Faculty Profiles - AMANO, Hiroshi

Papers - AMANO, Hiroshi

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

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

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

Language：English Publishing type：Research paper (scientific journal) Publisher：Physica Status Solidi (A) Applications and Materials Science

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

Web of Science

Scopus

Role of threading dislocations in strain relaxation during GaInN growth monitored by real-time X-ray reflectivity Reviewed

Guangxu Ju, Masao Tabuchi, Yoshikazu Takeda, and Hiroshi Amano

Applied Physics Letters Vol. 110 ( 26 ) page： 262105/1-5 2017.6

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

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

Journal of Crystal Growth Vol. 468 page： 866-869 2017.6

Effect of V/III ratio on the surface morphology and electrical properties of m–plane ( 101¯0 ) GaN homoepitaxial layers Reviewed

Vol. 468 page： 552-556 2017.6

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

We have investigated the effect of V/III ratio on the surface morphology, impurity concentration and electrical properties of m–plane (101¯0) 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/cm2 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

Annealing eﬀect on threading dislocations in a GaN grown on Si substrate Reviewed

Vol. 468 page： 835-838 2017.6

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

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 °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 °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

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

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

Journal of Crystal Growth Vol. 468 page： 547-551 2017.6

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

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

Journal of Crystal Growth Vol. 468 page： 110-113 2017.6

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

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

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

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Crystal Growth

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

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Scopus

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

Michiko Kaneda, Cyril Pernot, Yosuke Nagasawa, Akira Hirano, Masamichi Ippommatsu, Yoshio Honda, Hiroshi Amano, and Isamu Akasaki

Japanese Journal of Applied Physics Vol. 56 page： 061002 2017.5

III-nitride core-shell nanorod array on quartz substrates Open Access

Si-Young Bae, Jung-Wook Min, Hyeong-Yong Hwang, Kaddour Lekhal, Ho-Jun Lee, Young-Dahl Jho, Dong-Seon Lee, Yong-Tak Lee, Nobuyuki Ikarashi, Yoshio Honda, Hiroshi Amano

SCIENTIFIC REPORTS Vol. 7 page： 45345 2017.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

We report the fabrication of near-vertically elongated GaN nanorods on quartz substrates. To control the preferred orientation and length of individual GaN nanorods, we combined molecular beam epitaxy (MBE) with pulsed-mode metal-organic chemical vapor deposition (MOCVD). The MBE-grown buffer layer was composed of GaN nanograins exhibiting an ordered surface and preferred orientation along the surface normal direction. Position-controlled growth of the GaN nanorods was achieved by selective-area growth using MOCVD. Simultaneously, the GaN nanorods were elongated by the pulsed-mode growth. The microstructural and optical properties of both GaN nanorods and InGaN/GaN core-shell nanorods were then investigated. The nanorods were highly crystalline and the core-shell structures exhibited optical emission properties, indicating the feasibility of fabricating III-nitride nano-optoelectronic devices on amorphous substrates.

DOI： 10.1038/srep45345

Investigation of reduction of light absorption at p-side toward UV emitting devices

Yasuda Toshiki, Kuwabara Natsuko, Takeuchi Tetsuya, Iwaya Motoaki, Kamiyama Satoshi, Akasaki Isamu, Amano Hiroshi

JSAP Annual Meetings Extended Abstracts Vol. 2017.1 ( 0 ) page： 3400 - 3400 2017.3

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

Relationship between lattice relaxation and electrical properties in polarization doping of graded AlGaN with high AlN mole fraction on AlGaN template

Yasuda Toshiki, Takeuchi Tetsuya, Iwaya Motoaki, Kamiyama Satoshi, Akasaki Isamu, Amano Hiroshi

APPLIED PHYSICS EXPRESS Vol. 10 ( 2 ) 2017.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Physics Express

We investigated polarization doping for hole generation in abrupt and graded GaN/Al0.7Ga0.3N interfaces on Al0.99Ga0.01N templates. The abrupt interface exhibited hole generation, whereas the graded interface exhibited electron generation. In the graded AlxGa1%xN (x = 0.65-0), a graded part with an AlN mole fraction ranging from 0.2 to 0 showed a large relaxation. Theoretical estimation revealed that this part contained positive polarization charges, accumulating electrons. Via Mg doping in the graded AlGaN layer, we obtained a high hole concentration of 3 ' 1013cm%2. These results indicate that understanding the relaxation conditions in the graded layer is indispensable for polarization doping.

DOI： 10.7567/APEX.10.025502

Web of Science

Scopus

Relationship between lattice relaxation and electrical properties in polarization doping of graded AlGaN with high AlN mole fraction on AlGaN template Reviewed

Toshiki Yasuda, Tetsuya Takeuchi, Motoaki Iwaya, Satoshi Kamiyama, Isamu Akasaki and Hiroshi Amano

Applied Physics Express Vol. 10 page： 025502 2017.1

From the dawn of gan-based light-emitting devices to the present day

Amano H.

Handbook of Solid-State Lighting and LEDs page： 3-12 2017.1

High quality Al0.99Ga0.01N layers on sapphire substrates grown at 1150 degrees C by metalorganic vapor phase epitaxy

Katsuno Shota, Yasuda Toshiki, Hagiwara Koudai, Koide Norikatsu, Iwaya Motoaki, Takeuchi Tetsuya, Kamiyama Satoshi, Akasaki Isamu, Amano Hiroshi

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

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

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

Physica Status Solidi b Vol. 253 page： 1700387(1-7) 2017

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

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 6.7E7 cm2. 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

Open Access

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

Progress and prospect of growth of wide-band-gap group III nitrides

Hiroshi Amano

Topics in Applied Physics Vol. 133 page： 1 - 9 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Springer Verlag

GaAs, InP, and their related compound semiconductors can be grown on native substrates, whereas such growth was not possible for group III nitride semiconductors in the 1970s and 1980s. Despite this drawback, researchers were able to use novel functions of group III nitride semiconductors by growing their thin films on nonnative substrates such as sapphire SiC and Si.

DOI： 10.1007/978-981-10-3755-9_1

Web of Science

Scopus

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Papers - AMANO, Hiroshi