研究者詳細 - 天野　浩

論文 - 天野　浩

分割表示 855 件中 201 - 220 件目／全件表示 >>

Using SiO2-Based Distributed Bragg Reflector to Improve the Performance of AlGaInP-Based Red Micro-Light Emitting Diode

Lee Sang-Youl, Moon Ji Hyung, Moon Yong-Tae, Choi Byoungjun, Oh Jeong-Tak, Jeong Hwan-Hee, Seong Tae-Yeon, Amano Hiroshi

ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY 9 巻 ( 3 ) 頁： 036002 2020年2月

Using SiO<inf>2</inf>-based distributed Bragg reflector to improve the performance of AlGaInP-based red micro-light emitting diode

Lee S.Y., Moon J.H., Moon Y.T., Choi B., Oh J.T., Jeong H.H., Seong T.Y., Amano H.

ECS Journal of Solid State Science and Technology 9 巻 ( 3 ) 2020年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：ECS Journal of Solid State Science and Technology

We have investigated how different types of the reflectors affected the optical and electrical performance of AlGaInP-based micro-LEDs. Simulations showed that the AlGaAs-based epitaxial distributed Bragg reflector (DBR) had a stopband at the 610–624 nm region with reflectivity of 90%, the SiO2/TiO2 dielectric DBR gave a stopband at the 580–770 nm range with a maximum reflectivity of 99%, and the ITO/Ag metal reflector exhibited reflectivity of 90% across the 400–800 nm region. All micro-LEDs gave forward voltages of 1.895–1.960 V at 20 μA. The micro-LEDs with the dielectric DBR and metal reflector yielded 31% and 13% higher light output at 20 μA than that with the epitaxial DBR, respectively. All of the micro-LEDs contained a shoulder peak at approximately 615 nm in their electroluminescence spectra. Ray-tracing simulations exhibited that the micro-LEDs with the dielectric DBR and metal reflector produced 26% and 22% higher total light output power than the one with the epitaxial DBR, respectively. It was also shown that for the micro-LEDs with the metal reflector, some of the micro-LEDs were detached from the metal reflectors due to the interfacial voids induced as a result of agglomeration of Ag layer during fabrication process.

DOI： 10.1149/2162-8777/ab74c3/pdf

Scopus

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

Sato, D; Honda, A; Koizumi, A; Nishitani, T; Honda, Y; Amano, H

MICROELECTRONIC ENGINEERING 223 巻頁： 111229 2020年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Microelectronic Engineering

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

Web of Science

Scopus

Effect of unevenly-distributed V pits on the optical and electrical characteristics of green micro-light emitting diode

Lee Da-Hoon, Kang Daesung, Seong Tae-Yeon, Kneissl Michael, Amano Hiroshi

JOURNAL OF PHYSICS D-APPLIED PHYSICS 53 巻 ( 4 ) 頁： 045106 2020年1月

Oblique-Angle Deposited SiO2/Al Omnidirectional Reflector for Enhancing the Performance of AlGaN-Based Ultraviolet Light-Emitting Diod

Jeongwon Lee, Tae-Yeon Seong, Hiroshi Amano

ECS Journal of Solid State Science and Technology 9 巻 ( 2 ) 2020年1月

Oblique-Angle Deposited SiO2/Al Omnidirectional Reflector for Enhancing the Performance of AlGaN-Based Ultraviolet Light-Emitting Diode

Jeongwon Lee, Tae-Yeon Seong, Hiroshi Amano

ECS Journal of Solid State Science and Technology 9 巻 ( 2 ) 頁： 026005 2020年1月

Heavy Mg Doping to Form Reliable Rh Reflective Ohmic Contact for 278 nm Deep Ultraviolet AlGaN-Based Light-Emitting Diodes

Lee Sang-Youl, Han Dae-Seob, Lee Yong-Gyeong, Choi Kwang-Ki, Oh Jeong-Tak, Jeong Hwan-Hee, Seong Tae-Yeon, Amano Hiroshi

ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY 9 巻 ( 6 ) 頁： 065016 2020年1月

Improved breakdown voltage in vertical GaN Schottky barrier diodes on free-standing GaN with Mg-compensated drift layer

Abhinay, S; Arulkumaran, S; Ng, GI; Ranjan, K; Deki, M; Nitta, S; Honda, Y; Amano, H

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( 1 ) 頁： 010906 2020年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Vertical Schottky barrier diodes (SBD) were fabricated on 1a 5 μm thick GaN drift layer (DL) with and without Mg-compensation grown by metal organic chemical vapour deposition on free-standing hydride vapour phase epitaxy grown substrate. The SBDs with Mg-compensated DL exhibited ∼3.4 × higher breakdown voltage (V bd) than the SBDs with conventional DL. The activation energy of 0.43 eV from the SBD with Mg-compensated DL can be correlated to the presence of Mg. The reverse current conduction mechanism of SBDs with Mg-compensated DL and conventional DL was dominated by thermionic field emission (TFE) and barrier modified TFE, respectively.

DOI： 10.7567/1347-4065/ab65cd

Web of Science

Scopus

Recovery of quantum efficiency on Cs/O-activated GaN and GaAs photocathodes by thermal annealing in vacuum

Daiki Sato, Tomohiro Nishitani, Yoshio Honda, Hiroshi Amano

Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics 38 巻 ( 1 ) 頁： 012603 2020年1月

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

Yang, X; Nitta, S; Pristovsek, M; Liu, YH; Liao, YQ; Kushimoto, M; Honda, Y; Amano, H

2D MATERIALS 7 巻 ( 1 ) 頁： 015004 2020年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：2D Materials

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 || [0 0 0 1]AlN and [1 0 -1 0]h-BN || [1 1 -2 0]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

Web of Science

Scopus

Analysis of trimethylgallium decomposition by high-resolution mass spectrometry

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

Japanese Journal of Applied Physics 59 巻 ( 2 ) 頁： 025511 2020年

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

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

Semiconductor Science and Technology 35 巻 ( 3 ) 頁： 035004 2020年

Preface - JSS Focus Issue on Recent Advances in Wide Bandgap III-Nitride Devices and Solid State Lighting: A Tribute to Isamu Akasaki

Ren F., Mishra K.C., Amano H., Collins J., Han J., Im W.B., Kneissl M., Seong T.Y., Setlur A., Suski T., Zych E.

ECS Journal of Solid State Science and Technology 9 巻 ( 1 ) 頁： 010001 2020年

Damage-Free Plasma Etching to Enhance Performance of AlGaInP-Based Micro-Light Emitting Diode

Lee, SY; Lee, ED; Moon, JH; Choi, B; Oh, JT; Jeong, HH; Seong, TY; Amano, H

IEEE PHOTONICS TECHNOLOGY LETTERS 32 巻 ( 17 ) 頁： 1041 - 1044 2020年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Photonics Technology Letters

We investigated the effect of plasma-etching on the electrical and optical performance of lateral AlGaInP-based red micro-LEDs as a function of etching time, where plasma-etched Ag particles were used as masks. For the sample etched for 12 s, around 33% of the sample surface were randomly etched, whereas for the sample etched for 24 s, nearly 60% were randomly etched with additional nanoscale hillocks. Regardless of etching times, all samples exhibited similar forward voltages of 1.944-1.929 V at $20~\mu \text{A}$ and reverse leakage currents of $1\times 10^{-8}$ A at -10 V. The micro-LEDs fabricated with 12 s-etched and 24 s-etched $p$ -GaP gave 26.2% and 42.3% higher light output powers at $20~\mu \text{A}$ , respectively, than the one with unetched $p$ -GaP. The $S$ parameter decreased with increasing forward current and etching time. The electroluminescence (EL) peak intensities of the micro-LEDs were consistent with their light output performance and included shoulder peaks at 612 nm. Emission images showed that the micro-LEDs with the 24 s-etched $p$ -GaP revealed the most intense and uniform emission area among the three samples.

DOI： 10.1109/LPT.2020.3010820

Web of Science

Scopus

マクロステップを持つ<i>c</i>面AlN/サファイアテンプレート上に成長させたAlGaN量子井戸の物性評価

小島一信, 長澤陽祐, 平野光, 一本松正道, 杉江隆一, 本田善央, 天野浩, 赤﨑勇, 秩父重英

日本結晶成長学会誌 47 巻 ( 3 ) 頁： n/a 2020年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：日本結晶成長学会

<p> The microscopic structural and optical characteristics of AlGaN light-emitting diodes (LEDs) fabricated on the AlN templates with dense macrosteps are shown to clarify the origin of their high internal quantum efficiency of radiation (IQE). The cross-sectional transmission electron microscopy observations under the high-angle annular dark field scanning mode and microscopic energy dispersive X-ray spectroscopy revealed that the AlGaN cladding layer under the AlGaN quantum well (QW) layer had a microscopic compositional modulation, which originates from the macrosteps at the AlN template surface. Moreover, Ga-rich portions in the cladding layer behaved as current micropaths, and the micropaths are connected with the carrier localization structure formed in QWs. The in-plane cathodoluminescence (CL) spectroscopy showed a significant inhomogeneity of the CL characteristics. The gentle slopes at the sample surface showed brighter emissions with a lower peak photon energy, confirming the carrier localization. This carrier localization structure in the QWs combined with the current micropaths in the cladding layer can increase the IQE as well as external quantum efficiency of the AlGaN LEDs.</p>

DOI： 10.19009/jjacg.47-3-04

CiNii Research

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

Liao, YQ; Chen, T; Wang, J; Ando, Y; Yang, X; Watanabe, H; Hirotani, J; Kushimoto, M; Deki, M; Tanaka, A; Nitta, S; Honda, Y; Chen, KJ; Amano, H

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

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Proceedings of the International Symposium on Power Semiconductor Devices and ICs

In this work, gallium nitride (GaN) nanowire (NW) Schottky barrier diodes was fabricated using well-optimized top-down approach. As-fabricated $100 \times 800$-nm-diameter NWs SBD with high current density over 1kA/cm2 at a forward bias of 2.2V, a low differential specific ON-resistance of $0.15\mathrm{m} \Omega \cdot cm^{2}$ are demonstrated. By the virtue of dielectric Reduced Surface Field (RESURF) effect, the device also delivers a breakdown voltage of 515V, leading to a competitive Baliga's Figure of merit of 1.76 GW/cm2.

DOI： 10.1109/ispsd46842.2020.9170101

Web of Science

Scopus

Role of defects in the mid-term degradation of UV-B LEDs investigated by optical and DLTS measurements

Piva F., De Santi C., Deki M., Kushimoto M., Amano H., Tomozawa H., Shibata N., Meneghesso G., Zanoni E., Meneghini M.

GALLIUM NITRIDE MATERIALS AND DEVICES XV 11280 巻頁： 1128015 2020年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering

AlGaN-based UltraViolet Light Emitting Diodes (UV LEDs) are promising devices for replacing the conventional UV lamps, which contain toxic substances like mercury, in order to have smaller devices, lower operating voltage and the possibility of tuning the emission wavelength by changing the Al and Ga content in the alloy. However, UV-LEDs may suffer from a relatively fast degradation of electrical and optical characteristics, that can be due to the generation of defects that increase the Shockley-Read-Hall (SRH) recombination components. The aim of this paper is to study the behavior of UV-B LEDs submitted to a constant current stress, through electrical, optical and spectral characterization, and capacitance deep-level transient spectroscopy (C-DLTS). The results of this analysis demonstrate that UV-B LEDs show a decrease in the driving voltage, probably correlated with the increased activation of the Mg dopant, and an increase in subthreshold forward current, ascribed to the generation of mid-gap defects caused by the stress. We also found a strong optical degradation at low current levels, that indicates the increase in SRH recombination, probably due to the increased density of mid-gap defects. To investigate on the origin of the defects, we carried out C-DLTS measurements; the results indicate the presence of Mg-related defects and/or intrinsic defects related to the GaN growth. Moreover, after stress we notice the appearance of a peak that is strictly related to the increase of mid-gap defects generated during the stress.

DOI： 10.1117/12.2544704

Web of Science

Scopus

Low leakage Mg-compensated GaN Schottky diodes on free-standing GaN substrate for high energy α-particle detection

Sandupatia, A; Arulkurnaran, S; Ranjan, K; Ng, GI; Murumu, PP; Kennedy, J; Deki, M; Nitta, S; Honda, Y; Amano, H

2020 IEEE ELECTRON DEVICES TECHNOLOGY AND MANUFACTURING CONFERENCE (EDTM 2020) 2020年

GaN基板向けレーザスライシング技術の開発

河口大祐, 田中敦之, 油井俊樹, 伊ヶ崎泰則, 和仁陽太郎, 天野浩

年次大会 2020 巻 ( 0 ) 頁： S16306 2020年

高品質AlN 基板上UV-C レーザーダイオード

笹岡千秋, 天野浩

レーザー研究 48 巻 ( 8 ) 頁： 427 2020年

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