with or without the addition of Sb in the InxGal-xN structures. From the results of InGaN nano-structures formed with the addition of Sb, we can expect the performance of optical devices would be more improved by reduced piezo-electric field if we use the InGaN nano-structures of which c-axes are aligned parallel to the substrates as an active layer.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.59-64
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• 2004

GaAs thin films were grown epitaxially by MOCVD method on (001) GaAs substrate. And as a surfactant, Bi(bismuth) thin films were deposited on GaAs buffer layer by using TMBi(trimethylbismuth) source. In-situ reflectance difference spectroscopy(RDS) was used to monitor the surface reconstruction of GaAs and Bi thin films. As the results, under the exposure of TBAs(tertiarybuthylarsine) and hydrogen atmosphere, the surface reconstruction of GaAs was changed from As-rich c($4{\times}4$) to As-rich ($2{\times}4$), which was due to the adsoption and desorption of As dimers. The first bismuth surface related RDS signal was reported. At the deposition temperature of $450^{\circ}C$, Bi-terminated GaAs surface showed the RDS spectrum similar to that of Sb-terminated GaAs surface, possibly a ($2{\times}4$) surface. And Bi surface layers were rapidly evaporated with increasing the deposition temperature($550^{\circ}C$), finally becoming As-terminated ($2{\times}4$) surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.77-78
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• 2006

We fabricated photonic crystals on GaAs and GaN substrates. After anodizing the aluminium thin film in electrochemical embient, the porous alumina was implemented to the mask for reactive ion beam etching process of GaAs wafer. And photonic crystals in GaN wafer were also fabricated using electron beam nano-lithography process. The coated PMMA thin film with 200 nm-thickness on GaN surface was patterned with triangular lattice and etched out the GaN surface by the inductively coupled plasma source. The fabricated GaAs and GaN photonic crystals provide the enhanced intensities of light emission for the wavelengths of 858 and 450 nm, respectively. We will present the detailed dimensions of photonic crystals from SEM and AFM measurements.