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In this study, we proposed a novel membrane-heater integrated LSI for on-site annealing-recovery from TID effect with low energy consumption, aiming at solving the problem of IC damage by gamma ray irradiation. The heater and membrane structure were fabricated around the LSI by using integrated MEMS technology. 20 kGy gamma-ray irradiation was performed later on the LSI samples and then the irradiated samples were annealed for recovery by integrated membrane-heater. It was found that the current of LSI decreased after irradiation and almost recovered to the original level after 15-minutes annealing at 300 ℃. We report, for the first time, the successful recovery of LSI with 15 minutes from 20 kGy gamma-ray TID damage by using an integrated membrane-heater., The 34th International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2021)

Gallium oxide (Ga2O3) has emerged as a new competitor to SiC and GaN in the race toward next-generation power switching and harsh environment electronics by virtue of the excellent material properties and the relative ease of mass wafer production. In this proceedings paper, an overview of our recent development progress of Ga2O3 metal-oxide-semiconductor field-effect transistors and Schottky barrier diodes will be reported. © Copyright 2018 SPIE.

Historically, the exploration of III-V compound semiconductors has begun with small bandgap materials and proceeded to large bandgap ones in recent years, that is, from GaAs-based compounds to GaN-based ones. We consider that gallium oxide (Ga2O3) is no exception in following this history and is poised to become the next mainstream of compound semiconductor research due to its attractive material properties based on an extremely large bandgap of about 4.5 eV [1]. This bandgap energy is not only much larger than those of representative wide bandgap semiconductors such as GaN and SiC but also unique among single-crystal semiconductors. Furthermore, Ga2O3 has another important advantage for commercialization over the other wide bandgap materials in that large-size, high-quality bulk single crystals can be synthesized by melt growth methods, thus allowing native substrates to be produced at a relatively low cost [2]. Recently, these two features have drawn much attention to Ga2O3, resulting in a rapid expansion of the Ga2O3 community. © 2018 IEEE.

Gallium oxide (Ga2O3) is attractive for power devices owing to its wide bandgap of 4.5 eV and the availability of economical device-quality native substrates. Research on Ga2O3 Schottky barrier diodes and field-effect transistors (FETs) has seen rapid recent progress [1]. An unexplored area of immense interest is the radiation tolerance of these devices, whose high-voltage and high-temperature capabilities are expected to find applications in extreme radiation environments such as space and nuclear facilities that impose stringent reliability requirements to ensure stable operations. This paper reports the first investigation into the effects of ionizing radiation on Ga2O3 metal-oxide-semiconductor FETs (MOSFETs). A gamma-ray (y-ray) tolerance as high as 230 kGy(SiO2) was demonstrated for the bulk Ga2O3 channel by virtue of the MOSFETs' stable on-current, on-resistance (Ron), and threshold voltage (Vt) against irradiation. Hysteresis in the transfer characteristics remained negligible after exposure to the highest dose. Radiation-induced degradations in the gate insulation and surface passivation, which could be attributed to dielectric damage and interface trap generation, were found to limit the overall radiation resistance of these devices. © 2017 IEEE.

ゾル-ゲル法によってプレカーサー繊維を作製し、それを硫化水素雰囲気で熱処理後、引き続き酸素雰囲気中で熱処理することによって、硫黄添加二酸化チタン繊維を作製した。繊維の結晶構造は二酸化チタンのアナターゼ構造であり、光触媒効果の発現に適した結晶構造であることがわかった。光学特性の評価の結果、硫黄添加二酸化チタン繊維はアナターゼ構造よりも見かけ上約0.06eV短いバンドギャップを持ち、より多くの量の可視光を吸収できることがわかった。元素分析の結果から、繊維中には硫黄原子が約0.58原子%添加されており、また二酸化チタンの酸素原子と置換した位置に添加されていることがわかった。この硫黄添加二酸化チタン繊維を用いてトリクロロエチレンの分解実験を行ったところ、可視光照射下においてトリクロロエチレン濃度の減少と二酸化炭素の発生が確認された。このことから、硫黄添加二酸化チタン繊維が可視光照射下で光触媒効果を発現可能であることがわかった。, The Sol-Gel derived precursor fiber was annealed under hydrogen disulfeid (H2S) following oxygen atmosphere, Sulfer-doped titanium dioxide (TiO2) fiber was obtained. Crystal structure of the fiber was identified as anatase phase of TiO2. The energy band gap of the fiber was narrower by about 0.06 eV than that of anatase, which showed that it could absorb visible light. The fiber contains about 0.58 atomic % of Sulfer, and they located at the oxygen lattice site of TiO2. Under visible light illumination, the fiber degraded Trichroloethylen (TCE) and produced carbon dioxide (CO2). This shows Sulfer-doped TiO2 fiber has the photocatalytic activity under visible light illumination., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2007-012