研究者詳細 - 天野　浩

論文 - 天野　浩

分割表示 827 件中 141 - 160 件目／全件表示 >>

Design and characterization of a low-optical-loss UV-C laser diode

Zhang Z., Kushimoto M., Sakai T., Sugiyama N., Schowalter L.J., Sasaoka C., Amano H.

Japanese Journal of Applied Physics 59 巻 ( 9 ) 2020年9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：Japanese Journal of Applied Physics

We present an optical modeling and characterization study of prototype ultraviolet laser diode (LD) structures grown on single-crystal AlN substrates, with focus on the reduction of modal loss caused by optical mode coupling to the absorptive layers on the p-side (i.e. p-contact and p-metal layers). The transparent AlN substrates enabled optical pumping for measuring modal loss without requiring functioning LDs. The modal loss measured in this way was in good agreement with electrically evaluated results of processed LDs, and both results were consistent with optical modeling predictions. By using 0.32 μm thick p-side cladding, we were able to suppress the modal loss of the designed LD structure to 8.4 cm-1, where the contribution from the absorptive p-contact layers was less than 3 cm-1.

DOI： 10.35848/1347-4065/abaac6

Scopus

Design and characterization of a low-optical-loss UV-C laser diode

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

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( 9 ) 2020年9月

Increasing the Luminescence Efficiency of Long-Wavelength (In,Ga)N Quantum Well Structures by Electric Field Engineering Using an (Al,Ga)N Capping Layer

Vichi Stefano, Robin Yoann, Sanguinetti Stefano, Pristovsek Markus, Amano Hiroshi

PHYSICAL REVIEW APPLIED 14 巻 ( 2 ) 頁： 024018 2020年8月

Thermodynamic analysis of the gas phase reaction of Mg-doped GaN growth by HVPE using MgO

Kimura T., Ohnishi K., Amano Y., Fujimoto N., Araidai M., Nitta S., Honda Y., Amano H., Kangawa Y., Shiraishi K.

Japanese Journal of Applied Physics 59 巻 ( 8 ) 頁： 088001 2020年8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：Japanese Journal of Applied Physics

The halide vapor phase epitaxy (HVPE) of Mg-doped GaN using solid MgO is investigated. Thermodynamic analysis of the reactions amongst MgO, HCl and N2 is performed based on first-principles calculations. It is found that the equilibrium partial pressure of MgCl2 is the highest amongst magnesium related molecules at 900 °C. By increasing the input partial pressure of HCl, the pressure of MgCl2 is increased, which agrees well with recently reported experiments. From these results, it is concluded that MgCl2 is the key molecule which plays the most important role for Mg-doping in fabricating p-type GaN using HVPE with MgO.

DOI： 10.35848/1347-4065/aba0d5

Scopus

Growth of high-quality GaN by halogen-free vapor phase epitaxy

Kimura T., Kataoka K., Uedono A., Amano H., Nakamura D.

Applied Physics Express 13 巻 ( 8 ) 頁： 085509 2020年8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：Applied Physics Express

We report the electrical and optical properties of gallium nitride grown by halogen-free vapor phase epitaxy (HF-VPE). The electron mobility of the HF-VPE-GaN layers was found to be comparable to or better than the GaN layers obtained using MOCVD. The positron annihilation spectroscopy analyses revealed that the density of the electroneutral or negatively charged vacancy-type defects in the HF-VPE-GaN layers was below the detection limit (≤1015 cm-3), equivalent to that of a defect-free hydride vapor phase epitaxy (HVPE)-GaN reference sample. Our study shows that the HF-VPE technique can be employed to achieve high-quality and cost-effective bulk crystal and epitaxial layer growth for GaN devices.

DOI： 10.35848/1882-0786/aba494

Scopus

Thermodynamic analysis of the gas phase reaction of Mg-doped GaN growth by HVPE using MgO

Kimura Tomoya, Ohnishi Kazuki, Amano Yuki, Fujimoto Naoki, Araidai Masaaki, Nitta Shugo, Honda Yoshio, Amano Hiroshi, Kangawa Yoshihiro, Shiraishi Kenji

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( 8 ) 2020年8月

Growth of high-quality GaN by halogen-free vapor phase epitaxy

Kimura Taishi, Kataoka Keita, Uedono Akira, Amano Hiroshi, Nakamura Daisuke

APPLIED PHYSICS EXPRESS 13 巻 ( 8 ) 2020年8月

Pulsed-flow growth of polar, semipolar and nonpolar AlGaN

Dinh, DV; Hu, N; Honda, Y; Amano, H; Pristovsek, M

JOURNAL OF MATERIALS CHEMISTRY C 8 巻 ( 25 ) 頁： 8668 - 8675 2020年7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：Journal of Materials Chemistry C

The impacts of pulsed-flow growth on aluminium incorporation in polar (0001), semipolar (1013) and (1122), as well as nonpolar (1010) AlGaN layers have been investigated. The layers were grown simultaneously on differently oriented AlN/sapphire templates by metal-organic vapour phase epitaxy. The AlN mole fraction (0 < xAlN ≤ 0.85) of the layers was varied by simply changing the supply time of the aluminium precursor while keeping nitrogen and gallium precursors constant. Phase separation has been observed for the (0001) and (1122) layers by X-ray diffraction, and is attributed to their different surface reconstructions during growth. In contrast, no phase separation has been observed for the (1010) and (1013) layers, attributed to their stable surfaces during growth. The AlN mole fraction of the differently oriented layers generally follows the order: (1122) < (0001) < (1013) ≤ (1010), attributed to their different surface dangling-bond densities. By means of room-temperature photoluminescence measurements, high carbon-incorporation has quantitatively been found in all the layers. This journal is

DOI： 10.1039/d0tc01369b

Web of Science

Scopus

Screw dislocation that converts p-type GaN to n-type: Microscopic study on Mg condensation and leakage current in p-n diodes

T. Nakano, Y. Harashima, K. Chokawa, K. Shiraishi, A. Oshiyama, Y. Kangawa, S. Usami, N. Mayama, K. Toda, A. Tanaka, Y. Honda, H. Amano

Applied Physics Letters 117 巻 ( 1 ) 頁： 012105 2020年7月

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

Sandupatla A., Arulkumaran S., Ng G.I., Ranjan K., Deki M., Nitta S., Honda Y., Amano H.

Applied Physics Express 13 巻 ( 7 ) 頁： 074001 2020年7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：Applied Physics Express

Current-voltage-temperature characteristics (0 °C to 150 °C) of SBDs on highly compensated 15 μm and 30 μm n-type GaN drift layer were measured for voltages up to-300 V and up to-800 V, respectively. When the temperature is between 75 °C and 100 °C, both SBDs exhibited a similar change in conduction mechanism from thermionic field emission (TFE) to thermionic emission (TE) due to the activation of N-vacancies (VN) (Ea =-1.67 ± 0.02 eV). However, at high voltages when the temperature is >100 °C, the conduction mechanism changes from TE to TFE due to the de-trapping of electrons from activated carbon-traps (Ea = +0.69 eV) in the grown drift layers.

DOI： 10.35848/1882-0786/ab93a0

Scopus

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

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

APPLIED PHYSICS EXPRESS 13 巻 ( 7 ) 2020年7月

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

Kushimoto, M; Sakai, T; Ueoka, Y; Tomai, S; Katsumata, S; Deki, M; Honda, Y; Amano, H

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 217 巻 ( 14 ) 頁： 1900955 2020年7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：Physica Status Solidi (A) Applications and Materials Science

The properties of phase-separated MgZnO induced by heat treatment are investigated, because the electrical conductivity of MgZnO deposited by sputtering can be improved by heat treatment. The absorption edge shows a red shift, but the transmittance in the ultraviolet (UV)-C region increases after heat treatment. This is due to the formation of wurtzite (WZ) MgZnO with a high Zn content and a rock salt (RS) structure with a low Zn content induced by phase separation. This suggests that the current path is formed by the WZ crystals with low resistivity, and the transmittance in the UV region is increased by the RS crystals with high transmittance. It is confirmed that the RS structure is partially mixed with the WZ crystal in the in-plane direction. In contrast, different distributions of crystals are observed in the stacking direction. A WZ structure is formed after RS-MgZnO is formed on the substrate interface. It is found that Mg is incorporated into the RS structure by heat treatment, and Mg-rich MgZnO is formed.

DOI： 10.1002/pssa.201900955

Web of Science

Scopus

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

Liu Q., Fujimoto N., Shen J., Nitta S., Tanaka A., Honda Y., Sitar Z., Boćkowski M., Kumagai Y., Amano H.

Journal of Crystal Growth 539 巻頁： 125643 2020年6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：Journal of Crystal Growth

Lattice bow generated by 40 µm thick HVPE homoepitaxial layers on commercial free-standing, ammonothermal and HVPE GaN wafers was studied. While a change in lattice bow was measured for all wafers, the additional bow on the ammonothermal GaN wafers was minimal. The main driving force for the observed increase in the lattice bow for HVPE wafers was related to stress in the films generated by the elongation of dislocations via climb and generation of new dislocations at the homoepitaxial interface. Lattice bow is a crucial wafer parameter as it determines the variation of the offcut across the surface. If an offcut variation of 0.1° is allowed for desired control surface morphology, composition of alloys, and uniformity of doping on this surface, the measured bow on the two HVPE GaN wafers and one ammonothermal GaN wafer limits their uniformity-diameter to ~0.5″, 1″ and >4″, respectively.

DOI： 10.1016/j.jcrysgro.2020.125643

Scopus

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

Ohnishi K., Amano Y., Fujimoto N., Nitta S., Honda Y., Amano H.

Applied Physics Express 13 巻 ( 6 ) 頁： 016007 2020年6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：Applied Physics Express

Halide vapor phase epitaxy of p-Type GaN:Mg films was realized by using solid MgO as the Mg source. The Mg concentration was controlled by supplying HCl gas in a MgO source zone. Mg-related photoluminescence peaks were observed at around 3.3 and 2.9 eV. For a sample with a Mg concentration of 2.8 × 1019 cm-3, the Hall-effect measurement showed p-Type conduction with a hole concentration and a hole mobility of 1.3 × 1017 cm-3 and 9.1 cm2 V-1 s-1, respectively, at room temperature. The Mg acceptor level was 232 15 meV, which is in good agreement with the previous report.

DOI： 10.35848/1882-0786/ab9166

Scopus

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

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

APPLIED PHYSICS EXPRESS 13 巻 ( 6 ) 2020年6月

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

Liu, Q; Fujimoto, N; Shen, J; Nitta, S; Tanaka, A; Honda, Y; Sitar, Z; Bockowski, M; Kumagai, Y; Amano, H

JOURNAL OF CRYSTAL GROWTH 539 巻 2020年6月

Oxygen Incorporation Kinetics in Vicinal <i>m</i>(10-10) Gallium Nitride Growth by Metal-Organic Vapor Phase Epitaxy

Yosho, D; Shintaku, F; Inatomi, Y; Kangawa, Y; Iwata, JI; Oshiyama, A; Shiraishi, K; Tanaka, A; Amano, H

PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS 14 巻 ( 6 ) 頁： 2000142 2020年6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：Physica Status Solidi - Rapid Research Letters

The oxygen incorporation kinetics of vicinal m(10−10) gallium nitride (GaN) growth during metal-organic vapor phase epitaxy is clarified using a diffusion equation-based approach that incorporates diffusion potentials obtained by large-scale density functional theory (DFT) calculations. A diffusion model based on the Burton, Cabrera and Frank (BCF) theory is proposed, and then, the oxygen concentration in the epitaxial films is calculated quantitatively. The calculation results agree with the experimental tendency that the oxygen concentration in the −c 5° off m-GaN epilayers is lower than that in the +c 5° off m-GaN epilayers. Then, the off-angle dependence of oxygen incorporation in vicinal m-GaN growth is predicted.

DOI： 10.1002/pssr.202000142

Web of Science

Scopus

Vertical GaN-on-GaN Schottky Diodes as α-Particle Radiation Sensors.

11 巻 ( 5 ) 頁： 519 2020年5月

Improving the Leakage Characteristics and Efficiency of GaN-based Micro-Light-Emitting Diode with Optimized Passivation

Lee, H; Lee, JH; Park, JS; Seong, TY; Amano, H

ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY 9 巻 ( 5 ) 頁： 055001 2020年5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：ECS Journal of Solid State Science and Technology

We investigated the effect of atomic layer deposition (ALD) Al2O3 (50 nm)/plasma-enhanced chemical vapour deposition (PECVD) SiO2 (250 nm) and PECVD SiO2 (300 nm) passivation layers on the leakage current and efficiency of InGaN-based micro-LEDs with different sizes. Regardless of passivation layers, the leakage current increased with decreasing LED size and increasing reverse bias. Emission microscopy examination showed that with increasing reverse bias, the number of defect-related emission spots and their intensities increased. For the micro-LEDs <50 μm, the emission spots were mainly located at the sidewall regions. Above-10 V, the single PECVD SiO2 passivation layer gave higher leakage current than the double ALD-Al2O3/PECVD-SiO2 layer. The micro-LEDs with the single passivation layer gave the ideality factors of about 2.0, while that with the double layer exhibited values smaller than 2.0. The micro-LEDs with the double passivation layer exhibited external quantum efficiency peaks at lower current density compared to those with the single layer. It was shown that smaller micro-LEDs were more sensitively dependent on the types of the passivation layers. These results exhibit that the ALD-Al2O3/PECVD-SiO2 passivation layer is more effective in suppressing the sidewall damage-induced current than the PECVD-SiO2 layer.

DOI： 10.1149/2162-8777/ab915d

Web of Science

Scopus

Impact of high-Temperature implantation of Mg ions into GaN

Takahashi M., Tanaka A., Ando Y., Watanabe H., Deki M., Kushimoto M., Nitta S., Honda Y., Shima K., Kojima K., Chichibu S.F., Amano H.

Japanese Journal of Applied Physics 59 巻 ( 5 ) 頁： 056502 2020年5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：Japanese Journal of Applied Physics

Magnesium (Mg) ion implantation into gallium nitride (GaN) at 1000 °C is proposed. Since ion implantation and annealing occur simultaneously in high-Temperature implantation, it is considered that Mg ions can be introduced at an appropriate position upon their implantation. GaN vertical diodes implanted with Mg ions were fabricated and current-voltage measurements were performed. As a result, clear rectifying properties were confirmed in a sample that was implanted with Mg ions at 1000 °C and annealed after implantation. However, the sample subjected to Mg ion implantation at RT and annealed after implantation showed no clear rectification. These results show that high-Temperature implantation of Mg ions at 1000 °C reduces Mg ion implantation-induced damage and simultaneously activates Mg ions upon their implantation.

DOI： 10.35848/1347-4065/ab8b3d

Scopus

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