Faculty Profiles - HONDA, Yoshio

Papers - HONDA, Yoshio

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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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

PubMed

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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

Web of Science

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.

P-GaN by Mg Ion Implantation for Power Device Applications

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

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Papers - HONDA, Yoshio