• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.321-324
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• 2020

In this work, we developed a selective etching process for GaN that is a key process in p-GaN/AlGaN/GaN enhancement-mode (E-mode) power switching field-effect transistor (FET) fabrication. In order to achieve a high current density of p-GaN/AlGaN/GaN E-mode FET, the p-GaN layer beside the gate region must be selectively etched whereas the underneath AlGaN layer should be maintained. A selective etching process was implemented by oxidizing the surface of the AlGaN layer and the GaN layer by adding O2 gas to Cl2/N2 gas which is generally used for GaN etching. A selective etching process was optimized using Cl2/N2/O2 gas mixture and a high selectivity of 53:1 (= GaN/AlGaN) was achieved.

• Journal of the Korean Institute of Navigation
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• v.15 no.3
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• pp.99-106
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• 1991

In order to grow InGaAsP epitaxial layer on GaAs by LPE, an accurate phase diagram for In-Ga-As-P quarternary compounds is required. But the short wavelength InGaAsP/GaAs phase diagram for full wavelength range was not yet reported. In this study, therefore, a theoretical calculation has been carried out by using thermodynamic's equation for InGaAsP/GaAs in order to get the relation between the mole fraction of the sloute and solid phase compounds. And the calculation being compared with the dta of Kawanishi et. al, the result has been shown that his phase diagram obtained by the calculation can apply to growing InGaAsP/GaAs by LPE.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.209.1-209.1
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• 2013

GaP는 가시광선 발광다이오드을 얻을 수 있는 적절한 재료중의 하나로 해당영역의 파장에 대하여 높은 양자효율을 얻을 수 있고, 깊은 준위 재결합이 없기 때문에 GaP 녹색 및 As 첨가한 GaAsP 적색 LED 에 적용할 수 있습니다. 또한, 상온에서 2.2 eV 에 해당하는 넓은 에너지 밴드갭을 가지고 있으므로, 소음이 없는 자외선 검출기에도 적합합니다. 이 물질에 대한 소자들은 기존에 GaP 기판을 사용하였습니다. 최근, GaP 와 격자상수가 비슷한 Si 기판을 활용하여 그 위에 성장하는 방법에 대한 관심이 많아졌습니다. Si는 물리적 및 화학적으로 안정하고 딱딱한 소재이며 대면적 기판을 쉽게 얻을 수 있어 전자 기기 및 대규모 집적 회로의 좋은 소재입니다. Si 와 대조적으로 GaP은 깨지기 쉬운 재료이며 GaP 기판은 Si와 같은 대면적 기판을 얻을 수 없습니다. 이러한 문제의 한 가지 해결책은 Si 기판위에 GaP 층의 성장입니다. GaP 과 Si의 조합은 현재의 광전소자 들에 더하여 더 많은 응용프로그램들을 가능하게 할 것입니다. 그러나, Si 기판위에 GaP 성장 시 삼차원적 성장 및 역위상 경계면과 같은 문제점들이 발생하므로 질이 높고 균일한 결정의 GaP 를 얻기가 어렵습니다. 따라서, Si 에 GaP 의 성장시 초기 단계를 제어하는 성장 기술이 필요합니다. 본 연구에서는, 유기금속화학증착법을 이용하여 Si 기판위에 양질의 GaP를 얻을 수 있는 최적의 성장조건을 얻고자 합니다. 실험 조건은 Si에 GaP의 에피택셜 성장의 초기 단계에 영향을 주는 V/III 비율, 성장압력, 기판방향 등을 가변하는 조건으로 진행하였습니다. V/III 비율은 100~6400, 성장 압력은 76~380 Torr로 진행하였고, Si 기판은 just(001)과 2~6도 기울어진 (001) 기판을 사용하였습니다.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.655-660
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• 2001

Surface photovoltage spectroscopy was used to study $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P/GaAs$ grown by metalorganic chemical vapor deposition(MOCVD). Energy gap related transition in GaAs and $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P$ were observed. By measuring the frequency dependence of $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P/GaAs$, we observed that SPV line shape does not chance, whereas the amplitude change. This results is due to the difference in the lifetimes of the photocarriers in GaAs and in $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P$. We also have evaluated the parameters that describe the temperature dependences of the band gap.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.207-210
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• 2001

Metal-organic VPE (MOVPE) epitaxial growth procedure and related device fabrication technique are reported for GaInP-based epitaxial materials and devices. For GaInP/GaInAs two-dimensional electron-gas field-effect transistor (TEGFET), a promising epitaxial stacking structure resulting in enhanced electron mobility is given. In conjunction with this, a new device fabrication technique to improve luminous intensity of GaInP-based LED is also shown.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.297-297
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• 2011

일반적으로 고출력 반도체 레이저 다이오드는 발진 파장 및 광출력에 따라 다양한 분야에 응용되고 있으며, 특히 발진파장이 808 nm 대역인 고출력 레이저 다이오드의 경우 재료가공, 펌핌용 광원, 의료 분야 등 다양한 응용분야를 가진 광원 중의 하나라고 할 수 있다. 808 nm 대역의 레이저 다이오드 제작에는 현재 InGaAsP/InGaP/GaAs 및 InGaAlAs/GaAs 양자우물을 이용하여 제작되고 있으나 양자우물과 이를 둘러싸는 장벽물질간의 band-offset이 적어 효율적인 고출력 레이저 다이오드의 제작에 다소 어려움이 있기 때문에 강한 캐리어 구속 효과를 지니는 양자점 혹은 양자대쉬 구조를 사용하는 것이 고출력 레이저 다이오드를 제작할 수 있는 한 방법이다. 실험에 사용된 InP/InGaP 양자구조는 Riber사의 compact21 MBE 장치를 사용하여 성장하였으며 GaAs기판을 620-630도에서 가열하여 표면의 산화층을 제거하고 580도에서 약 100 nm 두께의 GaAs 버퍼층 및 50 nm 두께의 InGaP층을 성장하였다. 양자 구조는 MEE (migration enhanced epitaxy) 방식으로 성장되었는데, 이는 InP/InGaP 의 lattice mismatch율이 작아 양자 구조 형성이 어렵기 때문에 InP/InGaP 양자 구조 성장에 적합하다고 생각하였으며, Indium 2초, growth interuption time 10초, phosphorous 2초 그리고 growth interuption time 10초를 하나의 시퀀스로 보고, 그 시퀀스를 반복하여 양자 구조를 성장하였다. 본 실험에 사용된 P 소스는 Riber사의 KPC-250 P-valved cracker모델을 사용하였으며 InP의 성장률은 0.985${\AA}/s$이다. InP/InGaP 양자구조 성장 중에, 성장 온도, 시퀀스 수의 변화 등 다양한 조건을 변화 시켜 샘플을 성장시켰고, 양자 구조 성장을 확인하기 위하여 AFM 및 SEM을 통해 구조적 분석을 하였으며 PL 측정을 통해 광학적 분석을 진행하였다.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.421-426
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• 1999

In this paper, we present p-channel GaAs MOSFET having $Al_2O_3$ as gate insulator fabricated on a semi-insulating GaAs substrate, which can be operated in the depletion mode. $1\;{\mu}m$ thick undoped GaAs buffer layer, $4000\;{\AA}$ thick p-type GaAs epi-layer, undoped $500{\AA}$ thick AlAs layer, and $50\;{\AA}$ thick GaAs cap layer were subsequently grown by molecular beam epitaxy(MBE) on (100) oriented semi-insulating GaAs substrate and this wafer was oxidized. AlAs layer was fully oxidized as a $Al_2O_3$ thin film. The I-V, $g_m$, breakdown charateristics of the fabricated GaAs MOSFET showed that wet thermal oxidation of AlAs/GaAs epilayer/S I GaAs was successful in realizing depletion mode p-channel GaAs MOSFET.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.29.1-29.1
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• 2009

Fabrication of good quality P-type GaN remained as a challenge for many years which hindered the III-V nitrides from yielding visible light emitting devices. Firstly Amano et al succeeded in obtaining P-type GaN films using Mg doping and post Low Energy Electron Beam Irradiation (LEEBI) treatment. However only few region of the P-GaN was activated by LEEBI treatment. Later Nakamura et al succeeded in producing good quality P-GaN by thermal annealing method in which the as deposited P-GaN samples were annealed in N2 ambient at temperatures above $600^{\circ}C$. The carrier concentration of N type and P-type GaN differs by one order which have a major effect in AlGaN based deep UV-LED fabrication. So increasing the P-type GaN concentration becomes necessary. In this study we have proposed a novel method of activating P-type GaN by electrochemical potentiostatic method. Hydrogen bond in the Mg-H complexes of the P-type GaN is removed by electrochemical reaction using KOH solution as an electrolyte solution. Full structure LED sample grown by MOCVD serves as anode and platinum electrode serves as cathode. Experiments are performed by varying KOH concentration, process time and applied voltage. Secondary Ion Mass Spectroscopy (SIMS) analysis is performed to determine the hydrogen concentration in the P-GaN sample activated by annealing and electrochemical method. Results suggest that the hydrogen concentration is lesser in P-GaN sample activated by electrochemical method than conventional annealing method. The output power of the LED is also enhanced for full structure samples with electrochemical activated P-GaN. Thus we propose an efficient method for P-GaN activation by electrochemical reaction. 30% improvement in light output is obtained by electrochemical activation method.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.219-219
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• 2013

The effect of an electron blocking layer (EBL) on V-I curves in GaN/InGaN multiple quantum well is investigated. For the first time, we found that curves were intersected at 3.012 V and analyzed the reason for intersection. The forward voltage in LEDs with an p-AlGaN EBL is larger than without p-AlGaN EBL at low injection current because the Mg doping efficiency for p-GaN layer was higher than that of p-AlGaN layer. However, the forward voltage in LEDs with an p-AlGaN EBL is smaller than without p-AlGaN EBL at high injection current because the carriers overflow from the active layer when injection current increases in LEDs without p-AlGaN EBL and in case of LED with p-AlGaN EBL, the carriers are blocked by EBL.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.206-214
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• 1993

Coherent precipitation of Zn3P2 during Zn diffusion in a GaInAsP/InP heterostructure was studied using high-resolution transmission electron microscopy. Zn-diffusion-induced intermixing of Ga and In across the GaInAsP/InP heterointerface provided a Ga-mixed InP region which was nearly lattice-matched with Zn3P2 crystal and thus allowed thecoherent precipitation of Zn3P2. The Zn3P2 precipitates were preferentially nucleated at stacking faults which were formed to relax interfacial strain built up by the intermixing. The precipitates were grown to planar epitaxial layer along (100) plane in the lattice-matched region. The TEM images and diffraction pettern revealed that the tetragonal Zn3P2 crystals were coherently matched to the fcc structured GaInP matrix by the {{{{ SQRT {2} $\times$ SQRT {2} $\times$2 }} arrangement. The precipitation reaction of Zn3P2 was explained by an atomic migration model based on the kick-out mechanism.