Faculty Profiles - HONDA, Yoshio

Dielectric Ruduced Surface Field Effect on Vertical GaN-on-GaN Nanowire Schottky Barrier Diodes

Liao Yaqiang, Chen Tao, Wang Jia, Ando Yuto, Yang Xu, Watanabe Hirotaka, Hirotani Jun, Kushimoto Maki, Deki Manato, Tanaka Atsushi, Nitta Shugo, Honda Yoshio, Chen Kevin J., Amano Hiroshi

PROCEEDINGS OF THE 2020 32ND INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES AND ICS (ISPSD 2020) page： 349 - 352 2020

Two-dimensional analysis of the nonuniform quantum yields of multiple quantum wells for AlGaN-based deep-ultraviolet LEDs grown on AlN templates with dense macrosteps using cathodoluminescence spectroscopy

Nagasawa Yosuke, Sugie Ryuichi, Kojima Kazunobu, Hirano Akira, Ippommatsu Masamichi, Honda Yoshio, Amano Hiroshi, Akasaki Isamu, Chichibu Shigefusa F.

JOURNAL OF APPLIED PHYSICS Vol. 126 ( 21 ) 2019.12

Direct evidence of Mg diffusion through threading mixed dislocations in GaN p-n diodes and its effect on reverse leakage current International journal

Usami Shigeyoshi, Mayama Norihito, Toda Kazuya, Tanaka Atsushi, Deki Manato, Nitta Shugo, Honda Yoshio, Amano Hiroshi

APPLIED PHYSICS LETTERS Vol. 114 ( 23 ) 2019.6

Correlation between nanopipes formed from screw dislocations during homoepitaxial growth by metal-organic vapor-phase epitaxy and reverse leakage current in vertical p-n diodes on a free-standing GaN substrates International journal

Usami Shigeyoshi, Tanaka Atsushi, Fukushima Hayata, Ando Yuto, Deki Manato, Nitta Shugo, Honda Yoshio, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 2019.6

Effect of photoelectrochemical etching and post-metallization annealing on gate controllability of AlGaN/GaN high electron mobility transistors International journal

Uemura Keisuke, Deki Manato, Honda Yoshio, Amano Hiroshi, Sato Taketomo

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 2019.6

Deeply and vertically etched butte structure of vertical GaN p-n diode with avalanche capability International journal

Fukushima Hayata, Usami Shigeyoshi, Ogura Masaya, Ando Yuto, Tanaka Atsushi, Deki Manato, Kushimoto Maki, Nitta Shugo, Honda Yoshio, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 2019.6

Electronic structure analysis at threading dislocation and at m-plane surface of nanopipes in GaN thin films

Nakano Takashi, Chokawa Kenta, Araidai Masaaki, Shiraishi Kenji, Oshiyama Atsushi, Usami Shigeyoshi, Kusaba Akira, Kangawa Yoshihiro, Tanaka Atsushi, Honda Yoshio, Amano Hiroshi

JSAP Annual Meetings Extended Abstracts Vol. 2019.1 ( 0 ) page： 3122 - 3122 2019.2

Electronic structure analysis of core structures of threading dislocations in GaN

Nakano, T; Chokawa, K; Araidai, M; Shiraishi, K; Oshiyama, A; Kusaba, A; Kangawa, Y; Tanaka, A; Honda, Y; Amano, H

2019 COMPOUND SEMICONDUCTOR WEEK (CSW) page： . 2019

Analysis of Cesium Layer on InGaN by Temperature Programmed Desorption Method

Kashima Masahiro, Daiki Sato, Atsushi Koizumi, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano, Hokuto Iijima, Takashi Meguro

JSAP Annual Meetings Extended Abstracts Vol. 2018.1 ( 0 ) page： 1670 - 1670 2018.3

Electrical and Thermal Analysis of Vertical GaN-on-GaN PN Diodes

Yates, L; Pavlidis, G; Graham, S; Usami, S; Nagamatsu, K; Honda, Y; Amano, H

PROCEEDINGS OF THE 17TH IEEE INTERSOCIETY CONFERENCE ON THERMAL AND THERMOMECHANICAL PHENOMENA IN ELECTRONIC SYSTEMS (ITHERM 2018) page： 831 - 837 2018

Effect of thermal treatment on the quantu efficiency of NEA-InGaN photocatode

Kashima Masahiro, Iijima Hokuto, Nishitani Tomohiro, Sato Daiki, Honda Yoshio, Amano Hiroshi, Meguro Takashi

JSAP Annual Meetings Extended Abstracts Vol. 2017.1 ( 0 ) page： 1554 - 1554 2017.3

A Study on the Photo-resistance and the Decomposition Mechanism of Perfluoro Resins Applied to Encapsulating Deep Ultra Violet LEDs

Nagasawa Yosuke, Yamada Kiho, Nagai Shouko, Hirano Akira, Ipponmatsu Masamichi, Aosaki Ko, Honda Yoshio, Amano Hiroshi, Akasaki Isamu

JSAP Annual Meetings Extended Abstracts Vol. 2017.1 ( 0 ) page： 1136 - 1136 2017.3

Fabrication and Electric Characteristics Evaluation of GaN-MIS Capacitor with BN

Matsushita Junya, Nagamatsu Kentarou, Yang Xu, Tanaka Atushi, Kushimto Maki, Deki Manato, Nitta Shugo, Honda Yoshio, Amano Hiroshi

JSAP Annual Meetings Extended Abstracts Vol. 2016.2 ( 0 ) page： 2888 - 2888 2016.9

Electroluminescence Pattern Investigation of the PIN Diode on GaN Substrate

Usami Shigeyoshi, Ando Yuto, Tanaka Atsushi, Nagamatsu Kentaro, Kushimoto Maki, Deki Manato, Nitta Shugo, Honda Yoshio, Amano Hiroshi

JSAP Annual Meetings Extended Abstracts Vol. 2016.2 ( 0 ) page： 2867 - 2867 2016.9

Evaluation of excess In during metal organic vapor-phase epitaxy growth of InGaN by monitoring via in situ laser scattering Reviewed

Honda Yoshio

Japanese Journal of Applied Physics Vol. 55 2016

Growth of semipolar (1-101) high-indium-content InGaN quantum wells using InGaN tilting layer on Si(001) Reviewed

Honda Yoshio

Japanese Journal of Applied Physics Vol. 55 2016

HVPE and VLS-HVPE synthesis of vertical and horizontal GaN nanowires

Lekhal Kaddour, Mitsunari Tadashi, Honda Yoshio, Amano Hiroshi

JSAP Annual Meetings Extended Abstracts Vol. 2014.2 ( 0 ) page： 1745 - 1745 2014.9

Characteristics of a-plane GaN films grown on optimized silicon-dioxide-patterned r-plane sapphire substrates

Son Ji-Su, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi, Baik Kwang Hyeon, Seo Yong Gon, Hwang Sung-Min

THIN SOLID FILMS Vol. 546 page： 108 - 113 2013.11

Effects of exciton localization on internal quantum efficiency of InGaN nanowires

Murotani Hideaki, Yamada Yoichi, Tabata Takuya, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JOURNAL OF APPLIED PHYSICS Vol. 114 ( 15 ) 2013.10

Fabrication of InGaN/GaN Multiple Quantum Wells on (1(1)over-bar01) GaN

Tanikawa Tomoyuki, Sano Tomotaka, Kushimoto Maki, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

High Internal Quantum Efficiency Blue-Green Light-Emitting Diode with Small Efficiency Droop Fabricated on Low Dislocation Density GaN Substrate

Sano Tomotaka, Doi Tomohiro, Inada Shunko Albano, Sugiyama Tomohiko, Honda Yoshio, Amano Hiroshi, Yoshino Takashi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Growth of GaN on Si(111) Substrates via a Reactive-Sputter-Deposited AlN Intermediate Layer

Yamada Takaya, Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

GaN Nanowires Grown on a Graphite Substrate by Radio Frequency Molecular Beam Epitaxy

Nakagawa Shinta, Tabata Takuya, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Stacking Faults and Luminescence Property of InGaN Nanowires

Tabata Takuya, Paek Jihyun, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Thick InGaN Growth by Metal Organic Vapor Phase Epitaxy with Sputtered InGaN Buffer Layer

Ohata Toshiya, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Strain-Compensated Effect on the Growth of InGaN/AlGaN Multi-Quantum Well by Metalorganic Vapor Phase Epitaxy

Doi Tomohiro, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Effects of Nano- and Microscale SiO2 Masks on the Growth of a-Plane GaN Layers on r-Plane Sapphire

Son Ji-Su, Miao Cao, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi, Seo Yong Gon, Hwang Sung-Min, Baik Kwang Hyeon

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Growth Mode and Threading Dislocation Behavior of GaN Films Grown on Patterned Sapphire Substrate with Radial Stripe Pattern

Okuno Koji, Oshio Takahide, Shibata Naoki, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

Emission Wavelength Dependence of Internal Quantum Efficiency in InGaN Nanowires

Murotani Hideaki, Andoh Hiroya, Tsukamoto Takehiko, Sugiura Toko, Yamada Yoichi, Tabata Takuya, Honda Yoshio, Yamaguchi Masatoshi, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 52 ( 8 ) 2013.8

I-1-2 Epitaxial growth of Ill-nitride by molecular beam epitaxy using high density radical source

KAWAI Yohjiro, HONDA Yoshio, YAMAGUCHI Masahito, AMANO Hiroshi, KONDO Hiroki, HIRAMATSU Mineo, KANO Hiroyuki, YAMAKAWA Kouji, DEN Shouji, Hori Masaru

The Proceedings of the Conference on Information, Intelligence and Precision Equipment : IIP Vol. 2013 ( 0 ) page： 5 - 7 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

Although plasma-assisted molecular beam epitaxy(PA-MBE) is a promising technique for GaN growth,the growth rate obtained by this technique is lower than that obtained by metal organic vapor phase epitaxy(MOVPE).In order to improve the growth rate of the technique,high density radical source(HDRS) was developed.By vacuum ultraviolet absorption spectroscopy(VUVAS) measurement,two orders of magnitude higher radical density was confirmed in a comparison of the HDRS and a conventional radical source(CRS).While faster growth rate of 1.4μm/h in GaN homoepitaxy was achieved,better crystalline quality of InxGa_<(1-x)>N(x=0.03〜0.16) epilayers with approximately 1.4μm thickness were also achieved by introducing the HDRS in PA-MBE.

DOI： 10.1299/jsmeiip.2013.5

Polarization properties in InGaN/GaN multiple quantum well on semipolar(1-101)GaN/Si

KUSHIMOTO Maki, TANIKAWA Tomoyuki, HONDA Yoshio, YAMAGUCHI Masahito, AMANO Hiroshi

IEICE technical report. Component parts and materials Vol. 112 ( 33 ) page： 15 - 18 2012.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We grew high-quality semipolar (1-101) GaN stripes on a Si substrate by selective area growth and regrew InGaN/GaN MQW on these stripes with MOVPE. The PL peak wavelength at 300 K and InGaN well thickness for the obtained samples were 435-590 nm and 2-9 nm, respectively. In PL measurements from the surface, we found that a shorter wavelength and thinner well sample have PL polarization perpendicular to the c axis. On the other hand, as the PL wavelength is longer and/or the well is thicker, the PL polarization shifts from perpendicular to parallel. In the PL measurement from the (11 -22) edge surface of the sample with shorter wavelength, we observed the narrowing of PL spectrum. In addition, the parallel component of PL polarization increased with increase in well thickness. Therefore, we can control the direction of polarization by managing well thickness and indium composition and apply to make a LD structure.

Strain relaxation in thick ($1{\bar {1}}01$) InGaN grown on GaN/Si substrate

Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi, Sawaki Nobuhiko

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 249 ( 3 ) page： 468 - 471 2012.3

Enhancement of two-dimensional electron gases in AlGaN-channel high-electron-mobility transistors with AlN barrier layers

Hashimoto Shin, Akita Katsushi, Yamamoto Yoshiyuki, Ueno Masaki, Nakamura Takao, Takeda Kenichiro, Iwaya Motoaki, Honda Yoshio, Amano Hiroshi

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE Vol. 209 ( 3 ) page： 501 - 504 2012.3

Impurity incorporation in semipolar (1-1 0 1) GaN grown on an Si substrate

Sawaki Nobuhiko, Hagiwara Kiyotaka, Hikosaka Toshiki, Honda Yoshio

SEMICONDUCTOR SCIENCE AND TECHNOLOGY Vol. 27 ( 2 ) 2012.2

Crystal Growth of Semipolar GaN on Si Substrate(<Special Issue>Breakthrough in Nitride Crystal Growth for Next Generation Devices)

Honda Yoshio

Journal of the Japanese Association for Crystal Growth Vol. 38 ( 4 ) page： 241 - 248 2012

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japanese Association for Crystal Growth

(1-101) GaN and (11-22) GaN was grown by MOVPE on etched Si substrate. A characteristic of optical, electrical and impurity was evaluated on each face GaN. We also reported an Indium incorporation and a process of dislocation propagation on the (1-101) GaN in this paper.

DOI： 10.19009/jjacg.38.4_241

Improvement of Light Extraction Efficiency for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

Inazu Tetsuhiko, Fukahori Shinya, Pernot Cyril, Kim Myung Hee, Fujita Takehiko, Nagasawa Yosuke, Hirano Akira, Ippommatsu Masamichi, Iwaya Motoaki, Takeuchi Tetsuya, Kamiyama Satoshi, Yamaguchi Masahito, Honda Yoshio, Amano Hiroshi, Akasaki Isamu

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 50 ( 12 ) 2011.12

AlGaN-Based Deep Ultraviolet Light-Emitting Diodes Fabricated on Patterned Sapphire Substrates

Kim Myunghee, Fujita Takehiko, Fukahori Shinya, Inazu Tetsuhiko, Pernot Cyril, Nagasawa Yosuke, Hirano Akira, Ippommatsu Masamichi, Iwaya Motoaki, Takeuchi Tetsuya, Kamiyama Satoshi, Yamaguchi Masahito, Honda Yoshio, Amano Hiroshi, Akasaki Isamu

APPLIED PHYSICS EXPRESS Vol. 4 ( 9 ) 2011.9

Effect of lateral vapor phase diffusion during the selective growth of InGaN/GaN MQW on semipolar and nonpolar GaN stripes

Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE Vol. 208 ( 5 ) page： 1175 - 1178 2011.5

Optical properties of (1 (1)over-bar 0 1) semi-polar InGaN/GaN multiple quantum wells grown on patterned silicon substrates

Chiu Ching-Hsueh, Lin Da-Wei, Lin Chien-Chung, Li Zhen-Yu, Chen Yi-Chen, Ling Shih-Chun, Kuo Hao-Chung, Lu Tien-Chang, Wang Shing-Chung, Liao Wei-Tsai, Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

JOURNAL OF CRYSTAL GROWTH Vol. 318 ( 1 ) page： 500 - 504 2011.3

Reduction of Efficiency Droop in Semipolar (1(1)over-bar01) InGaN/GaN Light Emitting Diodes Grown on Patterned Silicon Substrates (vol 4, 012105, 2011)

Chiu Ching-Hsueh, Lin Da-Wei, Lin Chien-Chung, Li Zhen-Yu, Chang Wei-Ting, Hsu Hung-Wen, Kuo Hao-Chung, Lu Tien-Chang, Wang Shing-Chung, Liao Wei-Tsai, Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

APPLIED PHYSICS EXPRESS Vol. 4 ( 3 ) 2011.3

Drastic Reduction of Dislocation Density in Semipolar (11(2)over-bar2) GaN Stripe Crystal on Si Substrate by Dual Selective Metal-Organic Vapor Phase Epitaxy

Murase Tasuku, Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi, Sawaki Nobuhiko

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 50 ( 1 ) 2011.1

Semi-polar GaN LEDs on Si substrate

Sawaki Nobuhiko, Honda Yoshio

SCIENCE CHINA-TECHNOLOGICAL SCIENCES Vol. 54 ( 1 ) page： 38 - 41 2011.1

Reduction of Efficiency Droop in Semipolar (1(1)over-bar01) InGaN/GaN Light Emitting Diodes Grown on Patterned Silicon Substrates

APPLIED PHYSICS EXPRESS Vol. 4 ( 1 ) 2011.1

Raman Spectroscopic Study Of Residual Strain In (1-101) GaN And (0001) GaN Layers Grown On Si Substrate

Sugiura Toko, Kim Eun-Hee, Honda Yoshio, Takagi Hiroyuki, Tsukamoto Takehiko, Andoh Hiroya, Yamaguchi Masahito, Sawaki Nobuhiko

PHYSICS OF SEMICONDUCTORS: 30TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS Vol. 1399 2011

Achieving high-growth-rate in GaN homoepitaxy using high-density nitrogen radical source Reviewed

Kawai Yohjiro, Chen Shang, Honda Yoshio, Yamaguchi Masahito, Amano Hiroshi, Kondo Hiroki, Hiramatsu Mineo, Kano Hiroyuki, Yamakawa Koji, Den Shoji, Hori Masaru

PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 8, NO 7-8 Vol. 8 ( 7-8 ) 2011

Raman spectroscopic study of residual strain and stress in GaN layer grown on Si substrates

Touko SUGIURA, Yoshio HONDA, Akihiro OKAMOTO, Hiroyuki TAKAGI, Takehiko TSUKAMOTO, Hiroya ANDOH

Journal of National Institute of Technology, Toyota College Vol. 42 ( 0 ) page： 19 - 22 2010

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：National Institute of Technology, Toyota College

We have studied the residual strain and stress in semi-polar (1-101)GaN and conventional (0001)GaN grown on Si by means of Raman spectroscopy. By adopting the stress coefficients reported in the references, the residual strain of samples were deduced from the frequency shifts of the phonon modes in Raman spectra. As the results, it was found that the strain tensor of (1-101) GaN/Si was smaller than that of the (0001)GaN/Si in good agreement with the results obtained from the X-ray diffraction measurements.

DOI： 10.20692/toyotakosenkiyo.kj00005889042

Influence of a SiO2 Mask on the Growth of Semi-Polar (11-22) GaN on Patterned Si (311) Substrates

Yang Min, Ahn Hyung Soo, Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. 54 ( 6 ) page： 2363 - 2366 2009.6

Growth and properties of semi-polar GaN on a patterned silicon substrate

Sawaki Nobuhiko, Hikosaka Toshiki, Koide Norikatsu, Tanaka Shigeyasu, Honda Yoshio, Yamaguchi Masahito

JOURNAL OF CRYSTAL GROWTH Vol. 311 ( 10 ) page： 2867 - 2874 2009.5

Maskless selective growth of semi-polar (11(2)over-bar2) GaN on Si (311) substrate by metal organic vapor phase epitaxy

Yang Min, Ahn Hyung Soo, Tanikawa Tomoyuki, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

JOURNAL OF CRYSTAL GROWTH Vol. 311 ( 10 ) page： 2914 - 2918 2009.5

Scattering times in the two-dimensional electron gas of AlxGa1-xN/AlN/GaN heterostructures

Han Xiuxun, Honda Yoshio, Narita Tetsuo, Yamaguchi Masahito, Sawaki Nobuhiko, Tanaka Tooru, Guo Qixin, Nishio Mitsushiro

JOURNAL OF PHYSICS D-APPLIED PHYSICS Vol. 42 ( 4 ) 2009.2

Electron-beam-induced-current investigation of GaN/AlGaN/Si heterostructures using scanning transmission electron microscopy

TANAKA Shigeyasu, AOYAMA Kentaro, ICHIHASHI Mikio, ARAI Shigeo, HONDA Yoshio, SAWAKI Nobuhiko

Journal of electron microscopy Vol. 56 ( 4 ) page： 141 - 144 2007.8

Electron-beam-induced-current investigation of GaN/AlGaN/Si heterostructures using scanning transmission electron microscopy

Tanaka Shigeyasu, Aoyama Kentaro, Ichihashi Mikio, Arai Shigeo, Honda Yoshio, Sawaki Nobuhiko

JOURNAL OF ELECTRON MICROSCOPY Vol. 56 ( 4 ) page： 141 - 144 2007.8

Application of electron holography to the determination of contact potential difference in an AlGaN/AlN/Si heterostructure

TANAKA Shigeyasu, NAITO Akiyuki, HONDA Yoshio, SAWAKI Nobuhiko, ICHIHASHI Mikio

Journal of electron microscopy Vol. 56 ( 2 ) page： 37 - 42 2007.4

Application of electron holography to the determination of contact potential difference in an AIGaN/AIN/Si heterostructure

Tanaka Shigeyasu, Naito Akiyuki, Honda Yoshio, Sawaki Nobuhiko, Ichihashi Mikio

JOURNAL OF ELECTRON MICROSCOPY Vol. 56 ( 2 ) page： 37 - 42 2007.4

Transport properties of the two-dimensional electron gas in AlxGa1-xN/GaN heterostructures

Han Xiuxun, Honda Yoshio, Narita Tetsuo, Yamaguchi Masahito, Sawaki Nobuhiko

JOURNAL OF PHYSICS-CONDENSED MATTER Vol. 19 ( 4 ) 2007.1

Mg doping in (1(1)over-bar01)GaN grown on a 7 degrees off-axis (001)Si substrate by selective MOVPE

Hikosaka Toshiki, Koide Norikatsu, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

JOURNAL OF CRYSTAL GROWTH Vol. 298 page： 207 - 210 2007.1

Carbon incorporation on (1101) facet of AlGaN in metal organic vapor phase epitaxy

Koide Norikatsu, Hikosaka Toshiki, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS Vol. 45 ( 10A ) page： 7655 - 7660 2006.10

The surface diffusion of Ga on an AlGaN/GaN stripe structure in the selective MOVPE

Narita Tetsuo, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 243 ( 7 ) page： 1665 - 1668 2006.6

Series resistance in n-GaN/AIN/n-Si heterojunction structure

Kondo Hiroyuki, Koide Norikatsu, Honda Yoshio, Yamaguchi Masahito, Sawaki Nobuhiko

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS Vol. 45 ( 5A ) page： 4015 - 4017 2006.5

The effect of Si and C doping to the (1-101)GaN grown on a 7-degree-off oriented (001)Si substrate

HIKOSAKA Toshiki, KOIDE Norikatsu, HONDA Yoshio, YAMAGUCHI Masahito, SAWAKI Nobuhiko

Technical report of IEICE. SDM Vol. 105 ( 94 ) page： 69 - 74 2005.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Using a selective MOVPE method, (1-101)GaN was grown on a 7-degree off-axis (001)Si substrate. The top (1-101) surface of the sample was terminated with N, which is contrast to that the (0001) face is terminated with Ga. The doping of Si and C was attempted to control the type of conduction. A nominally undoped GaN/AlN heterostructure showed p-type conduction. The doping of Si changed the type of conduction from p-type to n-type. On the other hand, the hole concentration increased with the C doping level. These results proves that Si acts as a donor and C acts as an acceptor in (1-101)GaN. We might conclude that the p-type conduction is due to the incorporation of C on the top surface of the N face of the GaN.

Selective Growth of GaN/AlGaN Microstructures by Metalorganic Vapor Phase Epitaxy.

[Congenital middle ear cholesteatoma: experience in 48 cases]. Reviewed

Kojima H, Miyazaki H, Tanaka Y, Shiwa M, Honda Y, Moriyama H

Nihon Jibiinkoka Gakkai kaiho Vol. 106 ( 9 ) page： 856 - 65 2003.9

Kato Tomonobu, Honda Yoshio, Kawaguchi Yasutoshi, Yamaguchi Masahito, Sawaki Nobuhiko

Japanese Journal of Applied Physics Vol. 40 ( 3B ) page： 1896 - 1898 2001

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Applied Physics

A GaN/AlGaN double heterostructure was fabricated on the (1101) facets of a GaN triangular structure prepared by selective area growth by metalorganic vapor phase epitaxy. The photoluminescence (PL) and cathode luminescence (CL) spectra were investigated to characterize the structure. It was found that the PL peak wavelength due to the GaN quantum well is dependent on the well thickness. However, the Al composition of the AlGaN layer is dependent on the position on the (1101) facet. The anomalous gradient of the composition is attributed to the difference in the diffusion coefficients of Al and Ga on the surface.

DOI： 10.1143/jjap.40.1896

Selective Area Growth of GaN on Si Substrate Using SiO2 Mask by Metalorganic Vapor Phase Epitaxy.

Kawaguchi Yasutoshi, Honda Yoshio, Matsushima Hidetada, Yamaguchi Masahito, Hiramatsu Kazumasa, Sawaki Nobuhiko

Japanese Journal of Applied Physics Vol. 37 ( 8B ) page： L966 - L969 1998

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Applied Physics

Selective area growth (SAG) of GaN on (111) Si substrate was studied using AlGaN as an intermediate layer. A hexagonal dot with a (0001) plane on the top and of a 5 µm or a submicron size was obtained using a patterned dot structure of silicon dioxide (SiO2) mask. The facet structure revealed that the <11\=20> axis of hexagonal GaN is parallel to the <110> axis of the Si substrate. The cathodoluminescence (CL) spectrum at 133 K exhibited a strong near-band-edge emission band for the submicron dots, which suggests excellent crystallinity. Epitaxial lateral overgrowth (ELO) of GaN on the Si substrate is demonstrated.

DOI： 10.1143/jjap.37.l966

Pulsed-flow growth of polar, semipolar and nonpolar AlGaN

Dinh Duc V, Hu Nan, Honda Yoshio, Amano Hiroshi, Pristovsek Markus

JOURNAL OF MATERIALS CHEMISTRY C Vol. 8 ( 25 ) page： 8668 - 8675 2020.7

Change of high-voltage conduction mechanism in vertical GaN-on-GaN Schottky diodes at elevated temperatures Reviewed

Sandupatla Abhinay, Arulkumaran Subramaniam, Ng Geok Ing, Ranjan Kumud, Deki Manato, Nitta Shugo, Honda Yoshio, Amano Hiroshi

APPLIED PHYSICS EXPRESS Vol. 13 ( 7 ) page： . 2020.7

Effect of Annealing on the Electrical and Optical Properties of MgZnO Films Deposited by Radio Frequency Magnetron Sputtering

Kushimoto Maki, Sakai Tadayoshi, Ueoka Yoshihiro, Tomai Shigekazu, Katsumata Satoshi, Deki Manato, Honda Yoshio, Amano Hiroshi

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE Vol. 217 ( 14 ) 2020.7

Halide vapor phase epitaxy of p-type Mg-doped GaN utilizing MgO Reviewed

Ohnishi Kazuki, Amano Yuki, Fujimoto Naoki, Nitta Shugo, Honda Yoshio, Amano Hiroshi

APPLIED PHYSICS EXPRESS Vol. 13 ( 6 ) page： . 2020.6

Lattice bow in thick, homoepitaxial GaN layers for vertical power devices Reviewed

Liu Qiang, Fujimoto Naoki, Shen Jian, Nitta Shugo, Tanaka Atsushi, Honda Yoshio, Sitar Zlatko, Bockowski Michal, Kumagai Yoshinao, Amano Hiroshi

JOURNAL OF CRYSTAL GROWTH Vol. 539 page： . 2020.6

Demonstration of Observation of Dislocations in GaN by Novel Birefringence Method

Tanaka Atsushi, Inotsume Syo, Harada Shunta, Hanada Kenji, Honda Yoshio, Ujihara Toru, Amano Hiroshi

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 257 ( 4 ) 2020.4

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Herein, a newly developed birefringence microscope is used to observe dislocations in gallium nitride (GaN) substrates. The comparison results of the observation method using this microscope with other observation methods, such as X-ray topography and Raman microscopy, confirms that dislocations in a GaN substrate can be detected with a birefringence microscope. In addition, the observation can be carried out as easily as with an optical microscope. It is also found that under certain observation conditions, the direction of the edge component of dislocations can be determined.

DOI： 10.1002/pssb.201900553

On-wafer fabrication of etched-mirror UV-C laser diodes with the ALD-deposited DBR

Sakai Tadayoshi, Kushimoto Maki, Zhang Ziyi, Sugiyama Naoharu, Schowalter Leo J, Honda Yoshio, Sasaoka Chiaki, Amano Hiroshi

APPLIED PHYSICS LETTERS Vol. 116 ( 12 ) 2020.3

Indium incorporation and optical properties of polar, semipolar and nonpolar InAlN

Dinh Duc V, Hu Nan, Honda Yoshio, Amano Hiroshi, Pristovsek Markus

SEMICONDUCTOR SCIENCE AND TECHNOLOGY Vol. 35 ( 3 ) 2020.3

Optimization of InGaN thickness for high-quantum-efficiency Cs/O-activated InGaN photocathode

Sato Daiki, Honda Anna, Koizumi Atsushi, Nishitani Tomohiro, Honda Yoshio, Amano Hiroshi

MICROELECTRONIC ENGINEERING Vol. 223 2020.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER

The quantum efficiency (QE) of an InGaN photocathode as a function of InGaN layer thickness (240, 100, and 70 nm) was investigated. To activate the sample surface, Cs and O were deposited on the surface in an ultrahigh-vacuum chamber. The QE for different optical power densities was measured by irradiating excitation light from the front and back sides of each sample. The QEs for InGaN layer thickness of 240, 100, and 70 nm with back-side irradiation were 0.9, 9.8, and 7.5%, respectively. For the thicknesses of 70 and 100 nm, the QEs were higher for back-side irradiation than for front-side irradiation, whereas for the thickness of 240 nm, the QE was higher for front-side irradiation. The InGaN layer thickness dependence of the QEs for back- and front-side irradiations was calculated using a continuous equation considering processes such as excitation, diffusion, recombination, and escape of electrons from the surface of the photocathode. The tendency of the experimental results, where QE was maximum at 100-120 nm, corresponded to that of the calculated results.

DOI： 10.1016/j.mee.2020.111229

Analysis of trimethylgallium decomposition by high-resolution mass spectrometry

Ye Zheng, Nitta Shugo, Honda Yoshio, Pristovsek Markus, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 59 ( 2 ) 2020.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

The decomposition of trimethylgallium (Ga(CH3)(3)) was examined under H-2 and N-2 atmospheres using a high-resolution (about 0.002 u) time-of-flight mass spectrometry system, which enabled the separation of N-2 and ethene (C2H4) signals. Under H-2 atmosphere, the main decomposition product was methane (CH4) formed by the hydrogenolysis of Ga(CH3)(3). However, under N-2 atmosphere, the main product is ethane (C2H6) at temperature lower than 660 degrees C. Above 660 degrees C, the C2H6 further decomposes into CH4, acetylene (C2H2) and C2H4, and the main components in the gas phase are C2H2 and C2H4 above 1000 degrees C. Since these are effective carbon dopants, the molar ratio of H-2 to the Ga(CH3)(3) raw material in the carrier gas should be maintained above 300 to inhibit the formation of hydrocarbons in N-2. (C) 2020 The Japan Society of Applied Physics

DOI： 10.35848/1347-4065/ab6fb0

Scalable synthesis of multilayer h-BN on AlN by metalorganic vapor phase epitaxy: nucleation and growth mechanism

Yang Xu, Nitta Shugo, Pristovsek Markus, Liu Yuhuai, Liao Yaqiang, Kushimoto Maki, Honda Yoshio, Amano Hiroshi

2D MATERIALS Vol. 7 ( 1 ) 2020.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

We studied the nucleation and growth of hexagonal BN (h-BN) on AlN template on c-plane sapphire by metalorganic vapor phase epitaxy as functions of growth temperature, deposition time, and triethylboron (TEB) partial pressure. A lateral growth rate of about 25 nm min(-1) for h-BN nuclei was obtained by atomic force microscopy and a nucleation activation energy of 2.1 eV was extracted from the temperature dependence of the nucleation density. A large TEB flow rate strongly enhances the formation of h-BN nuclei. At a reduced TEB flow rate, we observed a significantly decreased nuclei density and a delay in nucleation due to TEB desorption. By fine tuning the growth parameters, single-crystalline multilayer h-BN was successfully formed on AlN surface, as confirmed by x-ray diffraction and transmission electron microscopy (TEM). The epitaxial relationship between h-BN and AlN was [0 0 0 1](h-BN) parallel to [0 0 0 1](AlN) and [1 0 -10](h-BN) parallel to [1 1 -20](AlN) from TEM and electron backscatter diffraction measurements. In addition, TEM showed that the initial h-BN layers are not parallel and tend to form half-domes. On those half-domes (cap-shaped-like) a 2D lateral growth sets on, resulting in a well-oriented 2D multilayer observed in TEM. Thus, the surface topography further develops to form a relatively flat surface without wrinkles and finally a typical hexagon-like wrinkled surface at thicker h-BN layers. Particularly, the small h-BN nuclei have dangling bonds at their periphery that can interact with the substrate, forming actual bonds with AlN. Hence the choice on the substrate is important, despite the basal planes of multilayer h-BN are bonded by a weak van der Waals force.

DOI： 10.1088/2053-1583/ab46e6

Untwinned semipolar (10(1)over-bar3) AlxGa1-xN layers grown on m-plane sapphire

Dinh Duc V, Hu Nan, Amano Hiroshi, Honda Yoshio, Pristovsek Markus

SEMICONDUCTOR SCIENCE AND TECHNOLOGY Vol. 34 ( 12 ) 2019.12

Low Voltage High-Energy α-Particle Detectors by GaN-on-GaN Schottky Diodes with Record-High Charge Collection Efficiency. Reviewed

Sandupatla A, Arulkumaran S, Ranjan K, Ng GI, Murmu PP, Kennedy J, Nitta S, Honda Y, Deki M, Amano H

Sensors (Basel, Switzerland) Vol. 19 ( 23 ) 2019.11

Aluminium incorporation in polar, semi- and non-polar AlGaN layers: a comparative study of x-ray diffraction and optical properties

Duc V Dinh, Hu Nan, Honda Yoshio, Amano Hiroshi, Pristovsek Markus

SCIENTIFIC REPORTS Vol. 9 ( 1 ) page： 15802 2019.11

V-shaped dislocations in a GaN epitaxial layer on GaN substrate

Tanaka Atsushi, Nagamatsu Kentaro, Usami Shigeyoshi, Kushimoto Maki, Deki Manato, Nitta Shugo, Honda Yoshio, Bockowski Michal, Amano Hiroshi

AIP ADVANCES Vol. 9 ( 9 ) 2019.9

Language：English Publishing type：Research paper (scientific journal)

In this study, V-shaped dislocations in a GaN epitaxial layer on a free-standing GaN substrate were observed. Our investigation further revealed that the V-shaped dislocations were newly generated at the interface in the epilayer rather than propagated from the GaN substrate. V-shaped dislocations consist of two straight parts. The straight parts of the V-shaped dislocations were separated from each other in the m-direction and tilted toward the step-flow direction of the GaN epitaxial layer. The V-shaped dislocations are continuous single dislocations having a Burgers vector component of 1a and an intrinsic stacking fault between their straight parts.

DOI： 10.1063/1.5114866

Origin of acceptor diffusion into silicon substrate during GaN growth by metal organic chemical vapor deposition

Matsumoto Koji, Ono Toshiaki, Honda Yoshio, Torigoe Kazuhisa, Kushimoto Maki, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 ( 7 ) 2019.7

Ammonia decomposition and reaction by high-resolution mass spectrometry for group III - Nitride epitaxial growth

Ye Zheng, Nitta Shugo, Nagamatsu Kentaro, Fujimoto Naoki, Kushimoto Maki, Deki Manato, Tanaka Atsushi, Honda Yoshio, Pristovsek Markus, Amano Hiroshi

JOURNAL OF CRYSTAL GROWTH Vol. 516 page： 63 - 66 2019.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The decomposition of ammonia (NH3) in nitrogen (N-2) ambient was studied under non-equilibrium conditions similar to those in a metal organic vapor phase epitaxy (MOVPE) reactor during the epitaxial growth of group-III nitrides. The gas phase was sampled at different positions and analyzed using a time-of-flight mass spectrometry system with a high resolution (better than 0.002 u). Our results expand earlier findings. Even at the high temperature of 1200 degrees C, only 26% of NH3 decomposed in a clean metal-free reactor, whereas a higher ratio of NH3 decomposition was realized in the presence of stainless steel. The activation energy in the clean reactor was calculated to be 0.965 +/- 0.004 eV. These results demonstrate the capability of our setup and shed new light on the elucidation of the vapor phase growth mechanism of group III-nitrides by MOVPE.

DOI： 10.1016/j.jcrysgro.2019.03.025

Computational fluid dynamics simulation study of the gas flow balance in a vertical HVPE reactor with a showerhead for low cost bulk GaN crystal growth

Liu Qiang, Fujimoto Naoki, Nitta Shugo, Honda Yoshio, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 2019.6

Frontiers of Nitride Semiconductor Research FOREWORD

Chichibu Shigefusa F, Kumagai Yoshinao, Kojima Kazunobu, Deura Momoko, Akiyama Toru, Arita Munetaka, Fujioka Hiroshi, Fujiwara Yasufumi, Hara Naoki, Hashizume Tamotsu, Hirayama Hideki, Holmes Mark, Honda Yoshio, Imura Masataka, Ishii Ryota, Ishitani Yoshihiro, Iwaya Motoaki, Kamiyama Satoshi, Kangawa Yoshihiro, Katayama Ryuji, Kawakami Yoichi, Kawamura Takahiro, Kobayashi Atsushi, Kuzuhara Masaaki, Matsumoto Koh, Mori Yusuke, Mukai Takashi, Murakami Hisashi, Murotani Hideaki, Nakazawa Satoshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 2019.6

Controlling the orientations of directional sputtered non- and semi-polar GaN/AlN layers

Nan Hu, Dinh Duc V, Pristovsek Markus, Honda Yoshio, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 58 2019.6

Comparison of AlxGa1-xN multiple quantum wells designed for 265 and 285nm deep-ultraviolet LEDs grown on AlN templates having macrosteps

Nagasawa Yosuke, Kojima Kazunobu, Hirano Akira, Ipponmatsu Masamichi, Honda Yoshio, Amano Hiroshi, Akasaki Isamu, Chichibu Shigefusa F

APPLIED PHYSICS EXPRESS Vol. 12 ( 6 ) 2019.6

Morphological study of InGaN on GaN substrate by supersaturation (vol 508, pg 58, 2019)

Liu Zhibin, Nitta Shugo, Robin Yoann, Kushimoto Maki, Deki Manato, Honda Yoshio, Pristovsek Markus, Sitar Zlatko, Amano Hiroshi

JOURNAL OF CRYSTAL GROWTH Vol. 514 page： 13 - 13 2019.5

Effect of substrate misorientation on the concentration of impurities and surface morphology of an epitaxial GaN layer on N-polar GaN substrate by MOVPE

Nagamatsu Kentaro, Ando Yuto, Kono Tsukasa, Cheong Heajeong, Nitta Shugo, Honda Yoshio, Pristovsek Markus, Amano Hiroshi

JOURNAL OF CRYSTAL GROWTH Vol. 512 page： 78 - 83 2019.4

Language：English Publishing type：Research paper (scientific journal)

This study examines the effect of (0 0 0 −1) GaN substrate misorientation on the residual impurities and surface morphology of N-polar GaN grown by metalorganic vapor-phase epitaxy. Carbon, silicon, and oxygen concentrations decreased with increasing GaN substrate misorientation angle, with the lowest impurity concentration achieved for a misorientation angle of 2° toward the m-axis, with 6 × 10 15 cm −3 carbon, 6 × 10 15 cm −3 silicon, and 4 × 10 17 cm −3 oxygen atoms. The oxygen concentration was measured at a depth of 0.5 μm below the wafer surface, and the oxygen concentration decreased with increasing thickness. The incorporation of carbon and oxygen revealed a strong dependence on the misorientation angle. The step distance height of the steps parallel to the [1 1 −2 0] direction (or perpendicular to the [1 −1 0 0] m-direction) was confirmed to be a double-height layer step. This phenomenon indicated that m-direction steps are stable for N-polar growth in GaN. In cases of large misorientation toward the m-axis in of the GaN substrate it was difficult to control the misorientation perpendicular to the nominal direction leading to a-axis direction by wafer bowing at wafer manufacturing. Therefore, step-bunching was generated for each symmetric m-axis due to an increase in the compound's off-angle, thus causing the surface roughness to become large.

DOI： 10.1016/j.jcrysgro.2019.02.013

Transfer-free fabrication of a graphene transparent electrode on a GaN-based light-emitting diode using the direct precipitation method Reviewed

Yamada Jumpei, Usami Shigeyoshi, Ueda Yuki, Honda Yoshio, Amano Hiroshi, Maruyama Takahiro, Naritsuka Shigeya

Jpn. J. Appl. Phys. Vol. 58 ( 4 ) 2019.3

Effect of gas phase temperature on InGaN grown by metalorganic vapor phase epitaxy

Zhibin Liu, Shugo Nitta, Shigeyoshi Usami, Yoann Robin, Maki Kushimoto, Manato Deki, Yoshio Honda, Markus Pristovsek, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 509 page： 50 - 53 2019.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Wafer trays with different gaps (the distance between the top of the pocket and the bottom of the wafer) were used to grow InGaN/GaN multiple quantum wells (MQWs) in a horizontal metalorganic vapor phase epitaxy (MOVPE) reactor. The numerical reactor simulation revealed that at the similar surface temperature the gas phase temperature around the wafer increases due to an increased wafer tray temperature. This increased gas phase temperature is expected to increase the effective V/III ratio by enhanced NH3 decomposition. Photoluminescence (PL) intensities of long-wavelength MQWs increased at the same indium content by the enhanced gas phase temperature, while the emission became narrow. This is related to a smoother topography at higher gas phase temperatures.

DOI： 10.1016/j.jcrysgro.2018.12.007

Fully Ion Implanted Normally-Off GaN DMOSFETs with ALD-Al2O3 Gate Dielectrics

Yoshino Michitaka, Ando Yuto, Deki Manato, Toyabe Toru, Kuriyama Kazuo, Honda Yoshio, Nishimura Tomoaki, Amano Hiroshi, Kachi Tetsu, Nakamura Tohru

MATERIALS Vol. 12 ( 5 ) 2019.3

Morphological study of InGaN on GaN substrate by supersaturation

Liu Zhibin, Nitta Shugo, Robin Yoann, Kushimoto Maki, Deki Manato, Honda Yoshio, Pristovsek Markus, Amano Hiroshi

JOURNAL OF CRYSTAL GROWTH Vol. 508 page： 58 - 65 2019.2

How to obtain metal-polar untwinned high-quality (10-13) GaN on m-plane sapphire

Hu Nan, Dinh Duc V, Pristovsek Markus, Honda Yoshio, Amano Hiroshi

JOURNAL OF CRYSTAL GROWTH Vol. 507 page： 205 - 208 2019.2

Vertical GaN p-n diode with deeply etched mesa and the capability of avalanche breakdown

Hayata Fukushima, Shigeyoshi Usami, Masaya Ogura, Yuto Ando, Atsushi Tanaka, Manato Deki, Maki Kushimoto, Shugo Nitta, Yoshio Honda, Hiroshi Amano

APPLIED PHYSICS EXPRESS Vol. 12 ( 2 ) 2019.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

A simple structure with high breakdown voltage and a low leakage current of a vertical GaN p-n diode on a GaN free-standing substrate is demonstrated. We describe a vertical p-n diode with a simple edge termination that has a drift layer etched deeply and vertically. A device simulation revealed that the electric field was more relaxed at the device edge and applied uniformly in the entire device with increasing etching depth. We fabricated the simulated structure and succeeded in reducing the leakage current and improving the breakdown voltage. With this structure, a stable avalanche breakdown can be observed. (C) 2019 The Japan Society of Applied Physics

DOI： 10.7567/1882-0786/aafdb9

Observation of Dopant Concentration in GaN Semiconductor by High Sensitivity Electron Holography

Carrier localization structure combined with current micropaths in AlGaN quantum wells grown on an AIN template with macrosteps

Kojima K, Nagasawa Y, Hirano A, Ippommatsu M, Honda Y, Amano H, Akasaki I, Chichibu S. F

APPLIED PHYSICS LETTERS Vol. 114 ( 1 ) 2019.1

Nakano Kiyotaka, Honda Yoshio, Amano Hiroshi, Matsumoto Miko, Anada Satoshi, Yamamoto Kazuo, Ishikawa Yukari, Hirayama Tsukasa, Ando Yuto, Ogura Masaya, Tanaka Atsushi

Materia Japan Vol. 58 ( 2 ) page： 103-103 - 103 2019

Analysis of negative electron affinity InGaN photocathode by temperature-programed desorption method

Kashima Masahiro, Sato Daiki, Koizumi Atsushi, Nishitani Tomohiro, Honda Yoshio, Amano Hiroshi, Iijima Hokuto, Meguro Takashi

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B Vol. 36 ( 6 ) 2018.11

Language：English Publishing type：Research paper (scientific journal) Publisher：A V S AMER INST PHYSICS

A III-V semiconductor with a few monolayers of alkali metals (e.g., Cs) forms a negative electron affinity (NEA) surface, for which the vacuum level lies below the conduction band minimum of the base semiconductor. The photocathodes that form an NEA surface (NEA photocathodes) have various advantages, such as low emittance, a large current, high spin polarization, and ultrashort pulsed operation. The NEA-InGaN photocathode, which is sensitive to blue light, has been studied as a material for the next-generation robust photocathode. However, the proper conditions for forming NEA surfaces remain unknown. The authors consider whether the suitable process for NEA surfaces can be understood by investigating the relationship between the electron emission and the adsorption state of alkali metals. In this study, the relationship between the electron emission and the adsorption state of Cs on the p-type InGaN (0001) was analyzed by the temperature programed desorption (TPD) method using a quadrupole mass spectrometer. From the results of the TPD measurements, it was shown that there were several adsorption states of Cs on InGaN. The quantum efficiency (QE), which indicates the ratio of emitted electrons to incident photons, increased while Cs desorption occurred. The authors divided the formation process of an NEA surface into several sections to investigate the adsorption states of Cs related to the electron emission and to discuss the reasons why the QE increased despite the desorbed Cs. From the results of the NEA activation in each section, it was shown that there were sections where the QE increased by reacting with O-2 after Cs supply stopped. There is a possibility that several layers reacting with O-2 and those not reacting with O-2 are formed by performing NEA activation until the QE saturates. From the results of the TPD measurements in each section, it was suggested that there was a Cs peak at above 700 degrees C when the TPD method was carried out immediately after confirming the electron emission. Therefore, the adsorption state of Cs that formed a peak at above 700 degrees C had a close relation to the electron emission. It is considered that the increase of the QE in the TPD was affected by adsorbed Cs compounds that reacted with O-2. Although the mechanism is not understood, it is known that the QE was increased by the reaction of Cs adsorbed compounds and O-2 in previous studies. It was suspected that layers that reacted with O-2 appeared from TPD and then the QE increased by reacting with O-2. Published by the AVS.

DOI： 10.1116/1.5048061

High-temperature thermal annealing of nonpolar (10(1)over-bar0) AlN layers sputtered on (1 0(1)over-bar0) sapphire

Comparing high-purity c- and m-plane GaN layers for Schottky barrier diodes grown homoepitaxially by metalorganic vapor phase epitaxy Reviewed

Vol. 57 ( 10 ) 2018.10

Dinh Duc V, Hu Nan, Honda Yoshio, Amano Hiroshi, Pristovsek Markus

JOURNAL OF CRYSTAL GROWTH Vol. 498 page： 377 - 380 2018.9

Detailed study of effects of duration of pre-AIN-growth trimethylaluminum step on morphologies of GaN layers grown on silicon substrate by metal organic chemical vapor deposition Reviewed

Vol. 57 ( 9 ) 2018.9

Reduction of Residual Impurities in Homoepitaxial m-Plane (10(1)over-bar0) GaN by Using N-2 Carrier Gas in Metalorganic Vapor Phase Epitaxy

Barry Ousmane I, Lekhal Kaddour, Bae Si-Young, Lee Ho-Jun, Pristovsek Markus, Honda Yoshio, Amano Hiroshi

PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS Vol. 12 ( 8 ) 2018.8

Improvement of breakdown voltage of vertical GaN p-n junction diode with Ga2O3 passivated by sputtering

Ueoka Yoshihiro, Deki Meneto, Honda Yoshio, Amano Hiroshi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 57 ( 7 ) 2018.7

Study on the Main-Chain Structure of Amorphous Fluorine Resins for Encapsulating AlGaN-Based DUV-LEDs

Kiho Yamada, Yosuke Nagasawa, Shoko Nagai, Akira Hirano, Masamichi Ippommatsu, Ko Aosaki, Yoshio Honda, Hiroshi Amano, Isamu Akasaki

Physica Status Solidi (A) Applications and Materials Science Vol. 215 ( 10 ) 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley-VCH Verlag

The main chain structure of optically isotropic amorphous fluorine resin for encapsulating AlGaN-based deep-ultraviolet LEDs (λ &lt
300 nm) is studied. One type of amorphous fluorine resin has a five-membered ring with a single oxygen atom and the other has that one with two oxygen atoms. Reliability testing is performed using AlGaN-based LEDs of 262 and 289 nm. For the resin with two oxygen atoms in the ring, visible damage to the electrode and significantly increased leakage current are considered to been caused by the photolysis of the ring induced by irradiation with deep-ultraviolet light. In contrast, electrode damage and increased leakage are not observed in the case of the resin with the single-oxygen ring.

DOI： 10.1002/pssa.201700525

m-Plane GaN Schottky Barrier Diodes Fabricated With MOVPE Layer on Several Off-Angle m-Plane GaN Substrates

Atsushi Tanaka, Yuto Ando, Kentaro Nagamatsu, Manato Deki, Heajeong Cheong, Barry Ousmane, Maki Kushimoto, Shugo Nitta, Yoshio Honda, Hiroshi Amano

Physica Status Solidi (A) Applications and Materials Science Vol. 215 ( 9 ) 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley-VCH Verlag

In this study, GaN m-plane Schottky barrier diodes are fabricated by metalorganic vapor-phase epitaxy (MOVPE) on several off-angle gallium nitride (GaN) substrates, and the off-cut angle dependence of impurity incorporation is investigated. We show that the MOVPE layer on the substrate inclined 5° toward the [000–1] direction has extremely low impurity incorporation. These results provide important suggestions for the fabrication of m-plane power devices.

DOI： 10.1002/pssa.201700645

Reduction of Dislocations in GaN on Silicon Substrate Using In Situ Etching

Interface amorphization in hexagonal boron nitride films on sapphire substrate grown by metalorganic vapor phase epitaxy Reviewed

Vol. 11 ( 5 ) 2018.5

Koji Matsumoto, Toshiaki Ono, Yoshio Honda, Tetsuya Yamamoto, Shigeyoshi Usami, Maki Kushimoto, Satoshi Murakami, Hiroshi Amano

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 255 ( 5 ) 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

A gallium nitride (GaN) epitaxial layer with a low density of threading dislocations is successfully grown on a silicon substrate by using in situ gas etching. Silicon nitride (SiNx) film is used as a mask, and ammonia is intermittently supplied in hydrogen ambient during the etching. After etching, high-density deep pits appeared on the surface of a GaN template layer and corresponded to the threading dislocations in the layer. In this novel method, before growing an additional GaN layer on the template GaN layer, a second SiNx layer is deposited after the etching process, and this layer prevents GaN nuclei from growing on the upper side-walls of the pits. By using this method, the density of threading dislocations of the GaN surface is reduced to 6.7x10(7)cm(-2). This method is cost effective, completing all the necessary processes in one growth run without taking samples out from a metalorganic chemical vapor deposition (MOCVD) reactor.

DOI： 10.1002/pssb.201700387

Correlation between dislocations and leakage current of p-n diodes on a free-standing GaN substrate

Shigeyoshi Usami, Yuto Ando, Atsushi Tanaka, Kentaro Nagamatsu, Manato Deki, Maki Kushimoto, Shugo Nitta, Yoshio Honda, Hiroshi Amano, Yoshihiro Sugawara, Yong-Zhao Yao, Yukari Ishikawa

APPLIED PHYSICS LETTERS Vol. 112 ( 18 ) 2018.4

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

Dislocations that cause a reverse leakage current in vertical p-n diodes on a GaN free-standing substrate were investigated. Under a high reverse bias, dot-like leakage spots were observed using an emission microscope. Subsequent cathodoluminescence (CL) observations revealed that the leakage spots coincided with part of the CL dark spots, indicating that some types of dislocation cause reverse leakage. When etch pits were formed on the dislocations by KOH etching, three sizes of etch pits were obtained (large, medium, and small). Among these etch pits, only the medium pits coincided with leakage spots. Additionally, transmission electron microscopy observations revealed that pure screw dislocations are present under the leakage spots. The results revealed that lc pure screw dislocations are related to the reverse leakage in vertical p-n diodes. Published by AIP Publishing.

DOI： 10.1063/1.5024704

Growth of hexagonal boron nitride on sapphire substrate by pulsed-mode metalorganic vapor phase epitaxy International journal

Xu Yang, Shugo Nitta, Kentaro Nagamatsu, Si-Young Bae, Ho-Jun Lee, Yuhuai Liu, Markus Pristovsek, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 482 page： 1 - 8 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Hexagonal boron nitride (h-BN) was directly grown on sapphire substrate using alternating ammonia (NH3) and triethylboron (TEB) supply (pulsed mode) in metalorganic vapor phase epitaxy. The best condition is when just enough NH3 is supplied to fully convert the TEB within one cycle. Excess NH3 caused islands on h-BN film surface while a lack of NH3 does not form h-BN at all. The epitaxial relationship between grown h-BN layer and c-plane sapphire was confirmed to be [0001](h-BN)||[0001](sapphire) and [10-10](h-BN)||[11-20](sapphire). It is known that, compared to AlN, BN requires higher V/III ratios for good crystallinity, which due to severe gas-phase reactions is difficult to achieve using continuous supply. Thus using pulsed mode the FWHM of the symmetric (0002) diffraction was almost halved and the growth rate was several times faster. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jcrysgro.2017.10.036

Theoretical Study of the Electronic Structure of Threading Edge Dislocations in GaN

Nakano Takashi, Araidai Masaaki, Shiraishi Kenji, Tanaka Atsushi, Honda Yoshio, Amano Hiroshi

GALLIUM NITRIDE AND SILICON CARBIDE POWER TECHNOLOGIES 8 Vol. 86 ( 12 ) page： 41 - 49 2018

Electrical and Thermal Analysis of Vertical GaN-on-GaN PN Diodes

Yates Luke, Pavlidis Georges, Graham Samuel, Usami Shigeyoshi, Nagamatsu Kentaro, Honda Yoshio, Amano Hiroshi

PROCEEDINGS OF THE 17TH IEEE INTERSOCIETY CONFERENCE ON THERMAL AND THERMOMECHANICAL PHENOMENA IN ELECTRONIC SYSTEMS (ITHERM 2018) page： 831-837 2018

Charge-to-time converting leading-edge discriminator for plastic-scintillator signals International journal

T. Ishikawa, Y. Takeda, Y. Honda, Y. Inoue, H. Kanda, S. Kido, Y. Matsumura, M. Miyabe, I. Nagasawa, H. Shimizu, T. Takeda, A. O. Tokiyasu, Y. Tsuchikawa, H. Yamazaki

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 875 page： 193 - 200 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We have developed a charge-to-time converting (QTC) leading-edge discriminator for plastic-scintillator signals, which is packaged in a NIM-standard double-width module. The pulse width of the discriminator output is approximately proportional to the charge integration of input signals up to 40-50 pC. The non-linearity is 20%, 10%, 4%, and 2% at maximum for the input charges below 7 pC, for 7-10 pC, for 10-20 pC, and above 20 pC, respectively, for the minimum input charges larger than 2 pC. The discriminator could be suitable in the measurement of the timing and charge of plastic-scintillator signals together with a multi-hit time-to-digital converter (TDC) module. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nima.2017.09.040

Initial leakage current paths in the vertical-type GaN-on-GaN Schottky barrier diodes International journal

Liwen Sang, Bing Ren, Masatomo Sumiya, Meiyong Liao, Yasuo Koide, Atsushi Tanaka, Yujin Cho, Yoshitomo Harada, Toshihide Nabatame, Takashi Sekiguchi, Shigeyoshi Usami, Yoshio Honda, Hiroshi Amano

APPLIED PHYSICS LETTERS Vol. 111 ( 12 ) 2017.9

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

Electrical characteristics of leakage current paths in vertical-type n-GaN Schottky barrier diodes (SBDs) on free-standing GaN substrates are investigated by using photon emission microscopy (PEM). The PEM mapping shows that the initial failure of the SBD devices at low voltages is due to the leakage current paths from polygonal pits in the GaN epilayers. It is observed that these polygonal pits originate from carbon impurity accumulation to the dislocations with a screw-type component by microstructure analysis. For the SBD without polygonal pits, no initial failure is observed and the first leakage appeals at the edge of electrodes as a result of electric field concentration. The mechanism of leakage at pits is explained in terms of trap assisted tunneling through fitting current-voltage characteristics.

DOI： 10.1063/1.4994627

Facet dependence of leakage current and carrier concentration in m-plane GaN Schottky barrier diode fabricated with MOVPE International journal

Atsushi Tanaka, Ousmane Barry, Kentaro Nagamatsu, Junya Matsushita, Manato Deki, Yuto Ando, Maki Kushimoto, Shugo Nitta, Yoshio Honda, Hiroshi Amano

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE Vol. 214 ( 8 ) 2017.8

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

In this study, GaN m-plane Schottky barrier diodes fabricated with a metalorganic vapor-phase epitaxy on a GaN substrate were investigated using emission microscope, photoluminescence, and cathodoluminescence. In addition, facet dependence of leakage current under reverse-biased condition was observed. We showed that the leakage-current distribution was caused by the facet dependence of the carrier concentration and oxygen concentration. These results can provide important suggestions for the fabrication of m-plane devices. (a) four-faceted hillocks on m-plane GaN MOVPE sample, facet dependence of (b) leakage current and (c) PL peak intensity of the m-plane GaN Schottky barrier diode.

DOI： 10.1002/pssa.201600829

Effect of dislocations on the growth of p-type GaN and on the characteristics of p-n diodes International journal

Shigeyoshi Usami, Ryosuke Miyagoshi, Atsushi Tanaka, Kentaro Nagamatsu, Maki Kushimoto, Manato Deki, Shugo Nitta, Yoshio Honda, Hiroshi Amano

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE Vol. 214 ( 8 ) 2017.8

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

We investigate the influence of crystal defects on p-type GaN grown by metalorganic vapor phase epitaxy. Sets of p-type GaN films were grown on sapphire substrates and on free-standing GaN (F-GaN) substrates simultaneously using various Et-Cp2Mg flow rates. Although there is a difference of two orders of magnitude between the threading dislocation densities of p-type GaN grown on sapphire and F-GaN substrates, there is no significant difference in hole concentration. However, there are problems with the surface morphology of p-type GaN grown on sapphire. The deterioration of the surface was caused by the difference in nanopipe density. The electrical properties of a p-n junction diode formed on sapphire with a high density of nanopipes were observed using emission microscopy under both forward- and reverse-bias conditions. Our results demonstrate that the nanopipes are electrically inactive, and that other types of threading dislocation have more influence on the current-voltage characteristics.

DOI： 10.1002/pssa.201600837

Decomposition of trimethylgallium and adduct formation in a metalorganic vapor phase epitaxy reactor analyzed by high-resolution gas monitoring system International journal

Kentaro Nagamatsu, Shugo Nitta, Zheng Ye, Hirofumi Nagao, Shinichi Miki, Yoshio Honda, Hiroshi Amano

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 254 ( 8 ) 2017.8

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

In this study, by using time-of-flight (TOF) high-resolution and high-sensitivity mass spectrometry measurements, the decomposition of trimethylgallium into dimethylgallium and monomethylgallium along with its adduct formation with NHx in a commercially available horizontal metalorganic vapor-phase epitaxy (MOVPE) reactor with a resistive heater was investigated and observed in more detail than previously reported. The results confirmed the use of the TOF monitoring system in analyzing the elementary reaction process in actual MOVPE systems. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

DOI： 10.1002/pssb.201600737

Absolute technique for measuring internal electric fields in InGaN/GaN light-emitting diodes by electroreflectance applicable to all crystal orientations International journal

Tomoyuki Tanikawa, Kanako Shojiki, Ryuji Katayama, Shigeyuki Kuboya, Takashi Matsuoka, Yoshio Honda, Hiroshi Amano

APPLIED PHYSICS EXPRESS Vol. 10 ( 8 ) 2017.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

The internal electric fields in III-polar (0001), N-polar (0001), and semipolar (1011) InGaN/GaN light-emitting diodes were investigated by electroreflectance (ER) spectroscopy. The ER spectra reflected the difference in the direction and strength of internal electric fields. Phase analyses of the ER signal revealed that only III-polar InGaN wells have the opposite direction of the internal electric field at zero bias voltage; this finding is in good agreement with the results of numerical analyses. Quantitative analyses of internal electric fields were conducted by the linewidth analyses of ER spectra. Our experimental results indicate that the absolute value of internal electric fields can be measured from ER spectra. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/APEX.10.082101

Selective-area growth of doped GaN nanorods by pulsed-mode MOCVD: Effect of Si and Mg dopants

Si-Young Bae, Kaddour Lekhal, Ho-Jun Lee, Jung-Wook Min, Dong-Seon Lee, Yoshio Honda, Hiroshi Amano

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 254 ( 8 ) 2017.8

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Injecting current with a uniform carrier concentration is important for applications with three-dimensional architectures such as vertical power devices or displays. In III-nitride nanostructures, dopants not only incorporate differently depending on the surface orientation but can also seriously affect the kinetic equilibrium shapes of the nanorods. Herein, we report selective-area growth of doped GaN nanorods grown by pulsed-mode metalorganic chemical vapor deposition. Two dopants, Si and Mg, were employed as donor and acceptor atoms, respectively, for a mono-doping approach. Furthermore, a mixed flow of Si and Mg was supplied for a co-doping approach. We compared the morphological effects and growth rates of each doped GaN nanorod array. Then, we proposed appropriate growth mechanisms for the doped GaN nanorods on the basis of our structural characterizations. These results might extend the morphological functionality of GaN nanorods by including doping and may also provide an appropriate foundation for the design of nanostructure-based electronic or photonic devices. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

DOI： 10.1002/pssb.201600722

A-plane GaN growth on (11-20) 4H-SiC substrate with an ultrathin interlayer International journal

Zheng Sun, Peifeng Song, Shugo Nitta, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 468 page： 866 - 869 2017.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

A-plane GaN was attempted to be grown on (11-20) 4H-SiC bulk substrate without using a traditional thick buffer layer. By inducing TMAl treatment before the GaN growth step and using both a low pressure and V/III ratio, the interlayer thickness of the a-plane GaN/SiC was reduced to 1.7 +/- 0.5 nm. The ultrathin interlayer was observed to be either AlN or AlGaN with a low Ga composition. This study is aimed to contribute to the understanding of GaN growth on the sidewalls of c-plane trench structure SiC. The ultrathin growth technique is also hoped to be applied to the fabrication of GaN-based vertical structure nonpolar optical or electrical devices.

DOI： 10.1016/j.jcrysgro.2017.01.031

Effect of V/III ratio on the surface morphology and electrical properties of m-plane (10(1)over-bar0) GaN homoepitaxial layers International journal

Ousmane I. Barry, Atsushi Tanaka, Kentaro Nagamatsu, Si-Young Bae, Kaddour Lekhal, Junya Matsushita, Manato Deki, Shugo Nitta, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 468 page： 552 - 556 2017.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We have investigated the effect of V/III ratio on the surface morphology, impurity concentration and electrical properties of m-plane (10 (1) over bar0) Gallium Nitride (GaN) homoepitaxial layers. Four-sided pyramidal hillocks are observed on the nominally on-axis m-plane GaN films. Hillocks sizes relatively increase by increasing the V/III ratio. All facets of pyramidal hillocks exhibit well-defined step-terrace features. Secondary ion mass spectrometry depth profiles reveal that carbon impurities decrease by increasing the V/III ratio while the lowest oxygen content is found at an optimized V/III ratio of 900. Vertical Schottky barrier diodes fabricated on the m-GaN samples were characterized. Low leakage current densities of the order of 10(-10) A/cm(2) at -5 V are obtained at the optimum V/III ratio. Oxygen impurities and screw-component dislocations around hillocks are found to have more detrimental impact on the leakage current mechanism.

DOI： 10.1016/j.jcrysgro.2016.12.012

Orientation-controlled epitaxial lateral overgrowth of semipolar GaN on Si(001) with a directionally sputtered AlN buffer layer International journal

Ho-Jun Lee, Si-Young Bae, Kaddour Lekhal, Akira Tamura, Takafumi Suzuki, Maki Kushimoto, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 468 page： 547 - 551 2017.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We successfully grew semipolar (10 (1) over bar3) and (10 (1) over bar5) GaN films on Si(001) substrates employing metal-organic chemical vapor deposition (MOCVD) by inserting a directionally sputtered AlN (DS-AlN) buffer layer. To improve the crystal quality of the orientation-controlled semipolar (10 (1) over bar3) and (10 (1) over bar5) GaN films, a two-step epitaxial lateral overgrowth (ELO) process was performed with a striped mask. According to low-temperature cathodoluminescence (LT-CL) characterization, the ELO results in a coalesced morphology and a low defect density of < 2.72x10(8) cm(-2) for both semipolar (10<(1)over bar>3) and (10 (1) over bar5) GaN films. For comparing the properties of planar and ELO semipolar GaN, a rocking curve of x-ray diffraction (XRD) and low-temperature photoluminescence (LT-PL) spectra was measured. The crystal orientation of semipolar GaN films was confirmed using electron backscatter diffraction (EBSD).

DOI： 10.1016/j.jcrysgro.2016.11.116

Annealing effect on threading dislocations in a GaN grown on Si substrate International journal

H. Iwata, H. Kobayashi, T. Kamiya, R. Kamei, H. Saka, N. Sawaki, M. Irie, Y. Honda, H. Amano

JOURNAL OF CRYSTAL GROWTH Vol. 468 page： 835 - 838 2017.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Effect of rapid thermal annealing (RTA) on crystal defects in a GaN layer grown on a (111) Si substrate was investigated by photoluminescence (PL) and transmission electron microscopy (TEM) analyses. The PL spectra suggested that the density of gallium vacancy is not changed by the heat treatment up to 700 degrees C. In the TEM specimen, we had dislocation half loops generated by off-axis propagation of the threading dislocation. We found that the half-loop of c-type dislocation shrinks/moves by a repetitive RTA at 600-700 degrees C. In contrast, we could find no remarkable changes in the a-type or a+c-type dislocations.

DOI： 10.1016/j.jcrysgro.2017.01.001

Selective-area growth of vertically oriented GaN nanostructures with a hafnium pre-orienting layer International journal

S. -Y. Bae, K. Lekhal, H. -J. Lee, T. Mitsunari, J. -W. Min, D. -S. Lee, M. Kushimoto, Y. Honda, H. Amano

JOURNAL OF CRYSTAL GROWTH Vol. 468 page： 110 - 113 2017.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Severe melt-back etching has forced the epitaxy of GaN on Si to use an AlN buffer layer for growing high-quality two-dimensional layers, despite its high resistivity. Herein, we report a metal-based pre-orienting layer (POL) for growing GaN nanostructures (NSs) to replace the traditional AlN buffer layer. Two metals, titanium (Ti) and hafnium (Hf), were evaluated as POLs. We succeeded in fabricating arrays of GaN NSs with highly preferred orientation using selective-area growth. The crystallographic phase of the POLs critically affected the evolved orientation of the crystals. Photoluminescence measurements revealed that GaN NSs with Hf-based POLs were of reasonably high quality. We believe that this result will facilitate broader III-V semiconductor applications using alternative substrates moving beyond conventional Si-based optoelectronics.

DOI： 10.1016/j.jcrysgro.2016.10.032

Uneven AlGaN multiple quantum well for deep-ultraviolet LEDs grown on macrosteps and impact on electroluminescence spectral output Reviewed

Vol. 56 ( 6 ) 2017.6

III-nitride core-shell nanorod array on quartz substrates Reviewed

Vol. 7 2017.3

AlN and AlGaN layers grown on Si(111) substrate by mixed-source hydride vapor phase epitaxy method International journal

Hunsoo Jeon, Injun Jeon, Gang Seok Lee, Sung Geun Bae, Hyung Soo Ahn, Min Yang, Sam Nyung Yi, Young Moon Yu, Yoshio Honda, Nobuhiko Sawaki, Suck-Whan Kim

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 56 ( 1 ) 2017.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

High Al-composition AlGaN and AlN epilayers were grown directly on Si(111) substrate by a hydride vapor phase epitaxy (HVPE) method with a melted mixed source in a graphite boat set in a source zone with high temperatures of T = 700 and 800 degrees C, respectively. The presence of the Ga material in the mixed source of Ga and Al promoted the growth of AlN and AlGaN epilayers in the growth zone. When the temperature in the source zone was 800 degrees C, the crystalline quality of the AlN and AlGaN epilayers increased as the ratio of Ga to Al increased, and the optimum mix ratio of Ga to Al for the growth of AlN epilayers was approximately 0.35-0.42, obtained from a numerical fitting analysis of the X-ray diffraction (XRD) data for these epilayers. It appears that they can be grown directly by our melted-mixed-source HVPE method in a high-temperature source zone. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.56.01AD07

Mechanism of light emission and manufacturing process of vertical-type light-emitting diode grown by hydride vapor phase epitaxy International journal

Gang Seok Lee, Hunsoo Jeon, Hyung Soo Ahn, Min Yang, Sam Nyung Yi, Young Moon Yu, Sang Chil Lee, Yoshio Honda, Nobuhiko Sawaki, Suck-Whan Kim

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 56 ( 1 ) 2017.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

We developed a vertical-type light-emitting diode (LED) in which the substrate is removed using a hydride vapor phase epitaxy (HVPE) apparatus consisting of a multi-graphite boat filled with a mixed source and a high-temperature (T approximate to 900 degrees C) RF heating coil outside the source zone. The new chip-growth process with a significant reduction in the number of production steps is completed in only four steps, namely, photolithography, epitaxial layer growth, sorting, and metallization. We analyze the emission mechanism of these lights from measurement results to validate the characteristics of the light emitted from these vertical-type blue LEDs and white LEDs (WLEDs) without substrates, and propose that this mixed-source HVPE method may be a promising production technique for LEDs. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.56.01AD03

Development of Sustainable Smart Society based on Transformative Electronics Reviewed

page： . 2017

Development of Sustainable Smart Society based on Transformative Electronics

Ogura M, Ando Y, Usami S, Nagamatsu K, Kushimoto M, Deki M, Tanaka A, Nitta S, Honda Y, Pristovsek M, Kawai H, Yagi S, Amano H

2017 IEEE INTERNATIONAL ELECTRON DEVICES MEETING (IEDM) page： . 2017

Improved crystal quality of semipolar (10(1)over-bar3) GaN on Si(001) substrates using AlN/GaN superlattice interlayer International journal

Ho-Jun Lee, Si-Young Bae, Kaddour Lekhal, Tadashi Mitsunari, Akira Tamura, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 454 page： 114 - 120 2016.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The planar epitaxial growth of semipolar (10 (1) over bar3) GaN on a Si(001) substrate was performed on a directionally sputtered AlN buffer layer. Three types of interlayers, i.e., single AlN, double AlN, and a stack of AlN/GaN layers were grown by metalorganic chemical vapor deposition (MOCVD) to achieve high quality GaN films. The results for the stack of AlN/GaN layers provide highest crystal quality and optical properties for GaN. Comparing the top (Ga face) and bottom (N face) surfaces of grown semipolar (10 (1) over bar3) GaN confirms the defect density reduction that is due to the application of interlayers. Moreover, reduced inversion domain density on the bottom surface is attributed with the insertion of interlayers. Improving the quality of semipolar GaN on Si(001) substrates is expected to be useful for GaN/Si(001) integrated optoelectronics. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jcrysgro.2016.09.004

Controlled morphology of regular GaN microrod arrays by a selective area growth with HVPE International journal

Kaddour Lekhal, Si-Young Bae, Ho-Jun Lee, Tadashi Mitsunari, Akira Tamura, Manato Deki, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 447 page： 55 - 61 2016.8

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The selective area growth (SAG) of GaN was implemented on patterned GaN/sapphire templates by hydride vapor phase epitaxy (HVPE) to fabricate regular arrays of Ga-polar GaN microrods. The control of growth parameters such as H-2/N-2 carrier gas ratio, growth temperature, and absolute NH3/HCl gas flow resulted in changes in the growth morphology. In particular, for an optimized mixed-carrier gas ratio of H-2 to N-2, we achieved vertically well-aligned microrods. The topmost regions of the GaN microrods were terminated with pyramidal facets, indicating typical Ga polarity. The optical properties of the grown microrods were characterized by cathodoluminescence (CL) at a low temperature. This revealed that the GaN microrods had high crystal quality since they exhibited suppressed yellow luminescence as well as strong band edge emission. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jcrysgro.2016.05.008

Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study International journal

Shoko Nagai, Kiho Yamada, Akira Hirano, Masamichi Ippommatsu, Masahiro Ito, Naoki Morishima, Ko Aosaki, Yoshio Honda, Hiroshi Amano, Isamu Akasaki

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 8 ) 2016.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

To replace mercury lamps with AlGaN-based deep-ultraviolet (DUV) LEDs, a simple and low-cost package with increased light extraction efficiency (LEE) is indispensable. Therefore, resin encapsulation is considered to be a key technology. However, the photochemical reactions induced by DUV light cause serious problems, and conventional resins cannot be used. In the former part of this study, a comparison of a silicone resin and fluorine polymers was carried out in terms of their suitability for encapsulation, and we concluded that only one of the fluorine polymers can be used for encapsulation. In the latter part, the endurance of encapsulation using the selected fluorine polymer was investigated, and we confirmed that the selected fluorine polymer can guarantee a lifetime of over 6,000 h at a wavelength of 265nm. Furthermore, a 3 x 4 array module of encapsulated dies on a simple AlN submount was fabricated, demonstrating the possibility of W/cm(2)-class lighting. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.082101

Evaluation of excess In during metal organic vapor-phase epitaxy growth of InGaN by monitoring via in situ laser scattering International journal

Tetsuya Yamamoto, Akira Tamura, Shigeyoshi Usami, Tadashi Mitsunari, Kentaro Nagamatsu, Shugo Nitta, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Using an in situ laser absorption and scattering method, the surface roughness and incorporation of In in InGaN layers grown by metal organic vapor-phase epitaxy (MOVPE) were monitored. We observed that the laser light with energy higher than the GaN bandgap was fully absorbed in a GaN layer with a smooth film surface. On the other hand, we observed that the scattering laser light from the surface when the roughness of the InGaN surface increased owing to the formation of In droplets. Laser light with energy lower than the GaN bandgap was weakly absorbed by the GaN layer and was scattered at the back surface of the wafer. Furthermore, laser light intensity decreased during InGaN growth because of In incorporation. The threshold of trimethyl-In (TMIn) for the formation of In droplets as a function of growth temperature was determined using our in situ system. Moreover, we observed that the In droplets were removed by thermal or H-2 treatment. The results indicate that multiwavelength laser absorption and scattering enable the optimization of the growth conditions for In-rich InGaN. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FD03

Theoretical approach to surface reconstruction of InN(0001) during raised-pressure metalorganic vapor-phase epitaxy

Akira Kusaba, Yoshihiro Kangawa, Yoshio Honda, Hiroshi Amano, Koichi Kakimoto

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

We investigated the surface reconstruction of InN(0001) during raised-pressure metalorganic vapor-phase epitaxy using an ab initio-based approach. We observed that the reconstructed structure changes from In-rich surfaces such as In bilayer and monolayer surfaces to an ideal surface with increasing growth temperature. In addition, we investigated the effects of surface reconstruction on the growth process using a newly improved thermodynamic analysis method. Although no barrier is present in the growth reaction when the In-rich surfaces appear, the results suggest that the surface phase acts as a barrier in the growth reaction when the ideal surface appears. Furthermore, we discuss the growth conditions that enable high-temperature growth with a smooth reaction path. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FM01

Study of radiation detection properties of GaN pn diode

Mutsuhito Sugiura, Maki Kushimoto, Tadashi Mitsunari, Kohei Yamashita, Yoshio Honda, Hiroshi Amano, Yoku Inoue, Hidenori Mimura, Toru Aoki, Takayuki Nakano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Recently, GaN, which has remarkable properties as a material for optical devices and high-power electron devices, has also attracted attention as a material for radiation detectors. We previously suggested the use of BGaN as a neutron detector material. However, the radiation detection characteristics of GaN itself are not yet adequately understood. For realizing a BGaN neutron detector, the understanding of the radiation detection characteristics of GaN, which is a base material of the neutron detector, is important. In this study, we evaluated the radiation detection characteristics of GaN. We performed I-V and energy spectrum measurements under alpha ray, gamma ray, and thermal neutron irradiations to characterize the radiation detection characteristics of a GaN diode. The obtained results indicate that GaN is an effective material for our proposed new BGaN-based neutron detector. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FJ02

Structural and optical study of core-shell InGaN layers of nanorod arrays with multiple stacks of InGaN/GaN superlattices for absorption of longer solar spectrum International journal

Si-Young Bae, Byung Oh Jung, Kaddour Lekhal, Dong-Seon Lee, Manato Deki, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

We report on the material and optical properties of core-shell InGaN layers grown on GaN nanorod arrays. The core-shell InGaN layers were well grown on polarization-reduced surfaces such as semipolar pyramids and nonpolar sidewalls. In addition, to compensate the biaxial strain between GaN and InGaN layers, we grew interlayers underneath a thick InGaN layer. Here, the interlayers were composed of multiple superlattice structures. We could observe that the indium composition of core-shell InGaN structures increased with the number of interlayers. This indicates that the absorption energy band of InGaN alloys can be better matched to the spectral irradiance of the solar spectrum in nature. We also implemented a simulation of Ga-polar and nonpolar InGaN-based solar cells based on the indium composition obtained from the experiments. The result showed that nonpolar InGaN solar cells had a much higher efficiency than Ga-polar InGaN solar cells with the same thickness of the absorption layer. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FG03

Selective-area growth of GaN microrods on strain-induced templates by hydride vapor phase epitaxy International journal

Kaddour Lekhal, Si-Young Bae, Ho-Jun Lee, Tadashi Mitsunari, Akira Tamura, Manato Deki, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

In this paper, we discuss the influence of parameters such as type of carrier gas and NH3/HCl flow ratio on the growth of vertical GaN microstructures by selective-area growth (SAG) hydride vapor phase epitaxy (HVPE). On various strain-induced templates such as GaN/sapphire, GaN/Si, and AlN/Si, regular arrays of Ga-polar GaN microrods were properly achieved by adjusting the growth parameters. The photoluminescence and micro-Raman measurements reveal not only the crystal quality of the GaN microrods but also strain distribution. These results will give insight into the control of the morphology of GaN microrods in terms of the strain induced from templates in SAG-HVPE. The precisely controlled arrays of GaN microrods can be used for next-generation light-emitting diodes (LEDs) by realizing InGaN/GaN multi-quantum wells (MQWs) with a radial structure. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FF03

Preflow trimethylaluminum treatment effect on GaN growth on SiC with an ultrathin interlayer International journal

Zheng Sun, Kentaro Nagamatsu, Marc Olsson, Peifeng Song, Manato Deki, Shugo Nitta, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Previously, we reported a growth method for GaN on SiC by metalorganic vapor phase epitaxy. By using a preflow trimethylaluminum treatment, the poor wetting problem of gallium on the SiC surface was alleviated, resulting in a 1.2-mu m-thick crack-free GaN grown on an on-axis 6H-SiC(0001) substrate via an ultrathin AlGaN interlayer. In this study, the impact of the preflow trimethylaluminum treatment time is investigated to understand why a crack-free epilayer was realized. To demonstrate the electrical performance of devices formed by our technique, GaN/SiC vertical Schottky barrier diodes were fabricated and compared with GaN/AlN/SiC and GaN/GaN vertical Schottky barrier diodes. Compared with diodes including a high-resistance AlN interlayer, the series resistance of GaN/SiC Schottky barrier diodes incorporating the ultrathin interlayer with 5 s of TMAl treatment showed a marked reduction from 4.0 x 10(7) to 2.0 x 10(-1) Omega.cm(2). The ultrathin interlayer growth technique is expected to be applied in future GaN/SiC hybrid high-power and high-frequency devices. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FB06

Observation of relaxation time of surface charge limit for InGaN photocathodes with negative electron affinity International journal

Daiki Sato, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

A thin p-type InGaN with a negative electron affinity (NEA) surface was used to measure the relaxation time of a surface charge limit (SCL) by irradiating rectangular laser beam pulses at changing time interval. The p-type InGaN film was grown by metal organic vapor phase epitaxy and the NEA activation was performed after the sample was heat cleaned. 13 nC per pulse with 10ms width was obtained from the InGaN photocathode. The current decreased exponentially from the beginning of the pulse. The initial current value after the laser irradiation decreased with the time interval. As a result, the SCL relaxation time was estimated through the InGaN photocathode measurements at 100 ms. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FH05

Growth of semipolar (1(1)over-bar01) high-indium-content InGaN quantum wells using InGaN tilting layer on Si(001) International journal

Maki Kushimoto, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Low-toxity high-In-content InGaN is an attractive option for short-distance communications through plastic optical fibers because its performance is only slightly affected by temperature. However, its fabrication on the c-plane is impaired by In droplets and V pits, which form at low-growth temperature. On the other hand, unlike the c-plane, (1 (1) over bar 01) InGaN relaxes with tilting. Therefore, in this study, we first grew a high-In-content InGaN single layer, and then we fabricated an InGaN tilting layer between (1 (1) over bar 01) InGaN-based multiple quantum wells (MQWs) and GaN stripes/(001) Si. The emission wavelength increased with the InGaN tilting layer's growth time because the strain was relaxed by misfit dislocations at the heterointerface. This layer also extended the emission peak of InGaN/GaN MQWs and increased the photoluminescence intensity with respect to that of a single-layered InGaN. Therefore, the InGaN tilting layer is effective for growing high-In-content (1 (1) over bar 01) InGaN MQWs. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FA10

Growth of AlN layer on patterned sapphire substrate by hydride vapor phase epitaxy International journal

Gang Seok Lee, Chanmi Lee, Hunsoo Jeon, Chanbin Lee, Sung Geun Bae, Hyung Soo Ahn, Min Yang, Sam Nyung Yi, Young Moon Yu, Jae Hak Lee, Yoshio Honda, Nobuhiko Sawaki, Suck-Whan Kim

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 5 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Even though a patterned sapphire substrate (PSS) has been used for the growth of a high-quality epilayer because of its many advantages, it has not been successfully used to grow an AlN epilayer for ultraviolet (UV) light-emitting diodes (LEDs) on a PSS up to now. We report the growth of a high-quality AlN epilayer on a PSS, as a substrate for the manufacture of UV LEDs, by hydride vapor phase epitaxy (HVPE). The X-ray diffraction (XRD) peaks for the AlN epilayer grown on the PSS indicate that crystalline AlN with a wurtzite structure was grown successfully on the PSS. Furthermore, HVPE combining both in situ HVPE technology and liquid-phase epitaxy (LPE) using a mixed source is proposed as a novel method for the growth of a flat AlN epilayer on a PSS. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.05FC02

Emission Characteristics of InGaN/GaN Core-Shell Nanorods Embedded in a 3D Light-Emitting Diode International journal

Byung Oh Jung, Si-Young Bae, Seunga Lee, Sang Yun Kim, Jeong Yong Lee, Yoshio Honda, Hiroshi Amano

NANOSCALE RESEARCH LETTERS Vol. 11 ( 1 ) page： 215 2016.4

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

We report the selective-area growth of a gallium nitride (GaN)-nanorod-based InGaN/GaN multiple-quantum-well (MQW) core-shell structure embedded in a three-dimensional (3D) light-emitting diode (LED) grown by metalorganic chemical vapor deposition (MOCVD) and its optical analysis. High-resolution transmission electron microscopy (HR-TEM) observation revealed the high quality of the GaN nanorods and the position dependence of the structural properties of the InGaN/GaN MQWs on multiple facets. The excitation and temperature dependences of photoluminescence (PL) revealed the m-plane emission behaviors of the InGaN/GaN core-shell nanorods. The electroluminescence (EL) of the InGaN/GaN core-shell-nanorod-embedded 3D LED changed color from green to blue with increasing injection current. This phenomenon was mainly due to the energy gradient and deep localization of the indium in the selectively grown InGaN/GaN core-shell MQWs on the 3D architecture.

DOI： 10.1186/s11671-016-1441-6

Study of enhanced photovoltaic behavior in InGaN-based solar cells by using SiNx insertion layer: Influence of dislocations

PubMed

Seunga Lee, Yoshio Honda, Hiroshi Amano, Jongjin Jang, Okhyun Nam

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 3 ) 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Using a SiNx insertion layer to reduce dislocations, enhanced photovoltaic properties could be obtained in p-i-n InGaN/GaN heterojunction solar cell. To investigate the influence of the dislocations on the photovoltaic behaviors, a sample grown without SiNx insertion layer was identically prepared for comparison. From optical properties measurements, the reduction in the number of non-radiative centers and a stronger In localization effect was shown in the sample with SiNx insertion layer. However, the quantum confined stark effect was almost negligible in both the samples. Electrical properties measurement showed reduced saturation current and increased shunt resistance in the sample with SiNx insertion layer due to the reduced dislocation density. By comparing these results and using a numerical model, the influence of the dislocation density on the different photovoltaic properties such as open-circuit voltage and fill factor has been confirmed. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.030306

Effect of piezoelectric field on carrier dynamics in InGaN-based solar cells International journal

Seunga Lee, Yoshio Honda, Hiroshi Amano

JOURNAL OF PHYSICS D-APPLIED PHYSICS Vol. 49 ( 2 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

To understand the effect of piezoelectric fields on carrier dynamics, we numerically investigated a simple p-GaN/i-InxGa1-xN/n-GaN solar cell structure. A reliable simulation model was obtained by comparing the experimental and simulated results in advance. The same p-i-n InGaN structures were re-simulated with and without the piezoelectric field effect, as spontaneous polarization remained unchanged. The sample with the piezoelectric field effect showed higher short current density (J(sc)), a staircase-like feature in its I-V curve, and higher open circuit voltage (V-oc) with a lower fill factor (F.F.) and reduced conversion efficiency (C.E.) than the sample with no piezoelectric fields. In addition, with increasing In fraction (x), the V-oc value gradually increased while the J(sc) value significantly decreased, correspondingly leading to a reduction in C.E. and F.F. values of the structure with the piezoelectric field effect. To solve the current loss problem, we applied various piezoelectric field elimination techniques to the simulated structures.

DOI： 10.1088/0022-3727/49/2/025103

The interface analysis of GaN grown on 0 degrees off 6H-SiC with an ultra-thin buffer layer

Zheng Sun, Akio Ohta, Seiichi Miyazaki, Kentaro Nagamatsu, Hojun Lee, Marc Olsson, Zheng Ye, Manato Deki, Yoshio Honda, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 55 ( 1 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Previously, we reported a growth method by metalorganic vapor phase epitaxy using a single two- dimensional growth step, resulting in 1.2-mu m crack-free GaN directly grown on 6H-SiC substrate. The introduction of Al-treatment prior to the standard GaN growth step resulted in improved surface wetting of gallium on the SiC substrate. Transmission electron microscope and energy dispersive spectrometer analysis of the epitaxial interface to the SiC determined that an ultra-thin AlGaN interlayer had formed measuring around 2-3 nm. We expect our growth technique can be applied to the fabrication of GaN/SiC high frequency and high power devices. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.010303

Development of AlGaN-based deep-ultraviolet (DUV) LEDs focusing on the fluorine resin encapsulation and the prospect of the practical applications International journal

Akira Hirano, Yosuke Nagasawa, Masamichi Iypommatsu, Ko Aosaki, Yoshio Honda, Hiroshi Amano, Isamu Akasaki

UV and Higher Energy Photonics: From Materials to Applications Vol. 9926 2016

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPIE-INT SOC OPTICAL ENGINEERING

AlGaN-based LEDs are expected to be useful for sterilization, deodorization, photochemical applications such as UV curing and UV printing, medical applications such as phototherapy, and sensing. Today, it has become clear that efficient AlGaN-based LED dies are producible between 355 and 250 nm with an external quantum efficiency (EQE) of 3% on flat sapphire. These dies were realized on flat sapphire without using a special technique, i.e., reduction in threading dislocation density or light extraction enhancement techniques such as the use of a photonic crystal or a patterned sapphire substrate. Despite the limited light extraction efficiency of about 8% owing to light absorption at a thick p-GaN contact layer, high EQEs of approximately 6% has been reproducible between 300 and 280 nm without using special techniques. Moreover, an EQE of 3.9% has been shown at 271 nm, despite the smaller current injection efficiency (CIE). The high EQEs are thought to correspond to the high internal quantum efficiency (IQE), indicating a small room for improving IQE. Accordingly, resin encapsulation on a simple submount is strongly desired. Recently, we have succeeded in demonstrating fluorine resin encapsulation on a ceramic sheet (chip-on-board, COB) that is mass-producible. Furthermore, the molecular structure of a resin with a durability of more than 10,000 h is explained in this paper from the photochemical viewpoint. Thus, the key technologies of AlGaN-based DUV-LEDs having an EQE of 10% within a reasonable production cost have been established. The achieved efficiency makes AlGaN-based DUV-LEDs comparable to high-pressure mercury lamps.

DOI： 10.1117/12.2235398

Highly elongated vertical GaN nanorod arrays on Si substrates with an AlN seed layer by pulsed-mode metal-organic vapor deposition International journal

Si-Young Bae, Byung Oh Jung, Kaddour Lekhal, Sang Yun Kim, Jeong Yong Lee, Dong-Seon Lee, Manato Deki, Yoshio Honda, Hiroshi Amano

CRYSTENGCOMM Vol. 18 ( 9 ) page： 1505 - 1514 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

To extend the availability of nanostructure-based optoelectronic applications, vertically elongated nanorods with precisely controlled morphology are required. For group III nitrides, pulsed-mode growth has recently been reported as an effective method for growing nanorod arrays with geometric precision. Here, we demonstrated the growth of arrays of highly elongated nanorods on Si substrates by metal-organic chemical vapor deposition using a pulsed-mode approach. Unlike the thick and high (or middle)-quality GaN templates normally used, nanorod growth was performed on an ultrathin and low-quality AlN/Si platform. Using kinetically controlled growth conditions and a patterning process, exceptionally long GaN nanorods were achieved with high geometric precision. The grown nanorods showed considerably improved optical and structural properties while remaining in uniform arrays. This approach can be used with a variety of materials to obtain nanorods with high quality, high uniformity, and high aspect ratio, and it can also serve as an effective fabrication method for InAlGaN-alloyed core/shell nanostructures for optoelectronic nano-devices with ultrahigh efficiency.

DOI： 10.1039/c5ce02056e

Excitation density dependence of radiative and nonradiative recombination lifetimes in InGaN/GaN multiple quantum wells International journal

Hideaki Murotani, Yoichi Yamada, Yoshio Honda, Hiroshi Amano

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Vol. 252 ( 5 ) page： 940 - 945 2015.5

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The optical properties of InGaN/GaN multiple quantum wells (MQWs) have been studied by means of photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectroscopy. The radiative and nonradiative recombination lifetimes were evaluated as a function of the excitation energy density. The radiative recombination lifetime decreased and subsequently reached a nearly constant value with increasing excitation energy density, which was attributed to screening of internal electric fields by photoexcited carriers. On the other hand, the nonradiative recombination lifetime increased and subsequently decreased with increasing excitation energy density. The initial increase in the nonradiative recombination lifetime could be attributed to saturation of nonradiative recombination centers with photoexcited carriers. The nonradiative recombination lifetime was found to decrease to a considerably weaker extent than that expected for the Auger recombination process of free carriers. This indicated that the decrease in the internal quantum efficiency (IQE) at high carrier densities could not be explained only by the Auger recombination process of free carriers. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

DOI： 10.1002/pssb.201451491

Optically pumped lasing properties of (1-101) InGaN/GaN stripe multiquantum wells with ridge cavity structure on patterned (001) Si substrates Reviewed

Vol. 8 ( 2 ) page： 022702 2015.2

Optically pumped lasing properties of (1-101) InGaN/GaN stripe multiquantum wells with ridge cavity structure on patterned (001) Si substrates

Maki Kushimoto, Tomoyuki Tanikawa, Yoshio Honda, Hiroshi Amano

Applied Physics Express Vol. 8 ( 2 ) page： 022702 2015.2

Optically pumped lasing properties of (1(1)over-bar01) InGaN/GaN stripe multiquantum wells with ridge cavity structure on patterned (001) Si substrates International journal

Maki Kushimoto, Tomoyuki Tanikawa, Yoshio Honda, Hiroshi Amano

APPLIED PHYSICS EXPRESS Vol. 8 ( 2 ) 2015.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

We demonstrated lasing action and investigated the optical properties of (1 (1) over bar 01) multiquantum-well (MQW) stripe crystals on patterned (001) Si substrates. Longitudinal and higher order transverse modes were observed from a ridge waveguide structure. These results strongly suggest the possibility of fabricating (1 (1) over bar 01) InGaN MQW laser diodes on (001) Si. (C) 2015 The Japan Society of Applied Physics

DOI： 10.7567/APEX.8.022702

Highly ordered catalyst-free InGaN/GaN core-shell architecture arrays with expanded active area region International journal

Byung Oh Jung, Si-Young Bae, Sang Yun Kim, Seunga Lee, Jeong Yong Lee, Dong-Seon Lee, Yoshihiro Kato, Yoshio Honda, Hiroshi Amano

NANO ENERGY Vol. 11 page： 294 - 303 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Highly ordered, position-controlled gallium nitride (GaN) nanowire based multiple-quantum-wells (MQWs) core-shell architecture arrays are synthesized by metalorganic chemical vapor deposition (MOCVD). We investigate the possibility of using GaN nanowire arrays as a basal template for the growth of InxGa1-xN/GaN MQWs. The MQWs on three different crystal facets (c(-), m(-), and semipolar-plane) of GaN nanowire exhibit dissimilar structural properties. The structural characteristics of InGaN/GaN core-shell arrays are inspected by cross-sectional high-resolution transmission electron microscopy (HR-TEM). We also investigate the optical properties of MQW core-shell structure nanoarrays. The luminescent characteristics of InGaN/GaN core-shell structure arrays are determined by photoluminescence (PL) and cathodoluminescence (CL) measurements. The monochromatic CL images clearly show the light emission behavior of InGaN/GaN MQW coaxial structure. Two distinguishable light emission peaks were observed in the GaN nanowire based core-shell structure. The characteristic of light emission mainly depends on the properties of MQWs, which are generated from different crystal facets of GaN. In addition, the light emission intensity shows different behaviors depending on the area of the GaN nanowire m-plane. The results of this study suggest that GaN nanowire arrays can be used as a good alternative basal template for next-generation light-emitting diodes (LEDs). (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.nanoen.2014.11.003

Nature of yellow luminescence band in GaN grown on Si substrate International journal

Shogo Ito, Taihei Nakagita, Nobuhiko Sawaki, Hyung Soo Ahn, Masashi Irie, Toshiki Hikosaka, Yoshio Honda, Masahito Yamaguchi, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 53 ( 11 ) 2014.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

High-optical-quality GaN was grown on a (111) Si substrate by metal-organic vapor phase epitaxy using an AlInN buffer layer and an indium doped AlN nucleation layer. The photoluminescence spectra at room temperature showed a strong and narrow edge-emission peak and weak defect-related emission bands. We found four spectral peaks in the green and yellow luminescence bands at G(0): 514.5 nm (2.410 eV), G(1): 546.5nm (2.269 eV), Y-1: 553.5nm (2.240 eV), and Y-0: 584.5nm (2.121 eV), independent of the growth methods/conditions. The results suggest that the emission is associated with an intrinsic defect such as a Ga vacancy. (C) 2014 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.53.11RC02

P-GaN by Mg Ion Implantation for Power Device Applications

Quantum Efficiency and Life Time of GaN and InGaN with NEA-surface International journal

Sato Daiki, Nishitani Tomohiro, Maekawa Takuya, Honda Yoshio, Amano Hiroshi

IEICE technical report. Component parts and materials Vol. 114 ( 202 ) page： 49-54 - 54 2014.9

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

The photocathode using Negative Electron Affinity (NBA) surface on a semiconductor has been applied for science technologies such as an elemental particle experiment as an electron beam source. Yet, since NBA-surface is fragile, it is necessary to figure out how to make its life time longer in order to develop new technologies. Then, we realized that considering the band gap in semiconductor, the life time becomes longer as the negative affinity goes even smaller. Therefore, we produced the photocathodes using GaN and InGaN that have wider band gaps than that of GaAs. As a result, using GaN and InGaN, we gained 17 times and 7 times longer life time NEA-surface than that of GaAs, respectively. On the other hand, the result indicates that we can produce the NEA-surface with only cesium.

CiNii Books

P-GaN by Mg Ion Implantation for Power Device Applications (シリコン材料・デバイス) International journal

SUN Zheng, Olsson Marc, NAGAYAMA Tsutomu, HONDA Yoshio, AMANO Hiroshi

電子情報通信学会技術研究報告 = IEICE technical report : 信学技報 Vol. 114 ( 58 ) page： 109-112 - 112 2014.5

Language：English Publishing type：Research paper (scientific journal) Publisher：一般社団法人電子情報通信学会

We realized p-GaN by high temperature Mg ion implantation with pre-sputter(PS) technique. Due to the new PS technique and high temperature implantation, ion implantation damage was greatly reduced. This soft implantation made the post anneal more effectively to recover the implantation damage and activate the implanted Mg ions. We believe this p-GaN by Mg ion implantation will contribute to GaN to enter high output power device application field.

SUN Zheng, Olsson Marc, NAGAYAMA Tsutomu, HONDA Yoshio, AMANO Hiroshi

IEICE technical report. Component parts and materials Vol. 114 ( 57 ) page： 109-112 - 112 2014.5

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

CiNii Books

P-GaN by Mg Ion Implantation for Power Device Applications

SUN Zheng, Olsson Marc, NAGAYAMA Tsutomu, HONDA Yoshio, AMANO Hiroshi

IEICE technical report. Electron devices Vol. 114 ( 56 ) page： 109-112 - 112 2014.5

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

CiNii Books

Characterization of nonpolar a-plane InGaN/GaN multiple quantum well using double nanopillar SiO2 mask International journal

Ji-Su Son, Yoshio Honda, Masahito Yamaguchi, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 53 ( 5 ) 2014.5

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

The characteristics of nonpolar a-plane (11 (2) over bar0) GaN (a-GaN) grown using single and double nanopillar SiO2 masks were investigated. The two nanopillar SiO2 masks were directly fabricated on an r-plane sapphire substrate and a-GaN by the epitaxial lateral overgrowth (ELOG) technique. Through the use of the single and double nanopillar SiO2 masks, the crystalline quality and optical properties of a-GaN were markedly improved because of the nanoscale ELOG effect and a number of voids in the single and double nanopillar SiO2 mask areas in comparison with the planar sample. The submicron pit densities of the planar, single, and double nanopillar mask samples were similar to 2 x 10(9), similar to 7 x 10(8), and similar to 4 x 10(8) cm(-2), respectively. The internal quantum efficiency (IQE) values at room temperature of three-period InGaN/GaN multiple quantum wells (MQWs) grown using the planar, single, and double nanopillar masks were 45, 60, and 68% at a carrier concentration of 1.0 x 10(18) cm(-3), respectively. (C) 2014 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.53.05FL01

In situ X-ray investigation of changing barrier growth temperatures on InGaN single quantum wells in metal-organic vapor phase epitaxy International journal

Guangxu Ju, Yoshio Honda, Masao Tabuchi, Yoshikazu Takeda, Hiroshi Amano

JOURNAL OF APPLIED PHYSICS Vol. 115 ( 9 ) 2014.3

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

The effects of GaN quantum barriers with changing growth temperatures on the interfacial characteristics of GaN/InGaN single quantum well (SQW) grown on GaN templates by metalorganic vapour phase epitaxy were in situ investigated by X-ray crystal truncation rod (CTR) scattering and X-ray reflectivity measurements at growth temperature using a laboratory level X-ray diffractometer. Comparing the curve-fitting results of X-ray CTR scattering spectra obtained at growth temperature with that at room temperature, the InxGa1-xN with indium composition less than 0.11 was stabile of the indium distribution at the interface during the whole growth processes. By using several monolayers thickness GaN capping layer to protect the InGaN well layer within temperature-ramping process, the interfacial structure of the GaN/InGaN SQW was drastically improved on the basis of the curve-fitting results of X-ray CTR scattering spectra, and the narrow full width at half-maximum and strong luminous intensity were observed in room temperature photoluminescence spectra. (C) 2014 AIP Publishing LLC.

DOI： 10.1063/1.4867640

Growth of InGaN/GaN multiple quantum wells on size-controllable nanopyramid arrays International journal

Cao Miao, Yoshio Honda, Masahito Yamaguchi, Hiroshi Amano

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 53 ( 3 ) 2014.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Regularly distributed nanopyramid arrays with a highly uniform size were grown by selective-area growth. The nanopyramid size could be tuned by varying the growth time. Two emission peaks were observed from multiple quantum wells grown on the nanopyramids. The longer-wavelength peak originated from the apexes of pyramids with threefold symmetry. High-density stacking faults observed at these triangular apexes might be responsible for the higher indium incorporation. The formation of embedded voids inside the pyramids was explained by the different growth rates at the edge and center of the mask window caused by the low diffusion length. (C) 2014 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.53.030306

Novel activation process for Mg-implanted GaN International journal

Shin Hashimoto, Takao Nakamura, Yoshio Honda, Hiroshi Amano

JOURNAL OF CRYSTAL GROWTH Vol. 388 page： 112 - 115 2014.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

A novel activation process for Mg-implanted GaN was demonstrated. As opposed to the conventional thermal annealing process, an H-2/NH3 alternating supply annealing process achieved better optical activation, stronger near-ullraviolel luminescence and weaker yellow luminescence in the phololuminescence spectroscopy. After this process, small hexagonal hillocks were observed on the surface, which indicated that crystal regrowth was induced by this process, consisting of decomposition of GaN by H-2 supplies and re-crystallization by NH3 supplies. It was revealed that the implanted Mg could easily be located at the activation site by means of crystal regrowth by this process. (C) 2013 Elsevier B.V. All rights reserved

DOI： 10.1016/j.jcrysgro.2013.07.011

Growth of low-defect-density nonpolar a-plane GaN on r-plane sapphire using pulse NH3 interrupted etching International journal

Ji-Su Son, Yoshio Honda, Hiroshi Amano

OPTICS EXPRESS Vol. 22 ( 3 ) page： 3585 - 3592 2014.2

Language：English Publishing type：Research paper (scientific journal) Publisher：OPTICAL SOC AMER

Nonpolar a-plane (11-20) GaN (a-GaN) layers with low overall defect density and high crystalline quality were grown on r-plane sapphire substrates using etched a-GaN. The a-GaN layer was etched by pulse NH3 interrupted etching. Subsequently, a 2-mu m-thick Si-doped a-GaN layer was regrown on the etched a-GaN layer. A fully coalescent n-type a-GaN layer with a low threading dislocation density (similar to 7.5 x 10(8) cm(-2)) and a low basal stacking fault density (similar to 1.8 x 10(5) cm(-1)) was obtained. Compared with a planar sample, the full width at half maximum of the (11-20) X-ray rocking curve was significantly decreased to 518 arcsec along the c-axis direction and 562 arcsec along the m-axis direction. (C) 2014 Optical Society of America

DOI： 10.1364/OE.22.003585

PubMed

Reduction of efficiency droop in InGaN light-emitting diodes on low dislocation density GaN substrate Reviewed

page： 90030E-90030E-6 2014

Characterization of nonpolar a-plane InGaN/GaN multiple quantum well using double nanopillar SiO2 mask Reviewed

Vol. 53 ( 5S1 ) page： 05FL01 2014

Growth of low-defect-density nonpolar a-plane GaN on r-plane sapphire using pulse NH 3 interrupted etching Reviewed

Vol. 22 ( 3 ) page： 3585-3592 2014

Enhancement of light output power on GaN-based light-emitting diodes using two-direction stripe-patterned sapphire substrate Reviewed

Vol. 11 ( 3‐4 ) page： 722-725 2014

Growth of InGaN/GaN multiple quantum wells on size-controllable nanopyramid arrays Reviewed

Vol. 53 ( 3 ) page： 30306 2014

Morphology development of GaN nanowires using a pulsed-mode MOCVD growth technique Reviewed

Vol. 16 ( 11 ) page： 2273-2282 2014

X-ray investigations of GaInN single quantum wells grown by atomic layer epitaxy and metalorganic vapor phase epitaxy Reviewed

Vol. 11 ( 3‐4 ) page： 393-396 2014

In situ X-ray investigation of changing barrier growth temperatures on InGaN single quantum wells in metal-organic vapor phase epitaxy Reviewed

Vol. 115 ( 9 ) page： 94906 2014

Novel activation process for Mg-implanted GaN Reviewed

Vol. 388 page： 112-115 2014

Recombination dynamics and internal quantum efficiency in InGaN nanowires Reviewed

Vol. 11 ( 3-4 ) page： 652 - 655 2014

X-ray investigations of GaInN single quantum wells grown by atomic layer epitaxy and metalorganic vapor phase epitaxy Reviewed

Vol. 11 ( 3-4 ) page： 393 - 396 2014

Enhancement of light output power on GaN-based light-emitting diodes using two-direction stripe-patterned sapphire substrate Reviewed International journal

Vol. 11 ( 3-4 ) page： 722 - 725 2014

Reduction of efficiency droop in InGaN light-emitting diodes on low dislocation density GaN substrate International journal

Kouhei Yamashita, Tomohiko Sugiyama, Makoto Iwai, Yoshio Honda, Takashi Yoshino, Hiroshi Amano

LIGHT-EMITTING DIODES: MATERIALS, DEVICES, AND APPLICATIONS FOR SOLID STATE LIGHTING XVIII Vol. 9003 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPIE-INT SOC OPTICAL ENGINEERING

A GaN layer of 20 mu m thickness grown by the liquid-phase epitaxy on c-plane sapphire was used as a template for the growth of blue light-emitting diodes (LEDs) with emission peak wavelengths of about 450 nm. As the underlying layer of the active region, an InGaN/GaN superlattice or two pairs of 100 nm undoped GaN and 20 nm GaN: Si layers on an n-type GaN: Si layer was found to be effective for reducing the forward voltage. By optimizing the multiple-quantumwell structure, LEDs having a 2.5-nm-thick InGaN well and 5-nm-thick GaN barrier exhibited the highest internal quantum efficiency (IQE) at both low and high currents. This IQE was much higher than that of LEDs on a sapphire substrate. The IQE of LEDs using the liquid-phase GaN grown on sapphire substrate exceeded more than 75% at a forward current density of over 200 A/cm(2).

DOI： 10.1117/12.2038764

Morphology development of GaN nanowires using a pulsed-mode MOCVD growth technique International journal

Byung Oh Jung, Si-Young Bae, Yoshihiro Kato, Masataka Imura, Dong-Seon Lee, Yoshio Honda, Hiroshi Amano

CRYSTENGCOMM Vol. 16 ( 11 ) page： 2273 - 2282 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

In this paper, we demonstrate a scalable process for the precise position-controlled selective growth of GaN nanowire arrays by metalorganic chemical vapor deposition (MOCVD) using a pulsed-mode growth technique. The location, orientation, length, and diameter of each GaN nanowire are controlled via pulsed-mode growth parameters such as growth temperature and precursor injection and interruption durations. The diameter and length of each GaN nanowire are in the ranges of more than 240 nm and 250-1250 nm, respectively, with different vertical-to-lateral aspect ratios that depend on the growth temperature. Also, it is found that a higher growth temperature helps increase the vertical growth rate and reduces the lateral growth rate of GaN nanowire arrays. Furthermore, in the case of longer TMGa injection duration, the Ga-rich region allows the higher lateral growth rate of GaN nanostructures, which leads to a transition in the morphology from nanowires to a thin film, while in the case of longer NH3 injection duration, the surface morphology changes from nanowires to pyramidal structures. In addition, the surface structure can also be controlled by varying the precursor interruption duration. Finally, we report and discuss a growth model for GaN nanowire arrays under pulsed-mode MOCVD growth.

DOI： 10.1039/c3ce42266f