Article
Physics, Applied
Masahiro Horita, Tetsuo Narita, Tetsu Kachi, Jun Suda
Summary: In this study, energy levels due to intrinsic point defects in n-type GaN layers were investigated using DLTS. Two electron traps, EE1 and EE2, were observed, corresponding to nitrogen vacancies and nitrogen interstitials. Annealing led to a reduction in the trap densities at the same rate, indicating the migration of nitrogen interstitials and subsequent recombination with nitrogen vacancies.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Abdulraoof I. A. Ali, Helga T. Danga, Jacqueline M. Nel, Walter E. Meyer
Summary: This study investigated the growth of GaN using electrochemical deposition on different substrates and found that the properties of the film were influenced by both the substrate type and deposition conditions. X-ray diffraction analysis revealed a mixture of hexagonal and cubic structures in the film, with crystallite sizes ranging from 11 nm to 18 nm. Schottky diodes fabricated on the thin films demonstrated specific electrical characteristics, including barrier height and carrier density, which changed after irradiation with alpha particles.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Physics, Applied
Meguru Endo, Masahiro Horita, Jun Suda
Summary: This study investigated deep levels in p-type GaN grown via metalorganic vapor-phase epitaxy using deep level transient spectroscopy. The results showed that after exposure to an electron beam, a peak due to EHa hole traps was observed in the spectra. Applying a forward bias generated signals for EHb and EHc hole traps while weakening the EHa signal and increasing the net accepter concentration. The generation of these traps may be related to V-N or N-I defects and complex defects.
APPLIED PHYSICS LETTERS
(2022)
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
Engineering, Electrical & Electronic
J. Plesiewicz, P. Kruszewski, V. P. Markevich, P. Prystawko, S. Bulka, M. Hallsal, I. Crowe, L. Sun, A. R. Peaker
Summary: The results of junction spectroscopy measurements on deep-level defects in MOVPE n-GaN samples subjected to 1.5 MeV electron irradiation are compared with published results for epi-GaN materials grown by other techniques. Two new electron traps, EE1 and EE2, are introduced by 1.5-MeV electron irradiation, with electronic levels at about 0.14 and 0.98 eV below the conduction band edge. The EE1 trap exhibits a strong electric field dependence and its activation energy can be lowered by a strong electric field. The complexity of the EE1 trap level structure is revealed through DLTS measurements.
MICROELECTRONIC ENGINEERING
(2023)
Article
Nanoscience & Nanotechnology
Larionette P. L. Mawlong, Anh Tuan Hoang, Jyothi Chintalapalli, Seunghyeon Ji, Kihyun Lee, Kwanpyo Kim, Jong-Hyun Ahn
Summary: This study introduces a new method for synthesizing large-area, high-quality two-dimensional transition metal dichalcogenides, such as MoS2. The method improves the performance of photodetectors and reduces sulfur vacancy defects in the film, which significantly affects material quality.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Physics, Applied
S. Xu, S. Zhang, J. D. Kirch, S. Suri, N. Pokharel, H. Gao, H. Kim, P. Dhingra, M. L. Lee, D. Botez, L. J. Mawst
Summary: Room-temperature, pulsed-operation lasing of 8.5 μm-emitting InP-based quantum cascade lasers (QCLs) with low threshold-current density and watt-level output power is demonstrated on (001) GaAs substrates grown by metal-organic chemical vapor deposition. The use of nearly fully relaxed InP buffer with strained InAs quantum-dot-like dislocation-filter layers resulted in a smooth terminal buffer-layer surface with low roughness and mid-range threading-dislocation density. High-performance InP-based QCLs emitting near 8 μm can be achieved on lattice-mismatched substrates.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Ceramics
Bin Li, Qiankun Ju, Wenting Hong, Qian Cai, Jinxin Lin, Wei Liu
Summary: The study successfully synthesized a novel molybdenum disulfide using chemical vapor deposition, with the synthesis reaction being carried out in an inert gas environment. The use of a high concentration of molybdenum precursor helped control the morphology of molybdenum disulfide, leading to the innovative method for synthesizing bilayer molybdenum disulfide.
CERAMICS INTERNATIONAL
(2021)
Article
Chemistry, Multidisciplinary
Xiang Xu, Tingting Zhong, Nian Zuo, Zexin Li, Dongyan Li, Lejing Pi, Ping Chen, Menghao Wu, Tianyou Zhai, Xing Zhou
Summary: In this study, CuCrS2 nanoflakes were successfully synthesized by salt-assisted chemical vapor deposition, demonstrating switchable ferroelectric polarization even at a thickness of 6 nm. The high T-C of around 700 K can be attributed to the robust tetrahedral bonding configurations of Cu cations, with further clarification provided by a theoretically predicted high order-disorder transition barrier and structure evolution from 600 to 800 K. Additionally, interlocked out-of-plane and in-plane ferroelectric domains were observed, leading to the demonstration of two devices based on different polarizations.
Review
Chemistry, Multidisciplinary
Jinhong Du, Bo Tong, Shuangdeng Yuan, Nian Dai, Rui Liu, Dingdong Zhang, Hui-Ming Cheng, Wencai Ren
Summary: This article reviews the recent advances and significant development of CVD-grown graphene towards flexible optoelectronics. The challenges of improving optoelectronic properties, tuning work functions, and controlling interfaces are discussed, and the importance of fabricating large-area devices on flexible substrates is emphasized.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Physics, Applied
Jiadong Yu, Zixuan Zhang, Yi Luo, Jian Wang, Lai Wang, Xiang Li, Zhibiao Hao, Changzheng Sun, Yanjun Han, Bing Xiong, Hongtao Li
Summary: This study reports the fabrication of high-quality gallium nitride (GaN) films using the ICP-MOCVD method at a low temperature. The GaN films were then used to produce thin-film transistors and photodetectors. The results show that these films exhibit excellent performance, demonstrating their potential for electronic device fabrication.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Julien Bassaler, Remi Comyn, Catherine Bougerol, Yvon Cordier, Farid Medjdoub, Philippe Ferrandis
Summary: This study focuses on the material investigation of an Al0.9Ga0.1N/GaN heterostructure, identifying various defects in the GaN channel that may contribute to reduced mobility and are linked to the quality of the channel interfaces.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Weiqu Chen, Zimin Chen, Zeqi Li, Zeyuan Fei, Yanli Pei, Gang Wang, Zhiyuan He
Summary: High quality epsilon-phase gallium oxide (Ga2O3) thin films have been successfully grown on silicon substrates using metal-organic chemical vapor deposition (MOCVD). The growth pressure is found to be an important parameter that affects the thin film quality.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Multidisciplinary
Xiao Wang, Yu-Min Zhang, Yu Xu, Zhi-Wei Si, Ke Xu, Jian-Feng Wang, Bing Cao
Summary: In this study, a large-area freestanding GaN layer was successfully separated from a specific structure of Fe-doped GaN substrate through an electrochemical liftoff process, simplifying the preparation process and potentially reducing costs.
Article
Multidisciplinary Sciences
Sergey G. Menabde, In-Ho Lee, Sanghyub Lee, Heonhak Ha, Jacob T. Heiden, Daehan Yoo, Teun-Teun Kim, Tony Low, Young Hee Lee, Sang-Hyun Oh, Min Seok Jang
Summary: The acoustic plasmon mode in a graphene-dielectric-metal structure shows strong light-matter interaction with relatively small propagation loss, allowing for real-space mapping under ambient conditions.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Applied
Shohei Nakamura, Atsushi Tanide, Takahiro Kimura, Soichi Nadahara, Kenji Ishikawa, Osamu Oda, Masaru Hori
Summary: This study demonstrates damage-free atomic layer etching (ALE) of GaN using a cyclic process, where the chlorinated layer formed by Cl2 plasma exposure is removed by Ar plasma. A substrate temperature of 400 degrees C promotes etching even at lower ion energy, resulting in a higher ALE synergy of 62%. The proposed high temperature ALE method shows promise for achieving damage-free etching of GaN.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Swapnil Ghodke, Motoyuki Murashima, Dennis Christy, Ngo Van Nong, Kenji Ishikawa, Osamu Oda, Noritsugu Umehara, Masaru Hori
Summary: The mechanical properties, including compressive strength and modulus, of the maze-like CNW structure synthesized by RI-PECVD technique were analyzed using nanoindentation method, revealing an elastoplastic behavior.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Electrical & Electronic
Phuc Duc Nguyen, Yoshifumi Shiraki, Kenji Ishikawa, Jun Muramatsu, Noboru Harada, Takehiro Moriya
Summary: We propose a two-level dimmer based on binary distribution matching for region-of-interest (RoI) signaling applications. Our extended multiset-partition distribution matching (EMPDM) algorithm with a novel binary-tree-structure implementation reduces the rate loss of the dimmer. Additionally, we introduce 4p-EMPDM, a compact version of EMPDM, which guarantees flicker mitigation for visible-light RoI signaling systems without using any run-length limited code.
IEEE PHOTONICS JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Ryusei Sakai, Hiroki Kondo, Kenji Ishikawa, Takayuki Ohta, Mineo Hiramatsu, Hiromasa Tanaka, Masaru Hori
Summary: Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) was performed using carbon nanowalls (CNWs) grown with the addition of oxygen in a mixture of CH4 and H2 gases. The high-quality CNWs had different crystallinity and C-OH groups compared to normal CNWs, but similar wall-to-wall distances and wettability. At a low laser fluence, the high-quality CNWs showed improved sensitivity for the detection of low-molecular-weight analytes while maintaining a high survival yield (SY) of 0.89.
Editorial Material
Physics, Multidisciplinary
Pankaj Attri, Kazunori Koga, Hirofumi Kurita, Kenji Ishikawa, Masaharu Shiratani
FRONTIERS IN PHYSICS
(2023)
Article
Biochemistry & Molecular Biology
Camelia Miron, Kenji Ishikawa, Satoshi Kashiwagura, Yuki Suda, Hiromasa Tanaka, Kae Nakamura, Hiroaki Kajiyama, Shinya Toyokuni, Masaaki Mizuno, Masaru Hori
Summary: Cold atmospheric pressure plasmas have the potential to be effective medical tools for cancer treatment. However, the understanding of the role of reactive species formed in plasma and their activation of biochemical pathways is still limited. In this study, we investigated the generation of chemical compounds in Ringer's acetate solution using low-temperature plasma and their effects on breast cancer cells and non-tumorigenic breast epithelial cells. The results showed that the plasma-derived compounds had both stimulatory and inhibitory effects on cell viability, depending on their concentration in the irradiated liquids.
FREE RADICAL RESEARCH
(2023)
Article
Physics, Applied
Shinji Yoshimura, Yoko Otsubo, Akira Yamashita, Katsuki Johzuka, Takayoshi Tsutsumi, Kenji Ishikawa, Masaru Hori
Summary: The characteristics of a gas-temperature-controllable atmospheric-pressure helium plasma jet and the development of an experimental system for cell viability assays of yeasts are described. The physicochemical properties of the plasma plume were similar to those of a typical helium plasma jet and allowed for maintaining a temperature suitable for yeast. The experimental system showed good reproducibility of cell viability and can be used for various experiments, including the identification of genes involved in resistance to direct plasma irradiation.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Yang Liu, Kenji Ishikawa, Hiromasa Tanaka, Camelia Miron, Takashi Kondo, Kae Nakamura, Masaaki Mizuno, Hiroaki Kajiyama, Shinya Toyokuni, Masaru Hori
Summary: Lactate, an important intermediate in the food and pharmaceutical industries, has been found to have effective antitumor action when exposed to plasma in Ringer's solution. This exposure leads to the production of small molecule aldehydes, ketones, and organic acids, as well as the formation of furanone isomers. The compound 2,3-Dimethyl-tartaric acid is believed to be the key component in the antitumor action, and various aqueous reaction mechanisms, including dehydration, esterification, hydrolysis, and dimerization, have been explained. This study has implications for the development of novel cancer therapies and the field of plasma organic chemistry.
PLASMA PROCESSES AND POLYMERS
(2023)
Article
Multidisciplinary Sciences
Deng-Ke Xi, Seong Ling Yap, Nitturi Naresh Kumar, Chian Cheng Toh, Kenji Ishikawa, Masaru Hori
Summary: Plasma assisted priming is effective in improving the germination rate and growth performance of papaya seeds.
Article
Materials Science, Multidisciplinary
Shih-Nan Hsiao, Nikolay Britun, Thi-Thuy-Nga Nguyen, Takayoshi Tsutsumi, Kenji Ishikawa, Makoto Sekine, Masaru Hori
Summary: The effects of substrate temperature on the etch rate and selectivity of PECVD-prepared SiN, SiO2, and a-C films were investigated. The etch rate of SiN was higher than that of SiO2 at all temperatures, and decreased as the temperature decreased. The etch rate of SiO2, on the other hand, increased with decreasing temperature. The selectivity of SiN over SiO2 reached unity at -20°C. The etch rate of a-C films remained constant regardless of temperature. The difference in FC thickness between SiN and SiO2 films accounted for the lower etch rate of SiO2, and the decrease in FC thickness at lower temperatures led to a decrease in etch rate. The higher stability of the surface N-H modification layer at low temperatures explained the decrease in etch rate for SiN etching, as confirmed by in situ FTIR.
Article
Multidisciplinary Sciences
Hiromasa Tanaka, Daijiro Iwata, Yuki Shibata, Tetsunari Hase, Daisuke Onoshima, Naoyuki Yogo, Hirofumi Shibata, Mitsuo Sato, Kenji Ishikawa, Ikuo Nagasawa, Yoshinori Hasegawa, Makoto Ishii, Yoshinobu Baba, Masaru Hori
Summary: Various liquid biopsy methods have been developed for non-invasive and early disease detection. Researchers have developed a glass filter that can capture circulating tumor cells (CTCs) and used it for detecting CTCs in lung cancer patients. They also developed a visualization system and demonstrated the direct culture of captured cells on the glass filter.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Applied
Ma. Shanlene D. C. Dela Vega, Thi-Thuy-Nga Nguyen, Hiroki Kondo, Takayoshi Tsutsumi, Kenji Ishikawa, Masaru Hori
Summary: This work explores the application of the in-liquid plasma (ILP) process for carbon formation on ethanol-immersed metal substrates. Graphene, graphitic carbon, and amorphous carbon were produced simultaneously during plasma discharge. Graphitic and amorphous carbon coexisted on the metal substrate surface, while free-standing graphene formed in ethanol. The proposed mechanism for carbon formation on metal substrates is presented.
PLASMA PROCESSES AND POLYMERS
(2023)
Review
Biochemistry & Molecular Biology
Kenji Ishikawa, Keigo Takeda, Shinji Yoshimura, Takashi Kondo, Hiromasa Tanaka, Shinya Toyokuni, Kae Nakamura, Hiroaki Kajiyama, Masaaki Mizuno, Masaru Hori
Summary: This review provides a historical background of the development of biological applications of low-temperature plasmas. It assesses the generation of plasma, methods and devices, plasma sources, and measurements of plasma properties. Currently, direct irradiation methods and indirect methods using plasma-treated liquids are being increasingly used in preclinical studies and cancer therapy. The authors discuss the prospects for further development in cancer therapeutic applications by understanding the interactions between the plasma and living organisms.
FREE RADICAL RESEARCH
(2023)
Review
Biochemistry & Molecular Biology
Hiromasa Tanaka, Masaaki Mizuno, Kenji Ishikawa, Camelia Miron, Yasumasa Okazaki, Shinya Toyokuni, Kae Nakamura, Hiroaki Kajiyama, Masaru Hori
Summary: Low-temperature plasma (LTP) has been widely used in life science. LTP can be used to irradiate water, medium, and Ringer's solutions to produce plasma-activated solutions, which contain chemical compounds produced by reactions among LTP, air, and solutions. Reactive oxygen and nitrogen species (RONS) are major components in plasma-activated solutions, and recent studies have shown the production of plasma-activated organic compounds in plasma-activated Ringer's lactate solution (PAL). In vitro and in vivo studies have demonstrated the anti-tumor effects of PAL on cancers, and biochemical analyses have revealed the intracellular molecular mechanisms of cancer cell death by PAL.
FREE RADICAL RESEARCH
(2023)
Article
Chemistry, Analytical
Daisuke Onoshima, Tetsunari Hase, Naoto Kihara, Daiki Kuboyama, Hiromasa Tanaka, Naoya Ozawa, Hiroshi Yukawa, Mitsuo Sato, Kenji Ishikawa, Yoshinori Hasegawa, Makoto Ishii, Masaru Hori, Yoshinobu Baba
Summary: This study reports the use of a blood microfiltration device for noninvasive detection of circulating tumor cells (CTCs). The method efficiently separates and captures CTCs from whole blood, allowing for genomic profiling to evaluate tumor characteristics and treatment efficacy.
ACS MEASUREMENT SCIENCE AU
(2023)