• 한국전기전자재료학회논문지
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• 제23권9호
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• pp.671-675
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• 2010

Gallium nitride (GaN), wide bandgap semiconductor, has attracted much attention because they are projected to have much better performance than silicon. In this paper, effects of design parameters change of GaN power static induction transistor (SIT) on the electrical characteristics (breakdown voltage, on resistance) were analyzed by computer simulation. According to the analyzed results, the optimization was performed to get power GaN SIT that has 600 V class breakdown voltage. As a result, we could get optimized 600 V class power GaN SIT that has higher breakdown voltage and lower On resistance with a thin (a several micro-meters) thickness of the channel layer.

• 전자통신동향분석
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• 제29권6호
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• pp.53-62
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• 2014

본고는 최근 화두가 되고 있는 에너지 절감을 위해 고효율, 친환경의 WBG(Wide Band-Gap) 화합물반도체인 SiC(Silicon Carbide), GaN(Gallium Nitride) 전력반도체 소자 및 전력변환 모듈의 기술동향과 ETRI에서 연구개발 진행 중인 GaN 전력반도체 관련 기술에 대해 기술한다. WBG 전력반도체는 기존의 실리콘 전력반도체와 비교하여 열 특성 향상, 고속 스위칭, 고전압/고전류 특성 및 스위칭 손실 최소화 등이 가능하고 이에 따른 시스템의 소형화 및 전력효율 향상 효과를 얻을 수 있다. 특히, GaN 전력반도체 소자는 시장이 가장 넓게 형성되어 있는 900V 이하에 적용이 가능하며, 앞으로 시장이 커질 것으로 예상되는 HEV(Hybrid Electric Vehicle)/EV(Electric Vehicle)의 친환경 자동차에도 활용될 것으로 기대되고 있다. 본고는 최근의 일본과 미국에서의 WBG 전력반도체에 대한 관심 및 투자 방향과 GaN 전력반도체 소자에 대한 해외 기업의 업계동향에 대해서도 함께 살펴본다. 이러한 WBG 전력반도체에 대한 해외 선진업체의 산업동향과 더불어 ETRI에서 연구개발 중인 GaN 전력반도체 기술현황에 대해 전력소자 설계 및 제조공정, 패키징, 전력모듈 설계 제작 기술을 포함하여 기술한다.

• 한국전기전자재료학회논문지
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• 제15권7호
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• pp.564-569
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• 2002

Heteroepitaxial GaN films were grown on sapphire substrates in order to study the effects of the buffer layer's surface roughness and thermal treatment on the epitaxial layer's quality. For this, GaN buffer layers were grown at $550^{\circ}C$ with various TMGa flow rates and durations of growth, and annealed at $1010^{\circ}C$ for 3 min after the temperature was raised by 23 ~ $92^{\circ}C/min$, and then GaN epitaxial layers were grown at $1000^{\circ}C$. It has been found that the buffer layer's surface roughness and the thermal treatment condition are critical factors on the quality of the epitaxial layer. When a buffer layer was frown with a TMGa flow rate of $24\mu mole/min$ for 30 sec, the surface roughness of the buffer lather was minimum and when the thermal ramping rate was $30.6^{\circ}C/min$ on this layer, the successively grown epitaxial layer's crystalline and optical qualities were optimized with a specular morphology. The minimum full width at half maximum(FWHM) of GaN(0002) x-ray diffraction peak and that of near-band-edge(NBE) peak from a room temperature photoluminescence (PL) were 5 arcmin and 9 nm, respectively.

• 전력전자학회논문지
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• 제22권4호
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• pp.297-304
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• 2017

The purpose of this paper is to analyze losses because of switching devices and the secondary side circuit diodes of 500 W full bridge dc-dc converter by applying gallium nitride (GaN) field-effect transistor (FET), which is one of the wide band gap devices. For the detailed device analysis, we translate the specific resistance relation caused by the GaN FET material property into algebraic expression, and investigate the influence of the GaN FET structure and characteristic on efficiency and system specifications. In addition, we mathematically compare the diode rectifier circuit loss, which is a full bridge dc-dc converter secondary side circuit, with the synchronous rectifier circuit loss using silicon metal-oxide semiconductor (Si MOSFET) or GaN FET, which produce the full bridge dc-dc converter analytical value validity to derive the final efficiency and loss. We also design the heat sink based on the mathematically derived loss value, and suggest the heat sink size by purpose and the heat divergence degree through simulation.

• Current Photovoltaic Research
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• 제8권2호
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• pp.50-53
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• 2020

GaN based photoelectrode has shown good potential owing to its better chemical stability and tunable bandgap with materials such as InN and AlN. Tunable bandgap allows GaN to make the maximum utilization of solar spectrum, which could improve photoelectrode performance. However, the problems about low photoelectrode performance and photo-corrosion still remain. In this study, we attempt to investigate the photoelectrochemical (PEC) properties of phosphor application to InGaN photoelectrode. Experimental result shows YAG:Ce³⁺ and beta-SiALON phosphor result in the highest photoelectrode performance of InGaN.

• 한국전자파학회논문지
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• 제24권4호
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• pp.394-402
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• 2013

본 논문은 GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor)를 이용한 S대역 레이더용 전력증폭기 설계하고 제작된 스위칭 모드 전력증폭기의 ruggedness 시험에 관련된 내용을 기술하였다. 고효율 특성을 위해 전력증폭기를 Class-F로 설계하였으며, 측정을 위한 입력 신호는 $100{\mu}s$의 pulse width 및 10 %의 duty cycle인 pulse 신호를 사용하였다. 제작된 Class-F 전력증폭기의 중심 주파수에서 측정한 결과, 8.7 dB의 전력 이득과 42 dBm의 출력 전력, 54.2 %의 전력 부가 효율(PAE) 및 62.6 %의 드레인 효율이 측정되었다. 또한, 전력증폭기의 신뢰성 시험의 일환으로 Ruggedness 시험을 위한 실험 구성을 제안하고, VSWR(Voltage Standing Wave Ratio)을 변화시켜 출력 전력과 효율을 측정하였다. 설계된 전력증폭기가 VSWR 변화에 따라 출력 전력 32.6~41.1 dBm까지 변화하고, 드레인 효율은 23.4~63 %까지 변하는 특성을 얻을 수 있었다.

• 센서학회지
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• 제31권4호
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• pp.271-277
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• 2022

We analyzed the effects of the interface trap on the output characteristics of an inversion mode n-channel GaN Schottky barrier (SB)-MOSFET based on the N_it distribution using TCAD simulation. As interface trap number density (N_it) increased, the threshold voltage increased while the drain current density decreased. Under N_it=5.0×10¹⁰ cm^-2 condition, the threshold voltage was 3.2 V for V_DS=1 V, and the drain current density reduced to 2.4 mA/mm relative to the non-trap condition. Regardless of the N_it distribution type, there was an increase in the subthreshold swing (SS) following an increase in N_it. Under U-shaped N_it distribution, it was confirmed that the SS varied depending on the gate voltage. The interface fixed charge (Q_f) caused an shift in the threshold voltage and increased the off-state current collectively with the surface trap. In summary, GaN SB-MOSFET can be a building block for high power UV optoelectronic circuit provided the surface state is significantly reduced.

• ETRI Journal
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• 제30권1호
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• pp.158-160
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• 2008

A highly linear and efficient GaN HEMT Doherty amplifier for wideband code division multiple access (WCDMA) repeaters is presented. For better performance, the adaptive gate bias control of the peaking amplifier using the power tracking circuit and the shunt capacitors is employed. The measured one-carrier WCDMA results show an adjacent channel leakage ratio of -43.2 dBc at ${\pm}2.5$-MHz offset with a power added efficiency of 40.1% at an average output power of 37 dBm, which is a 7.5 dB back-off power from the saturated output power.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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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.

• 한국재료학회지
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• 제17권5호
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• pp.273-277
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• 2007

Vertically aligned Zinc Oxide rod arrays were grown by the self-assembly hydrothermal process on the GaN epitaxial layer which has a same lattice structure with ZnO. Zinc nitrate and DETA solutions are used in the hydrothermal process. The $(HfO_2)$ thin film was deposited on GaN and the patterning was made by the photolithography technique. The selective growth of ZnO rod was achieved with the patterned GaN substrate. The fabricated ZnO rods are single crystal, and have grown along hexagonal c-axis direction of (002) which is the same growth orientation of GaN epitaxial layer. The density and the size of ZnO rod can be controlled by the pattern. The optical property of ordered array of vertical ZnO rods will be discussed in the present work.