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植田 祥平; 今井 良行; 渡部 雅; 瀬川 智臣; Yan, X.
International Journal of Applied Ceramic Technology, 20(1), p.261 - 265, 2023/01
被引用回数：4 パーセンタイル：27.84(Materials Science, Ceramics)Ceramic stereolithography (CSL)-additive manufacturing (AM) technology is used to create a functionally graded ceramic (FGC) green body made of silicon carbide (SiC) and graphite. For the SiC/graphite FGC, the mixing parameters of ceramics powders and ultraviolet (UV) curing resin are improved, and correlations of the resultant slurry curing depth with integrated light intensity are discovered. Therefore, the SiC/graphite FGC-produced green body has no flaws, pores, or cracks on its surfaces. According to the association between cure depth and integrated light density for each slurry's composition, several interfacial collapses discovered in a cracked cross-section might be decreased.
湊 和生; 小川 徹
Comprehensive Nuclear Materials, 2nd Edition, Vol.5, p.334 - 360, 2020/08
高温ガス炉燃料として、微小燃料核を熱分解炭素及び炭化ケイ素で四重に被覆したTRISO被覆粒子燃料が開発されてきた。ここでは、TRISO被覆粒子燃料の高温での性能向上、核分裂生成物による被覆層腐食の抑制及び核分裂生成物の保持能力の向上、並びに高速中性子体系で使用できる燃料など、種々の先進的な被覆粒子燃料について、燃料概念,製造,検査方法,照射挙動等の結果を体系的にとりまとめた。2012年に刊行されたComprehensive Nuclear Materialsに掲載された同名論文の内容に、その後の研究開発の進展を加筆したものである。
Pham, V. H.; 永江 勇二; 倉田 正輝; 古本 健一郎*; 佐藤 寿樹*; 石橋 良*; 山下 真一郎
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.670 - 674, 2019/09
Silicon carbide (SiC) has recently attracted much attention as a potential material for accident tolerant fuel cladding. To investigate the performance of SiC in severe accident conditions, study of steam oxidation at high temperatures is necessary. However, the study focusing on steam oxidation of SiC at temperatures above 1600
C is still certainly limited due to lack of test facilities. With the extreme oxidation/corrosion environment in steam at high temperatures, current refractory materials such as alumina and zirconia would not survive during the tests. Application of laser heating technique could be a great solution for this problem. Using laser heating technique, we can localize the heat and focus them on the test sample only. In this study, we developed a laser heating facility to investigate high-temperature oxidation of SiC in steam at temperature range of 1400-1800C for 1-7 h. The oxidation kinetics is then being studied based on the weight gain and observation on cross-sectioned surface of tested sample using field emission scanning electron microscope. Off-gas measurement of hydrogen (H
) and carbon monoxide (CO) generated during the test is also being conducted via a sensor gas chromatography. Current results showed that the SiC sample experienced a mass loss process which obeyed paralinear laws. Parabolic oxidation rate constant and linear volatilization rate constant of the process were calculated from the mass change of the samples. The apparent activation energy of the parabolic oxidation process was calculated to be 85 kJ.mol
. The data of the study also indicated that the mass change of SiC under the investigated conditions reached to its steady stage where hydrogen generation became stable. Above 1800C, a unique bubble formation on sample surface was recorded.
山下 真一郎; 永瀬 文久; 倉田 正輝; 野澤 貴史; 渡部 清一*; 桐村 一生*; 垣内 一雄*; 近藤 貴夫*; 坂本 寛*; 草ヶ谷 和幸*; et al.
Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 10 Pages, 2017/09
我が国では、事故耐性燃料の技術基盤を整備するために2015年に軽水炉の事故耐性燃料等(ATFs)に関する研究開発プロジェクトが立ち上がった。日本原子力研究開発機構は、国内のプラントメーカ, 燃料メーカ, 大学等が有する国内軽水炉においてジルカロイを商用利用した際の経験、知識を最大限活用するために、これらの機関と協力して本プロジェクトを実施するとともに取りまとめを行っている。プロジェクトの中で検討されているATF候補材料は、微細な酸化物粒子を分散することで強化されたFeCrAl鋼(FeCrAl-ODS鋼)と炭化ケイ素(SiC)複合材料であり、通常運転時の燃料性能は同等かそれ以上で、事故時にはジルカロイよりも長い時間原子炉炉心においてシビアアクシデント条件に耐えることが期待されている。本論文では、日本のプロジェクトで実施中の研究開発の進捗について報告する。
岩本 直也*; Azarov, A.*; 大島 武; Moe, A. M. M.*; Svensson, B. G.*
Materials Science Forum, 858, p.357 - 360, 2016/05
Thermal stability of deep level defects in high purity semi-insulating (HPSI) 4H-Silicon Carbide (SiC) substrates was studied. The samples were annealed from 700 to 1700 C, and Schottky barrier diodes (SBDs) were fabricated on the samples. The SBDs were characterized by current-voltage, capacitance-voltage and admittance spectroscopy measurements. The forward current of SBDs increased substantially with the increase of annealing temperature, while the reverse leakage current remained below 10
A. The capacitance of the samples annealed at 1400 and 1500 C was essentially zero at bias voltages between 0 and 10 V, but after 1600 and 1700 C annealing, the capacitance increased and started to respond to the bias voltage. The net hole concentrations in the 1600 and 1700 C annealed substrates were estimated to be 0.5
1
10
and 1410
/cm
, respectively. From admittance spectroscopy, five defect levels were detected. Defect peaks relating to boron acceptors increased although defect peaks with deep levels decreased with increasing annealing temperature. Therefore, it can be concluded that deep levels which act as compensation centers for boron acceptors dissociate by high temperature annealing, and as a results, hole concentration increases.
Lohrmann, A.*; Castelletto, S.*; Klein, J. R.*; 大島 武; Bosi, M.*; Negri, M.*; Lau, D. W. M.*; Gibson, B. C.*; Prawer, S.*; McCallum, J. C.*; et al.
Applied Physics Letters, 108(2), p.021107_1 - 021107_4, 2016/01
被引用回数：45 パーセンタイル：83.54(Physics, Applied)Creation and characterisation of single photon emitters near the surface of 4H- and 6H-silicon carbide bulk substrates and 3C-SiC epitaxially grown on silicon substrates were investigated. These single photon emitters can be created and stabilized by thermal annealing in an oxygen atmosphere at temperatures above 550 C. Hydrofluoric acid (HF) treatment is shown to effectively annihilate the emission from defects and to restore an optically clean surface. However, the emission from the defects can be obtained after re-oxidation above 550 C. By measuring using standard confocal microscopy techniques, the excited state lifetimes for the emitters are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice.
武山 昭憲; 出崎 亮; 杉本 雅樹; 吉川 正人
Journal of Asian Ceramic Societies (Internet), 3(4), p.402 - 406, 2015/12
Ceramic yield, density, volume change and pore size distribution were measured for radiation- and thermally cured (poly carbo silan) PCS powder when they were pyrolyzed in the temperature ranges between 673 and 973 K. Higher ceramic yield was obtained for radiation-cured powder due to smaller amount of evolved gas. Temperature dependence of volume change and the total pore volume show the formation and disappearance of pores in the powders were determined by the volume shrinkage and evolution of decomposed gases. Volume shrinkage narrowed the pore size distribution for radiation-cured powder. For thermally cured powder, the narrowing of size distribution was disturbed by aggregated pores. Smaller amount of evolved gas from radiation-cured powder relative to thermally cured powder prevented the aggregation of pores and provided the narrow size distribution.
Kraus, H.; Simin, D.*; Fuchs, F.*; 小野田 忍; 牧野 高紘; Dyakonov, V.*; 大島 武
Proceedings of 11th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-11) (Internet), p.176 - 179, 2015/11
Quantum centers in silicon carbide (SiC) have already transcended their former reputation as mere performance-hampering defects. Especially the silicon vacancies, but also other point defects offer a variety of quantum applications, completing and complementing the successful NV centers in diamond. We aim to provide an overview over the research activities on quantum centers in silicon carbide, from fundamental knowledge on the 3/2 spin multiplicity, over microwave emission and single photon sources, to axis-aware magnetic field sensing and temperature sensing. Finally, we discussed creating tailored defects in SiC using different radiation parameters.
土方 泰斗*; 三友 啓*; 松田 拓磨*; 村田 航一*; 横関 貴史*; 牧野 高紘; 武山 昭憲; 小野田 忍; 大久保 秀一*; 田中 雄季*; et al.
Proceedings of 11th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-11) (Internet), p.130 - 133, 2015/11
In order to develop semiconductor devices with MGy radiation resistivity, we are developing power metal-oxide-semiconductor field-effect-transistors (MOSFETs) based on silicon carbide (SiC) semiconductors. The 
-ray irradiation responses of power SiC-MOSFETs were studied under various irradiation temperatures and humidity with various gate-bias conditions. Making comparisons between these responses, the optimum device operating condition and a better device structure were derived and MGy resistivity was achieved. Besides, -ray irradiation tests for a motor-driver circuits consisting of SiC-MOSFETs were carried out, and as a result, their continuous operation up to 2 MGy was confirmed.
成澤 雅紀*; 江夏 昌志; 武山 昭憲; 杉本 雅樹; 出崎 亮; 佐藤 隆博; 外薗 洋樹*; 河相 武利*; 岩瀬 彰宏*
Journal of the Ceramic Society of Japan, 123(9), p.805 - 808, 2015/09
Two kinds of Si-O-C(-H) ceramics particles having intrinsic photoluminescence (PL) spectra were prepared from silicone resin microspheres by heat treatment in a hydrogen atmosphere at 800 or 1100C. The obtained particles were painted on a Si substrate using a binder, and ion-beam-luminescence spectra were observed under proton beam irradiation with an acceleration energy in the ranges of 1-3 MeV. Observed spectra had peaks at wavelength of 520-540 nm. These peak wavelengths were larger than those observed under UV light irradiation. The luminescence of H 1100 (sample decarbonized at 1100C) was bright, and that of H 800 (sample decarbonized at 800C) was faint. However, the intensity of luminescence decreased rapidly at an early stage of the beam irradiation. In air, a sharp luminescence band with a peak at 300 nm appeared together with the main emission with a peak in the range of 520-540 nm. The existence of the sharp band at 300 nm was apparent in the H 800 spectra, whereas it appeared as a minor peak in the H 1100 spectra in air.
Widmann, M.*; Lee, S.-Y.*; Rendler, T.*; Son, N. T.*; Fedder, H.*; Paik, S.*; Yang, L.-P.*; Zhao, N.*; Yang, S.*; Booker, I.*; et al.
Nature Materials, 14(2), p.164 - 168, 2015/02
被引用回数：499 パーセンタイル：99.57(Chemistry, Physical)Single silicon vacancy (V
) in silicon carbide (SiC) was studied from the point of view of single photon source for quantum computing. The V centers were created in high purity semi-insulating hexagonal (4H)-SiC by 2 MeV electron irradiation with fluences up to 510 /cm
. No subsequent annealing was carried out. A couple of solid immersion lens (SIL) with 20 
m diameter were created on samples by ion milling using 40 keV Ga focused ion beam. A typical home-built confocal setup was used after optimizing for emission in the wavelength range around 900 nm. As a result, optically detected electron spin resonance (ODMR) for V was observed at room temperature (RT). Using ODMR, Rabi oscillations were also observed, and the Rabi frequency increased with increasing applied-magnetic field. In addition, spin relaxation time T
and T were detected to be 500 s and 160 s, respectively.
Christle, D.*; Falk, A.*; Andrich, A.*; Klimov, P.*; Hassan, J.*; Son, N. T.*; Janz
n, E.*; 大島 武; Awschalom, D.*
Nature Materials, 14(2), p.160 - 163, 2015/02
被引用回数：376 パーセンタイル：99.24(Chemistry, Physical)Carbon vacancy - silicon vacancy pair (V
-V) in silicon carbide (SiC) is regarded as a promising candidate for a qubit for quantum computing since V-V is thought to have electronic states with sharp optical and spin transitions. However, single spin operation using V-V has not yet been succeeded although it was revealed that V-V shows the characteristics as a single photon source (SPS). In this study, we studied spin properties of V-V created in SiC by 2 MeV-electron irradiation. First, we found V-V in SiC using a confocal microscope (CFM) and measured their optical detected magnet resonance (ODMR) at 20 K. Then, their spin coherence was measured from the standard two-pulse Hahn-echo sequence using ODMR. As a result, the spin coherence time exceeding 1 ms was obtained.
Castelletto, S.*; Johnson, B. C.*; Zachreson, C.*; Beke, D.*; Balogh, I.*; 大島 武; Aharonovich, I.*; Gali, A.*
ACS Nano, 8(8), p.7938 - 7947, 2014/08
被引用回数：91 パーセンタイル：90.23(Chemistry, Multidisciplinary)Single Photon Sources (SPSs) in cubic (3C) Silicon Carbide (SiC) Nano Particles (NPs) were investigated. As a result, photo luminescence (PL) with broad emission at wavelength ranges between 600 and 800 nm was observed from 3C-SiC NPs at room temperature. The second order photon auto-correlation measurements revealed that defect with the PL characteristic is SPSs. The intensity and stability of the PL increased when samples were irradiated with electrons and subsequently annealed at 500 C. From PL measurements at low temperature and theoretical analysis using spin-polarized density functional theory, the defect can be identified as carbon-antisite carbon-vacancy pair (CV).
水田 栄一*; 久保山 智司*; 阿部 浩之; 岩田 佳之*; 田村 貴志*
IEEE Transactions on Nuclear Science, 61(4), p.1924 - 1928, 2014/08
被引用回数：113 パーセンタイル：99.27(Engineering, Electrical & Electronic)Radiation effects in silicon carbide power MOSFETs caused by heavy ion and proton irradiation were investigated. In the case of ions with high LET, permanent damage (increase in both drain and gate leakage current with increasing LET) was observed and the behavior is similar to the permanent damage observed for SiC Schottky Barrier diodes in our previous study. In the case of ions with low LET, including protons, Single Event Burnouts (SEBs) were observed suddenly although there was no increase in leakage current just before SEBs. The behavior has not been observed for Si devices and thus, the behavior is unique for SiC devices.
加藤 正史*; 吉原 一輝*; 市村 正也*; 畑山 智亮*; 大島 武
Japanese Journal of Applied Physics, 53(4S), p.04EP09_1 - 04EP09_5, 2014/04
被引用回数：7 パーセンタイル：29.18(Physics, Applied)Deep levels in p-type hexagonal (4H) silicon carbide (SiC) epilayers irradiated with and without electrons at 160 keV and subsequent annealing at 1000 C were investigated. Current deep level transient spectroscopy (I-DLTS) was applied to investigate deep levels. As a result, Deep levels with activation energies less than 0.35 eV which are located near the valence band were detected. Also, two deep levels (AP1 and AP2) existed in all samples. Other deep levels appeared after the electron irradiation. Since electrons with an energy of 160 keV can knock-on only carbon atoms from the lattice site of SiC, it was concluded that the deep levels observed after irradiation were related to carbon vacancy V.
三宅 景子*; 安田 智成*; 加藤 正史*; 市村 正也*; 畑山 智亮*; 大島 武
Materials Science Forum, 778-780, p.503 - 506, 2014/02
Photolytic hydrogen generation using sunlight is regarded as energy production technology for the next generation. One of the key of issues for this technology is a selection of materials for the photolysis. Silicon carbide (SiC) is expected as one of the candidate materials for this application. In this study, we measured carrier lifetimes in SiC by the microwave photoconductivity decay (PCD) method. In order to control carrier lifetime in SiC, some samples were irradiated with 160 keV-electrons with fluences between 110
and 110
/cm. The values of carrier lifetime in SiC were compared to photocurrents in electrolytes which directly relate to the conversion efficiency of photolytic hydrogen generation. As a result, photocurrents depend on the sum of the depletion layer width and the diffusion length which was estimated from carrier lifetimes.
中根 浩貴*; 加藤 正史*; 市村 正也*; 大島 武
Materials Science Forum, 778-780, p.277 - 280, 2014/02
Annealing behavior of the carrier lifetime and the deep levels in electron irradiated n-type and semi-insulating hexagonal (4H) silicon carbide (SiC) was studied. As a result of photo induced current transient spectroscopy (PICTS) measurements, two peaks were observed for each sample. The height of those peaks depended on annealing temperature. Comparing the annealing behavior of the peak height with temperature dependence of concentrations of various defects reported previously, we speculated that the observed peaks originate from either divacancy of silicon vacancy and carbon vacancy (VV) or pair of carbon antisite and carbon vacancy (CV).
C and 1500C and measurements of lifetime and photoluminescenceKlahold, W. M.*; Devaty, R. P.*; Choyke, W. J.*; 河原 洸太朗*; 木本 恒暢*; 大島 武
Materials Science Forum, 778-780, p.273 - 276, 2014/02
Ultra-pure n-type (810
cm
), 99 m thick epitaxial layers of hexagonal (4H) silicon carbide (SiC) were irradiated with electrons either at 170 keV with a fluence of 510 cm
or at 1 MeV with a fluence of 110 cm in various geometries. Low temperature photoluminescence (LTPL) spectra and microwave photoconductance (PCD) lifetime measurements were carried out for all samples before and after annealing in argon in free standing mode or on a POCO carbon (Poco Graphite, Inc.) platform, every 50 C from 1100 C to 1500 C. However, no improvement in carrier lifetime was observed although previous studies reported that carbon diffused into SiC during high temperature treatment improves carrier lifetime. The result obtained in this study suggests that simple carbon diffusion model cannot be applied and more study is required to understand the injection of carbon interstitials into the SiC lattice.
出崎 亮; 杉本 雅樹; 吉川 正人; 田中 茂; 成澤 雅紀*; 岡村 清人*; 伊藤 正義*
Journal of Materials Science, 42(1), p.130 - 135, 2007/01
被引用回数：3 パーセンタイル：13.77(Materials Science, Multidisciplinary)われわれは、液体のケイ素系ポリマーであるポリビニルシラン(PVS)から線架橋を利用してSiC微小成型体を作製している。得られるSiC微小成型体の特性と焼成条件の間には密接な関係があるので、PVSのセラミックス化過程を調べ、最適な焼成条件を見いだすことが重要である。本報では、室温で線架橋されたPVSのセラミックス化過程をガス分析,熱重量分析,密度変化等の面から調べた。線架橋PVSのセラミックス化は500K以上の温度で始まり、700-1100Kの温度域で急激な有機-無機変成が起こることが明らかになった。質量変化と密度変化の結果から、放射線架橋、及びその後の焼成過程におけるPVSの体積収縮率が80%であることを明らかにした。1573Kでの焼成によって得られたSiCについて、密度が2.50g/cm、微小ビッカース硬さが31.6GPaであった。
馬場 祐治; 関口 哲弘; 下山 巖; Nath, K. G.
Applied Surface Science, 237(1-4), p.176 - 180, 2004/10
被引用回数：9 パーセンタイル：43.21(Chemistry, Physical)炭化ケイ素(SiC)はシリコンに代わる次世代の半導体物質として期待されている。SiC薄膜の製造法の一つに、有機ケイ素化合物を用いた蒸着法が知られており、ミクロンオーダーの厚みを持つSiC薄膜が合成されている。本研究では、ナノメートルオーダーの厚みを持つ極薄SiCの構造を調べるため、テトラメチルシランを放電気体として用いたイオンビーム蒸着法により1原子層以下のSiCをグラファイト上に堆積させ、その電子構造を放射光光電子分光法,X線吸収微細構造法により調べた。その結果、0.1ナノメーターの厚みの蒸着層を850Cまで加熱すると、バルクのSiCと異なった二次元構造を持つSiCが生成することがわかった。この物質のX線吸収微細構造スペクトルの偏光依存性を測定したところ、Si原子周辺に
*軌道的な性質を持つ軌道が存在し、この*軌道が表面に垂直であることがわかった。このことから、得られたSiC膜は、グラファイトと同様な二次元状の構造をとることが明らかとなった。
