Article
Chemistry, Physical
Zahra Azimi, Aswani Gopakumar, Amira S. Ameruddin, Li Li, Thien Truong, Hieu T. Nguyen, Hark Hoe Tan, Chennupati Jagadish, Jennifer Wong-Leung
Summary: Catalyst-free InGaAs nanowires grown by selective area epitaxy show promising potential for future optoelectronic devices in the infrared spectral region. The composition, microstructure, and optical properties of the nanowires are influenced by growth parameters and pattern geometry, with Ga content increasing with certain growth conditions. Understanding these factors can facilitate the engineering of nanowires for optoelectronic applications.
Article
Nanoscience & Nanotechnology
Florian Pantle, Simon Woerle, Monika Karlinger, Felix Rauh, Max Kraut, Martin Stutzmann
Summary: Nanostructures, such as GaN nanofins, are sensitive to their ambient conditions due to their large surface-to-volume ratio. This article presents a systematic study on the environmental sensitivity of the electrical conductivity of GaN nanofins and identifies oxygen and water as responsible for reducing the electrical current through GaN nanofins. The results also reveal the complexity of water adsorption on GaN surfaces and the importance of reproducible pre-treatment and surface passivation.
Article
Physics, Applied
T. Hamachi, T. Tohei, Y. Hayashi, M. Imanishi, S. Usami, Y. Mori, N. Ikarashi, A. Sakai
Summary: The study investigated the propagation behavior of threading dislocations (TDs) in Na-flux-grown GaN and commercially available HVPE-grown GaN, revealing a correlation between TD morphology and Burgers vectors. Unique TDs with specific Burgers vectors were observed using advanced electron diffraction techniques. The inclinations of TDs were affected by the crystal structure, leading to different morphologies in different types of HVPE-grown GaN crystals.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Min Joo Ahn, Kyu-yeon Shim, Woo Seop Jeong, Seongho Kang, Hwayoung Kim, Dae-sik Kim, Junggeun Jhin, Jaekyun Kim, Dongjin Byun
Summary: In this study, a polished plateau-patterned sapphire substrate (PP-PSS) was developed for the epitaxial growth of stress-free GaN microrods. By adjusting the polishing time, selective growth of GaN microrods was achieved on the plateau region of the substrate. The growth mechanism and crystal structure of the GaN microrods were characterized, confirming the feasibility of stress-free epitaxial growth on PP-PSS.
Article
Crystallography
Marzieh Bakhtiary-Noodeh, Theeradetch Detchprohm, Russell D. Dupuis
Summary: This study aims to investigate the unintentional impurity incorporation in GaN epitaxial layers and optimize the growth conditions to reduce background impurity concentrations. The results show that the unintentional incorporation of carbon and silicon impurities is highly dependent on the growth parameters. The use of TEG precursor can reduce the carbon concentration, while the lowest concentration can be achieved with TMG precursor under optimized conditions. Similarly, the lowest background silicon concentration can be achieved with TMG precursor under specific conditions.
JOURNAL OF CRYSTAL GROWTH
(2023)
Article
Chemistry, Multidisciplinary
Vladimir G. Dubrovskii, Simon Escobar Steinvall, Virginie de Mestral, Rajrupa Paul, Jean-Baptiste Leran, Mahdi Zamani, Elias Z. Stutz, Anna Fontcuberta Morral
Summary: Selective area growth of Zn3P2 on InP provides high-quality semiconductor nanostructures made of earth-abundant elements. In the precoalescence stage, Zn3P2 emerges in the form of nanoislands and undergoes a shape transformation. The results are presented in dimensionless variables, allowing simultaneous understanding of islands grown in differently sized pinholes and for different growth times.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Chemistry, Physical
Sonachand Adhikari, Felipe Kremer, Mykhaylo Lysevych, Chennupati Jagadish, Hark Hoe Tan
Summary: GaN/AlGaN core-shell nanowires with various Al compositions have been grown on GaN nanowire array. The AlGaN shells have lower Al compositions than the gas phase input ratio. Defect-related luminescence has been observed in the AlGaN shells, with partial dislocations as the dominant defects. Growth of nonpolar m-plane AlxGa1-xN/AlyGa1-yN quantum wells on the sidewalls of the GaN nanowires shows excellent morphology and optical emission.
NANOSCALE HORIZONS
(2023)
Article
Chemistry, Multidisciplinary
Santhanu Panikar Ramanandan, Petar Tomic, Nicholas Paul Morgan, Andrea Giunto, Alok Rudra, Klaus Ensslin, Thomas Ihn, Anna Fontcuberta i Morral
Summary: We successfully obtained a germanium nanowire network by selectively growing on nanopatterned slits in a metalorganic vapor phase epitaxy system. Measurements on the nanowire devices showed high hole doping and short mean free path, while revealing quantum transport phenomena and spin-orbit length.
Article
Nanoscience & Nanotechnology
A. Filatova-Zalewska, Z. Litwicki, K. Moszak, W. Olszewski, K. Opolczynska, D. Pucicki, J. Serafinczuk, D. Hommel, A. Jezowski
Summary: High thermal conductivity is crucial for nitride-based power electronic and deep-UV light emitters. In this study, in-plane and cross-plane thermal conductivity of AlGaN/GaN superlattices were measured, showing differences in thermal behavior with changing period thickness and temperature. The Callaway method was used for thermal conductivity calculation, taking into account the dependence of boundary scattering rate on phonon wavelength.
Article
Crystallography
Alice Hospodkova, Frantisek Hajek, Tomas Hubacek, Zuzana Gedeonova, Pavel Hubik, Jirf J. Mares, Jirf Pangrac, Filip Dominec, Karla Kuldova, Eduard Hulicius
Summary: Although various aspects of GaN high electron mobility transistor (HEMT) structure have been extensively studied, such as buffer layer architecture, AlGaN barrier, surface passivation, and dielectric choice, little attention has been given to optimize the GaN channel technology. In this work, we demonstrate that by optimizing the channel technology, electron mobility can be significantly improved. We investigated the influence of technological parameters on the transport properties of a series of GaN layers mimicking a HEMT channel. We focused on the layer growth using TEG precursor and examined parameters such as reactor atmosphere, growth temperature, growth rate influenced by precursor concentration, and reactor pressure. By using optimized growth parameters for the HEMT structure, we successfully increased the electron mobility in 2DEG by 30%.
JOURNAL OF CRYSTAL GROWTH
(2023)
Article
Crystallography
Yun Lai, Ding Wang, Qinhao Kong, Xiaoju Luo, Jinfeng Tang, Rensuo Liu, Fei Hou, Xianying Wang, Troy J. Baker
Summary: Four-inch semi-insulating free-standing gallium nitride (GaN) wafers grown by hydride vapor phase epitaxy (HVPE) with carbon doping were obtained through a self-separated process. The as-grown wafer thickness can reach 900 mu m without cracks, and x-ray diffraction rocking curves show low FWHMs. The measured resistivity was greater than 10(10) Omega-cm.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Chemistry, Multidisciplinary
Hua-Chiang Wen, Ssu-Kuan Wu, Cheng-Wei Liu, Jin-Ji Dai, Wu-Ching Chou
Summary: The nanotribological properties of AlxGa1-xN epitaxial films grown on low-temperature-grown GaN/AlN/Si substrates were investigated. It was found that the Al compositions played a crucial role in determining the strength of bonding forces and shear resistance. The measured friction coefficient (mu) values decreased with increasing Al compositions, indicating a transition from brittleness to ductility in the AlxGa1-xN system.
Article
Physics, Applied
Kazuki Ohnishi, Seiya Kawasaki, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Yoshio Honda, Hiroshi Amano
Summary: A vertical GaN p(+)-n junction diode with an ideal breakdown voltage was successfully grown by halide vapor phase epitaxy (HVPE). The steep p(+)-n interface was observed and no Si-accumulating layer was formed due to continuous growth. This method offers improved electrical properties compared to regrowth of p-type GaN layers, with a minimum ideality factor of approximately 1.6.
APPLIED PHYSICS LETTERS
(2021)
Article
Optics
Yaying Liu, Zhaojun Liu, Kei may Lau
Summary: This study presents an all-GaN-based mu LED display with monolithic integrated HEMT and mu LED pixels using the selective area regrowth method. The optimized regrowth pattern improves the crystal quality of regrown mu LED, resulting in high light output power and peak EQE for the mu LED-HEMT. TMAH treatment and Al2O3 surface passivation are performed to minimize nonradiative recombination caused by dry etching damage. Images of HKUST are successfully shown on the customized mu LED-HEMT display board.
Article
Physics, Applied
Caroline E. Reilly, Nirupam Hatui, Thomas E. Mates, Shuji Nakamura, Steven P. DenBaars, Stacia Keller
Summary: This research explores the growth of AlN at temperatures below 550 degrees C via MOCVD using a flow-modulated epitaxy scheme, investigating the morphological, compositional, and electronic properties of the films. The study reveals high sheet charges and mobilities for two dimensional electron gases formed at the interface between the low temperature grown AlN layers and the high temperature deposited semi-insulating GaN base layers. Despite low growth temperatures, unintentional gallium incorporation is observed in nominally pure AlN barrier layers near the GaN interface. These results pave the way for the integration of nitride-based electronics on temperature sensitive substrates via epitaxy-based schemes.
APPLIED PHYSICS LETTERS
(2021)
Editorial Material
Physics, Applied
Takashi Itoh, Shigeya Naritsuka, Yasufumi Fujiwara, Mineo Hiramatsu, Makoto Kasu, Kazunori Koga, Hiroki Kondo, Koh Matsumoto, Osamu Nakatsuka, Kiichi Niitsu, Tomohiro Nozaki, Takayuki Ohta, Osamu Sakai, Hideki Sato, Tetsuya Takeuchi, Giichiro Uchida
JAPANESE JOURNAL OF APPLIED PHYSICS
(2017)
Review
Physics, Applied
Makoto Kasu
JAPANESE JOURNAL OF APPLIED PHYSICS
(2017)
Article
Materials Science, Multidisciplinary
A. Boussadi, A. Tallaire, M. Kasu, J. Barjon, J. Achard
DIAMOND AND RELATED MATERIALS
(2018)
Article
Materials Science, Multidisciplinary
Satoshi Masuya, Makoto Kasu
DIAMOND AND RELATED MATERIALS
(2018)
Article
Materials Science, Multidisciplinary
Niloy Chandra Saha, Makoto Kasu
DIAMOND AND RELATED MATERIALS
(2019)
Article
Materials Science, Multidisciplinary
Niloy Chandra Saha, Makoto Kasu
DIAMOND AND RELATED MATERIALS
(2019)
Article
Materials Science, Multidisciplinary
Jianbo Liang, Yan Zhou, Satoshi Masuya, Filip Gucmann, Manikant Singh, James Pomeroy, Seongwoo Kim, Martin Kuball, Makoto Kasu, Naoteru Shigekawa
DIAMOND AND RELATED MATERIALS
(2019)
Article
Physics, Applied
Ritsuko Sato, Yasuo Chiba, Masayuki Chikamatsu, Yuji Yoshida, Tetsuya Taima, Makoto Kasu, Atsushi Masuda
JAPANESE JOURNAL OF APPLIED PHYSICS
(2019)
Article
Physics, Applied
Ritsuko Sato, Yasuo Chiba, Masayuki Chikamatsu, Yuji Yoshida, Tetsuya Taima, Makoto Kasu, Atsushi Masuda
JAPANESE JOURNAL OF APPLIED PHYSICS
(2020)
Article
Physics, Applied
Ritsuko Sato, Tetsuyuki Ishii, Sungwoo Choi, Yasuo Chiba, Makoto Kasu, Atsushi Masuda
JAPANESE JOURNAL OF APPLIED PHYSICS
(2019)
Article
Physics, Applied
Niloy Chandra Saha, Kazutoshi Takahashi, Masaki Imamura, Makoto Kasu
JOURNAL OF APPLIED PHYSICS
(2020)
Article
Physics, Applied
Tamotsu Okamoto, Tomoya Igari, Takahiro Fukui, Ryuto Tozawa, Yasuhito Gotoh, Nobuhiro Sato, Yasuki Okuno, Tomohiro Kobayashi, Mitsuru Imaizumi, Masafumi Akiyoshi
Summary: In this study, a compact and radiation-tolerant radiation dosimeter without bias voltage application using CdTe solar cells was proposed for severe radiation environment near a nuclear reactor pressure vessel. The CdTe solar cells showed sufficient tolerance against gamma-ray exposure up to 3 MGy and linearly increased current density with increasing gamma-ray intensity. By stacking and parallel connecting CdTe solar cells, gamma-ray sensitivity was successfully improved, enabling high responsivity and low noise detection even under high flux neutron environments.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Jianbo Liang, Ayaka Kobayashi, Yasuo Shimizu, Yutaka Ohno, Seong-Woo Kim, Koji Koyama, Makoto Kasu, Yasuyoshi Nagai, Naoteru Shigekawa
Summary: The direct integration of GaN and diamond for high-power devices faces challenges due to mismatch in lattice and thermal-expansion coefficients. A successful fabrication of GaN/diamond heterointerface was achieved using a surface activated bonding method at room temperature. An intermediate layer composed of amorphous carbon and diamond is formed at the interface, with Ga and N atoms diffusing during the bonding process and transitioning to diamond after annealing.
ADVANCED MATERIALS
(2021)
Article
Physics, Applied
Sayleap Sdoeung, Kohei Sasaki, Katsumi Kawasaki, Jun Hirabayashi, Akito Kuramata, Makoto Kasu
Summary: The surface defects induced by probe attachment play a crucial role in causing reverse leakage current in β-Ga2O3 SBDs, which is essential for the commercialization of power devices.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Takayoshi Oshima, Yuji Kato, Masaya Oda, Toshimi Hitora, Makoto Kasu
APPLIED PHYSICS EXPRESS
(2017)
