Faculty Profiles - HONDA, Yoshio

Papers - HONDA, Yoshio

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

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

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

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

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

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

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

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