Article
Materials Science, Coatings & Films
Thibaut Meyer, Camille Petit-Etienne, Erwine Pargon
Summary: This study provides a comprehensive characterization of the GaN surface after etching in Cl-2 plasma. The etching mechanisms of GaN are shown to be influenced by the chlorine radical density in the plasma, which is in turn affected by the carrier wafer. The choice of carrier wafer and its chemical reactivity with Cl-2 plasma can significantly impact the GaN etch rates and surface contamination.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2022)
Article
Engineering, Electrical & Electronic
Lucas Jaloustre, Valentin Ackermann, Saron Sales De Mello, Sebastien Labau, Camille Petit-Etienne, Erwine Pargon
Summary: A study shows that a combination of lithography and Cl2-based plasma etching can effectively control the fabrication of GaN nanostructures, resulting in smooth nonpolar facets. The etching ability of specific crystallographic planes by chlorine atoms depends on the surface curvature, with fast-etch facets persisting in concave surfaces and slow-etch facets persisting in convex surfaces. This leads to the formation of a-type facets in pillar structures and m-type facets in hole structures during Cl2 plasma etching.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Engineering, Electrical & Electronic
Maolin Pan, Qiang Wang, Luyu Wang, Penghao Zhang, Yannan Yang, Lewen Qian, Xinlin Xie, Hai Huang, Saisheng Xu, Chunlei Wu, Chen Wang, Min Xu, David Wei Zhang
Summary: In this study, an NH3/N2 plasma surface treatment technique is developed to replenish the nitrogen vacancy on the etched AlGaN surface during p-GaN HEMTs fabrication. The effectiveness of the treatment is confirmed through XPS surface characterization. By using this technique, the drain current of severely over-etched devices can be recovered from 148 to over 300 mA/mm, accompanied by improved current collapse immunity, a threshold voltage of +1.5 V, and an Ion/Ioff ratio of over 1 x 108.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Physical
Heng-Sheng Shan, Ming-Hui Li, Xiao-Ya Li, Cheng-Ke Li, Sheng-Wei Liu, Yi-Fan Song, Yun-Jian Mei, Xiao-Dong Hao, Shu-Fang Ma, Bing-She Xu
Summary: The photoelectric conversion efficiency of InGaN/GaN multiple quantum well (MQW) solar cells decreased from 2.58% to 2.39% when the temperature was increased to 500°C. Analysis using atomic force microscopy (AFM) showed increased surface roughness and deterioration of crystal quality due to high-temperature treatment. X-ray diffraction analysis indicated an increase in the full width at half-maximum (FWHM) value and relaxation in the InGaN sample, suggesting degraded crystal quality in the active region. Photoluminescence (PL) spectroscopic measurements confirmed a decrease in peak intensity and a red shift in the peak wavelength in the PL spectrum. Scanning transmission electron microscopy (STEM) revealed uneven distribution of indium components and lattice distortion in the quantum well region after high-temperature treatment. First-principles calculations also confirmed the reduction in band gap and red shift in the peak wavelength due to atomic movement. The fluctuations in indium components and lattice distortion at 500°C led to an increase in nonradiative recombination centers, resulting in the degradation of photoelectric conversion efficiency in InGaN/GaN MQW solar cells.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Materials Science, Coatings & Films
Simon Ruel, Patricia Pimenta-Barros, Frederic Le Roux, Nicolas Chauvet, Michel Massardier, Philippe Thoueille, Shirley Tan, Daniel Shin, Francois Gaucher, Nicolas Posseme
Summary: In this paper, the plasma-etching steps during the fabrication of a MOS-HEMT were investigated for their potential damage to GaN materials. The study compared the Cl-2-based atomic layer etching (ALE) process with He or Ar as the sputtering gas, examining the self-limiting synergy and process window of ALE. A comparison was also made to a steady-state process, evaluating roughness and electrical measurements to assess induced damage.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Chemistry, Physical
Naoto Kumagai, Hirotomo Itagaki, Jaeho Kim, Shingo Hirose, Hajime Sakakita, Xue-lun Wang
Summary: In this study, the application of plasma-induced MOCVD for epitaxial growth of III-V nitride semiconductors was examined. The GaN surface exposed to NH3 plasma was characterized using physical and chemical techniques. The comprehensive characterizations revealed that plasma exposure for several minutes did not cause significant damage to the GaN surface, and optical techniques showed higher sensitivity in detecting the effect of plasma exposure.
APPLIED SURFACE SCIENCE
(2022)
Article
Construction & Building Technology
Rongjin Cai, Hailong Ye
Summary: The study investigates the degradation mechanisms of clinkerless alkali-activated slag based ultra-high strength concrete (AAS-UHSC) exposed to high temperatures up to 800 degrees C. It demonstrates the beneficial roles of potassium incorporation in improving the thermal stability and integrity of AAS-UHSC. Unlike Portland cement clinker-based UHSC, AAS-UHSC shows no sign of explosive spalling, likely due to the presence of microcracks enhancing pore network connectivity.
CEMENT AND CONCRETE RESEARCH
(2021)
Article
Nanoscience & Nanotechnology
T. S. Orlova, A. M. Mavlyutov, M. Yu. Gutkin
Summary: The effect of decreased temperatures on the annealing-induced hardening of ultrafine-grained aluminum of commercial purity was revealed and discussed. The study showed that there is a critical deformation temperature at which the AIH effect is completely suppressed. The experimental results are consistent with the theoretical explanation provided.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Medicine, General & Internal
Yu Dong, Ying Chen, Baoguo Yao, Peng Song, Ruiting Xu, Rui Li, Ping Liu, Yu Zhang, Li Mu, Xin Tong, Linwei Ma, Jianjun Yu, Li Su
Summary: This study aimed to explore the molecular mechanism of neuropathological damage induced by radiofrequency ablation at different temperatures. The results showed that with the increase in temperature, nerve conduction velocity gradually decreased, and the degree of neuronal degeneration gradually increased. Furthermore, the temperature-induced damage was closely associated with the expression of SCN9A, SCN3B, and NFASC proteins.
Article
Materials Science, Multidisciplinary
Yu-Shuang Wang, Jian-Ying Wu
Summary: In this work, the previous thermodynamically consistent energy-based elastoplastic damage model is extended to concrete at high temperatures, successfully describing the material nonlinear behavior and providing numerical predictions of concrete structures. The proposed model incorporates mechanical damage variables and temperature-dependent mechanical properties to effectively describe the behavior of concrete at high temperatures.
INTERNATIONAL JOURNAL OF DAMAGE MECHANICS
(2023)
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
Multidisciplinary Sciences
Ah Hyun Park, Seungjae Baek, Young Won Kim, S. Chandramohan, Eun-Kyung Suh, Tae Hoon Seo
Summary: This study demonstrates the use of a defect-selective-etched (DSE) porous GaN layer as a buffer layer for InGaN/GaN LED development. The overgrown GaN epilayer on the DSE porous GaN exhibits reduced threading dislocations (TDs) and relaxation of compressive stress compared to the conventional GaN epilayer. The enhanced internal quantum efficiency of the InGaN/GaN LEDs is attributed to stress relaxation and TDs annihilation.
Article
Physics, Applied
Andreo Crnjac, Mauricio R. Ramos, Natko Skukan, Michal Pomorski, Milko Jaksic
Summary: The research demonstrates that single crystal diamonds maintain excellent electronic properties at high temperatures, and radiation damage can lead to the formation of deep trapping levels. These deep trapping levels have an important impact on the performance of diamond detectors operating at high temperatures and under high radiation conditions.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Andrzej Taube, Maciej Kaminski, Marek Ekielski, Renata Kruszka, Joanna Jankowska-Sliwinska, Pawel P. Michalowski, Joanna Zdunek, Anna Szerling
Summary: The study focuses on the development of selective etching of p-GaN over Al0.25Ga0.75N for fabrication of AlGaN/GaN HEMTs with a p-GaN gate, achieving high etching selectivity and good electrical performance of the devices.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Engineering, Electrical & Electronic
Clint D. Frye, Catherine E. Reinhardt, Scott B. Donald, Lars F. Voss, Sara E. Harrison
Summary: This study investigates the effects of substrate temperature, RF power, and ICP power on GaN micropillar sidewall roughness and etch characteristics. The results show that adjusting these parameters can improve the sidewall etch morphology and produce extremely smooth surfaces suitable for GaN regrowth and new device structures.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Article
Physics, Applied
Koki Ono, Takashi Koide, Kenji Ishikawa, Hiromasa Tanaka, Hiroki Kondo, Ayae Sugawara-Narutaki, Yong Jin, Shigeo Yasuhara, Masaru Hori, Wakana Takeuchi
Summary: In this study, silicon carbide (SiC) was coated onto carbon nanowall (CNW) scaffolds, and the influence of wall edge width, wall-to-wall distance, and surface morphology was investigated. The results showed that SiC-coated CNW scaffolds could suppress calcification and promote cell proliferation.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Yerassyl Yerlanuly, Dennis Christy, Ngo Van Nong, Hiroki Kondo, Balaussa Ye Alpysbayeva, Rakhymzhan Zhumadilov, Renata R. Nemkayeva, Tlekkabul S. Ramazanov, Masaru Hori, Maratbek T. Gabdullin
Summary: This work presents experimental results on the synthesis of carbon nanowalls (CNWs) with predetermined morphology using two different methods, RF-PECVD and RI-PECVD. Microstructure analysis shows that the reproducibility of membrane morphology by CNWs is time-dependent. RF-PECVD leads to flat and thicker nanowalls, while RI-PECVD results in more vertical and self-supported nanowalls.
FULLERENES NANOTUBES AND CARBON NANOSTRUCTURES
(2023)
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.
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)