• Korean Journal of Materials Research
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• v.9 no.1
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• pp.42-45
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• 1999

The room temperature optical transmission spectra of GaN /InGaN/GaN single quantum wells (SQW) and InGaN/GaN heterostructures grwon by low pressure metalorganic chemical vapor deposition have been measured. The dependence of the absorption edges of the GaN/InGaN/GaN SQW on the well width has been determined from the transmission spectra. The result shows that the absorption edge of GaN/InGaN/GaN SQW shifts towards lower energy as increasing the well width. The dependence of the absorption edges of the InGaN/GaN heterostructures on InN mole fraction has also been determined from the transmission spectra. The result is compared with calculated values obtained from Vegards's laws. Our result shows a good agreement with the calculated values.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.8
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• pp.752-758
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• 2004

This paper reports on the DC and RF characteristics of AlGaN/InGaN/GaN high electron-mobility transistors (HEMTs) grown by molecular beau epitaxy(MBE) on sapphire substrates. The devices with a 0.5 ${\mu}$m gate-length exhibited relatively flat transconductance(g$\_$m/), which results from the enhanced carrier confinement of the InGaN channel. The maximum drain current was 880 mA/mm with a peak g$\_$m/ of 156 mS/mm, an f$\_$T/ of 17.3 GHz, and an f$\_$MAX/ or 28.7 GHz. In addition to promising DC and RF results, pulsed I-V and current-switching measurements showed little dispersion in the unpassivated AlGaN/InGaN HEMTs. These results suggest that the addition of In to the GaN channel improves the electron transport characteristics as well as suppressing current collapse that is related to the surface trap states.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.11
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• pp.29-34
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• 2004

This paper reports the RF dispersion and linearity characteristics of unpassivated AlGaN/InGaN/GaN high electron-mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE). The devices with a 0.5 ${\mu}{\textrm}{m}$ gate-length exhibited relatively good DC characteristics with a maximum drain current of 730 mA/mm and a peak g$_{m}$ of 156 mS/mm. Highly linear characteristic was observed by relatively flat DC transconductance (g$_{m}$) and good inter-modulation distortion characteristics, which indicates tight channel carrier confinement of the InGaN channel. Little current collapse in pulse I-V and load-pull measurements was observed at elevated temperatures and a relatively high power density of 1.8 W/mm was obtained at 2 GHz. These results indicate that current collapse related with surface states will not be a power limiting factor for the AlGaN/InGaN HEMTs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.3
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• pp.83-88
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• 2022

To improve the crystallinity of GaN, there are researches on surface treatment to control the difference in physical properties between GaN and heterogeneous substrate. 'Low-temperature GaN (LT-GaN)' is one of the ways to solve the problem and we investigated the relationship between growth temperature and properties of LT-GaN in our homemade vertical type HVPE. The LT-GaN nuclei were formed on the sapphire surface at low growth temperatures and they presented differences in the density and crystallinity depending on the growth temperature. Significantly, the stress relaxation effect on the epitaxial GaN (epi-GaN) was affected by the crystallinity of LT-GaN. However, the high crystallinity of LT-GaN exacerbated the crystal quality of epi-GaN because they worked as a catalyst and seed of polycrystalline.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.162-167
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• 2013

An epitaxial layer structure for heterojunction p-InGaP/N-InAlGaP solar cell has proposed. Simulation for current density-voltage characteristics has been performed on p-InGaP/N-InAlGaP structure and the simulation results were compared with p-InGaP/p-GaAs/N-InAlGaP structure and homogeneous InGaP pn junction structure. The simulation result showed that the maximum output power and fill factor have greatly increased by replacing n-InGaP with N-InAlGaP. The thicknesses of p-InGaP and n-InAlGaP were optimized for the epitaxial layer structure of p-InGaP/N-InAlGaP.

• Electronics and Telecommunications Trends
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• v.38 no.1
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• pp.36-45
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• 2023

The increasing demand for ultra-high efficiency of compact power conversion systems for electric vehicle applications has brought GaN power semiconductors to the fore due to their low conduction losses and fast switching speed. In particular, the development of materials and core device processes contributed to remarkable results regarding the publication of vertical GaN power devices with high breakdown voltage. This paper reviews recent advances on GaN material technology and vertical GaN power device technology. The GaN material technology covers the latest technological trends and GaN epitaxial growth technology, while the vertical GaN power device technology examines diodes, Trench FETs, JFETs, and FinFETs and reviews the vertical GaN PiN diode technology developed by ETRI.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.2
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• pp.123-129
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• 2001

The optimal high temperature processing conditions for the formation of Ohmic contact of Ti/Al/Pt/Au multiple layers were established for the fabrication of n$^{+}$-GaN/AlGaN/GaN HFET device. Contact resistivity as low as 3.4x10$^{-6}$ ohm-$\textrm{cm}^2$ was achieved by the annealing of the sample at 100$0^{\circ}C$ for 10 sec. using the RTA (Rapid Thermal Annealing) system. The fabricated HFET (Heterostructure Field Effect Transistor) with a structure of n'-GaN/undoped AlGaN/undoped GaN exhibited a low knee voltage of 3.5 V and a maximum source-drain current density of 180 mA/mm at Vg=0V.V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.96-99
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• 2003

본 논문에서는 수치 해석 방법을 이용하여 $In_{x}Ga_{1-x}N/GaN$ (x=0.06~0.1) 양자우물 구조의 에너지 준위를 계산하였다. InGaN 벌크 샘플(bulk sample)의 PL(photoluminescence) 데이터로부터 bowing factor를 결정한 후 InGaN의 유효 에너지 밴드갭을 계산하였고, InGaN/GaN 양자우물 구조의 전도대와 가전자대의 오프셋(offset)을 0.67/0.33으로 정하였다. 다음으로, 양자화 효과에 의한 에너지 변위와 압전장(piezoelectric field)을 제외한 양축 압축 변형(biaxial compressive strain)에 의한 에너지 변위를 고려하여 기저준위 전자와 heavy hole(le-1hh)간의 천이 에너지를 계산하였다. 계산된 천이 에너지는 PL로 측정한 천이 에너지에 비해 약 9~15 meV 크게 관찰되었는데, 이것은 InGaN/GaN 양자우물 계면에 발생하는 압전장 때문인 것으로 생각된다.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.93-95
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• 2012

We report on the growth and characterization of the nano- and micro scale GaN structures selectively grown on the vertex of GaN stripes using the metal organic vapor phase epitaxy method and conventional photolithography technique. The triangular shaped nano- and micro GaN structures which have semi-polar {11-22} facets were formed only on the vertex of the lower GaN stripes. Crystalline defects reduction was observed by transmission electron microscopy for upper GaN stripes. We also have grown the InGaN/GaN multi-quantum well structures on the semi-polar facets of the upper GaN stripes. Cathodoluminescence images were taken at 366, 412 and 555 nm related to GaN band edge, InGaN/GaN layer and defects, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.233-236
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• 2012

In this paper, the output characteristics of GaN-based LED considering blocking layer design variables are analyzed. The basic structure of the LED consists of active region of GaN barrier and InGaN quantum well between AlGaN EBL(Electron Blocking Layer) and AlGaN HBL(Hole Blocking Layer) on GaN buffer layer. The output power, internal quantum efficiency characteristics of LED active region considering Al mole fraction of EBL, thickness of EBL, Al mole fraction of HBL and doping concentration of HBL are analyzed using ISE-TCAD.