2024年11月, 令和6年度電気学会東京支部茨城支所研究発表会 優秀発表賞 (指導学生), 低温・バイアス下におけるマグネシウムシリサイドフォトダイオードの分光感度, 電気学会東京支部茨城支所
古田良輔,(勝俣響, 坂根駿也, 鵜殿治彦)

2024年11月, 令和6年度電気学会東京支部茨城支所研究発表会 優秀発表賞（指導学生）, シリコン基板上のInSbのスパッタ成膜, 電気学会東京支部茨城支所
小金澤藍登;久保田啓聖;鮎川瞭仁;坂根駿也;鵜殿治彦

2024年11月, The 21st ICFD (2024), Best Presentation Award for Young Researcher（指導学生）, Epitaxial Growth of High-quality Mg3Sb2-based Thin Films and Their Thermoelectric Properties, Institute of Fluid Science, Tohoku University
Akito Ayukawa;N Kiridoshi;T Kuriyama;W Yamamoto;A Yasuhara;H Udono;S Sakane

2024年03月, 第56回（2024年春季）応用物理学会講演奨励賞（共同研究者）, サファイア基板上エピタキシャルMg3Sb2薄膜の熱電特性評価, 応用物理学会
坂根 駿也;鮎川;瞭仁;切通 望;綿引 詩門;鵜殿 治彦

2023年09月, 第55回（2023年秋季）応用物理学会講演奨励賞（指導学生）, 熱光発電に向けたMg2Siフォトダイオードの電流電圧特性の評価, 応用物理学会
宮後 大介(坂根駿也, 鵜殿治彦)

2022年12月, Semicon Japan, Academia Awards スポンサー賞, マグネシウムシリサイド半導体を用いた赤外線センサと熱光発電セルの開発, SEMI, Japan
茨城大学半導体研究室(鵜殿治彦、中村陸斗、宮後大介)
出版社・新聞社・財団等の賞

2022年12月, 令和4年度電気学会東京支部茨城支所研究発表会 優秀発表賞 口頭発表(指導学生), 反応性イオンエッチングによるMg2Si基板表面の微細加工, 電気学会東京支部茨城支所
中村陸斗(中村陸斗、鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2022年12月, 令和4年度電気学会東京支部茨城支所研究発表会 優秀発表賞 口頭発表(指導学生), Mg2SiウェハのXRCピークとX線回折角の関係, 電気学会東京支部茨城支所
梅原 翼(梅原 翼;鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2021年12月, 令和3年度電気学会東京支部茨城支所研究発表会 優秀発表賞 口頭発表(指導学生), メッシュ状電極Mg2Siフォトダイオードの温度依存性, 電気学会東京支部茨城支所
市川雄大(市川雄大;吉田美沙、津谷大樹、鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2021年12月, 令和3年度電気学会東京支部茨城支所研究発表会 優秀発表賞 口頭発表(指導学生), リンイオン注入プロセスによるMg2Si-PDの作製, 電気学会東京支部茨城支所
中村陸斗(中村陸斗、鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2019年07月, Young Scientist Award (APAC-Silicide 2019)(指導学生）, Comparison of crystalline quality and electrical property of Mg2Si crystals grown using PBN and PG graphite crucible, Committee of APAC-Silicide 2019, JSAP
Y. Fuse(Y. Fuse;R. Masubuchi;T. Ishikawa;K. Gosyuu;H. Udono)
国際学会・会議・シンポジウム等の賞

2018年11月, 平成30年度電気学会東京支部茨城支所研究発表会 学生発表優秀賞口頭発表(指導学生), OCVD法によるMg2Siのライフタイム評価, 電気学会東京支部茨城支所
高橋史也(高橋史也;鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2018年11月, 平成30年度電気学会東京支部茨城支所研究発表会 学生発表優秀賞口頭発表(指導学生), Znを添加したMg2Sn結晶の融液成長, 電気学会東京支部茨城支所
佐藤彰(佐藤彰;小谷野慈;菅原劉丞;鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2017年11月, 平成29年度電気学会東京支部茨城支所研究発表会 学生発表優秀賞ポスター(指導学生), 溶融Mg2Si結晶の添加不純物による酸化効果への影響, 電気学会東京支部茨城支所
金田大(金田大;今野嵩;鵜殿治彦)
国内学会・会議・シンポジウム等の賞

2016年12月, 平成28年度電気学会東京支部茨城支所研究発表会 学生発表優秀賞ポスター(指導学生), Mg2Siを用いたフォトダイオードの光検出器としての性能評価, 電気学会東京支部茨城支所
秋山智洋(秋山智洋;鬼沢雄馬;中野達哉;鵜殿 治彦;谷川俊太郎;津谷大樹)
国内学会・会議・シンポジウム等の賞

2016年07月, Young Scientist Award (APAC-Silicide 2016)指導学生, Committee of APAC-Silicide 2016, JSAP
Syu Konno(S. Konno;T. Otsubo;K. Nakano;H. Udono
国際学会・会議・シンポジウム等の賞

2015年03月, 第75回応用物理学会秋季学術講演会 講演奨励賞（指導学生）, 応用物理学会
堀信彦;江坂文孝;鵜殿治彦
国内学会・会議・シンポジウム等の賞

2014年11月, 第22回電気学会茨城支所 学生発表優秀賞口頭発表(指導学生), Mg2Si溶融結晶の格子熱伝導率の低減と熱電性能の改善, 電気学会東京支部茨城支所
大坪翼, 大竹秀明, 鵜殿治彦

2014年11月, 第22回電気学会茨城支所 学生発表優秀賞ポスター発表(指導学生), Mg2Si溶融結晶の格子熱伝導率の低減と熱電性能の改善, 電気学会東京支部茨城支所
石井慶祐, 大竹秀明, 大坪翼, 鵜殿治彦

2014年07月, Young Scientist Award (ICSS-Silicide 2014)(指導学生）, Evaluation of Mg2Si pn-junction depth by sputter etching, Committee of ICSS-Silicide 2014, JSAP
N. Hori;S. Hasunuma;F. Esaka;H. Udono

2013年11月, 第21回電気学会茨城支所 学生発表優秀賞口頭発表(指導学生), マグネシウムシリサイド単結晶への不純物共添加効果, 電気学会東京支部茨城支所
大竹秀明,蓮沼慎,鵜殿治彦

2013年11月, 第21回電気学会茨城支所 学生発表優秀賞ポスター発表(指導学生), Mg2Si pn接合ダイオードの接合深さによる受光特性への影響, 電気学会東京支部茨城支所
堀信彦,鵜殿治彦,竹崎誠朗,大徳健太

2013年11月, 第21回電気学会茨城支所 学生発表優秀賞ポスター発表(指導学生), Mg2Si pn接合ダイオードの分光特性改善, 電気学会東京支部茨城支所
大徳 健太,竹崎 誠朗,打越 雅仁,鵜殿 治彦

2013年11月, 第22回電気学会茨城支所 学生発表優秀賞口頭発表(指導学生), Mg2Si溶融結晶の格子熱伝導率の低減と熱電性能の改善, 電気学会東京支部茨城支所
大坪翼, 大竹秀明, 鵜殿治彦

2013年07月28日, Young Scientist Award (Asia-Pasific Conference on Green Technology with Silicides and Related Materials, APAC-Silicide 2013), Committee of APAC-Silicide 2013, JSAP
S. Kojima;M. Imai;T. Kume;K. Tanigaki;H. Tajima;H. Udono

2012年11月, 第20回電気学会茨城支所 学生発表優秀賞(指導学生), 不純物を添加したマグネシウムシリサイド結晶の成長, 電気学会東京支部茨城支所
蓮沼慎、石田大輔、鵜殿治彦

2010年11月, 第18回電気学会茨城支所 学生発表優秀賞(指導学生), 赤外受光素子用高純度MgSi結晶の電気特性, 電気学会東京支部茨城支所
八島研一、高橋良幸、御殿谷真、鵜殿治彦

2010年11月, 第18回電気学会茨城支所 学生発表優秀賞(指導学生), MgSiの結晶性と熱伝導率の関係, 電気学会東京支部茨城支所
國政恵美、高橋良幸、石田大輔、八島研一、磯田幸宏、上田聖、鵜殿治彦

2007年12月, 電気学会茨城支所 学生発表優秀賞(指導学生), Mg2Sn結晶の成長と評価, 電気学会東京支部茨城支所
串田圭祐、杉本和大、小口裕之、御殿谷真、鵜殿治彦

2005年11月, 電気学会茨城支所 学生発表最優秀賞(指導学生), β-FeSi2単結晶の熱電特性評価, 電気学会東京支部茨城支所
鈴木弘和、鵜殿治彦、菊間勲

2004年01月, 研究奨励賞（高柳建次郎財団）, 波長1.5μｍ帯で発光するＳｉ系発光ダイオードに関する研究, 公益財団法人 高柳建次郎財団
鵜殿治彦
出版社・新聞社・財団等の賞

〔主要な業績〕Fabrication of Mg2Si linear photodiode arrays for SWIR imaging
Haruhiko Udono; Kaito Ojima; Naoki Imaizumi; Hideto Takei; Shunya Sakane, 筆頭著者, SPIE
Proc. of SPIE, Optical Components and Materials XXII, 2025年04月01日, ［査読有り］

〔主要な業績〕Evaluation of Mg2Si TPV cells fabricated on n-Mg2Si substrate by thermal diffusion of Ag acceptor
Takumi Shimizu; Daisuke Miyago; Kosuke Shimano; Shunya Sakane; Haruhiko Udono, 責任著者
Japanese Journal of Applied Physics, 2024年12月05日, ［査読有り］

〔主要な業績〕Record High Thermoelectric Figure of Merit of a III-V Semiconductor InGaSb by Defects Engineering via the Addition of Excess Constituent Elements
Nirmal Kumar Velu; Yasuhiro Hayakawa; Haruhiko Udono; Shunya Sakane; Yuko Inatomi, Materials with enhanced electron and reduced phonon transport properties are preferred for thermoelectric applications. The defect engineering process can optimize the interrelated electron and phonon transport properties to enhance thermoelectric performance. As the influence of various crystalline defects on the functional properties of materials is diverse, it is crucial to scale, optimize, and understand them experimentally. With this perspective, crystalline defects in InGaSb ternary alloys were engineered and their influence on the thermoelectric properties was studied experimentally. Crystalline defects such as point defects, dislocations, and compositional segregations were induced in In0.95Ga0.05Sb crystals by the addition of excess constituent elements, In, Ga, or Sb. The addition of excess Ga increased point defects, whereas excess Sb reduced dislocation densities. The thermoelectric figure of merit value (ZT) of In0.95Ga0.05Sb+Ga0.02 was recorded to be 0.87 at 573 K, which is the highest among other reported values of III-V semiconductors. The collective interactions of compositional segregations, point defects, and dislocations with electrons and phonons enhanced the ZT in this study.
ACS Applied Materials and Interfaces, 2024年09月04日, ［査読有り］

〔主要な業績〕Epitaxial growth of high-quality Mg₃Sb₂ thin films on annealed c-plane Al₂O₃ substrates and their thermoelectric properties
Akito Ayukawa; Nozomu Kiridoshi; Wakaba Yamamoto; Akira Yasuhara; Haruhiko Udono; Shunya Sakane, Abstract

High-quality epitaxial Mg₃Sb₂ thin films are promising thermoelectric materials to enable practical applications of compact and environmentally friendly thermoelectric conversion at room temperature. In this study, high-quality single-crystal Mg₃Sb₂ with high c-plane orientation were epitaxially grown directly on annealed c-Al₂O₃ substrates without passive layers. These thin films exhibited three times higher thermoelectric power factor than ever reported values due to high carrier mobility. The ultra-smooth surface of the annealed c-Al₂O₃ substrate facilitated the formation of high-quality Mg₃Sb₂ thin films without passive layers or polycrystalline interfaces that could be carrier scatters., IOP Publishing
Applied Physics Express, accepted, 2024年05月22日, ［査読有り］

〔主要な業績〕Precise synthesis of copper selenide nanowires with tailored Cu vacancies through photo-induced reduction for thermoelectric applications
Shunya Sakane; Tatsuki Miura; Kazuki Munakata; Yusuke Morikawa; Shunichiro Miwa; Riku Yamanaka; Toshiki Sugai; Akito Ayukawa; Haruhiko Udono; Hideki Tanaka, We have successfully synthesized Cu_2+xSe nanowires (NWs) with various amounts of Cu vacancies at room temperature by the photoreduction method for thermoelectric applications., Royal Society of Chemistry (RSC)
Nanoscale Advances, 2024年04月, ［査読有り］

〔主要な業績〕Control of Ag acceptor concentration and pn-junction depth in single crystalline Mg2Si photodiodes
Shunya Sakane; and Haruhiko Udono, 責任著者
AIP Advances, 2023年11月, ［査読有り］

〔主要な業績〕Effects of Te-doping on the thermoelectric properties of InGaSb crystals
V. Nirmal Kumar; Y. Hayakawa; H. Udono; and Y. Inatomi, Thermoelectric materials with optimum carrier concentration of the order of 1019–1020/cm3 are required to obtain a high figure of merit (ZT) value. As undoped In0.8Ga0.2Sb has a lower carrier concentration (~1016/cm3), Te impurity was doped between low (1 × 1018/cm3) and high level (1 x 1021/cm3) to understand the effects of doping on its thermoelectric properties. The undoped and Te-doped In0.8Ga0.2Sb crystals retained cubic zinc blende crystal structure irrespective of heavy doping of Te element. In addition to the optical phonon vibrational modes, acoustic phonon modes were also present when the doping concentration exceeded 1 × 1018/cm3. The carrier concentration in Te-doped In0.8Ga0.2Sb crystals were varied in the range 1018–1020/cm3. Te-doped In0.8Ga0.2Sb with concentration 1 × 1018/cm3 was recorded a higher power factor because of its lower resistivity and higher mobility than other crystals. The ZT of Te-doped In0.8Ga0.2Sb (1 × 1018/cm3) was higher than other samples at 300–450 K. This study revealed that the optimum Te dopant concentration to enhance the ZT value of InxGa1−xSb is 1 x 1018/cm3 for optimizing its properties toward mid-temperature thermoelectric applications.
J Mater Sci: Mater Electron, 2023年06月05日, ［査読有り］

〔主要な業績〕Thermoelectric properties of Zn-doped In0.95Ga0.05Sb crystals grown by directional solidification
V. Nirmal Kumar; Y. Hayakawa; H. Udono; and Y. Inatomi, Thermoelectric devices require p-type and n-type semiconductors with similar chemical, mechanical and thermoelectric properties to achieve maximum efficiency. To match with n-type In0.95Ga0.05Sb crystals for the fabrication of thermoelectric device, zinc (Zn) element was doped with In0.95Ga0.05Sb crystal intentionally to change its conductivity from n-type to p-type and its thermoelectric properties were studied. The Zn-doped In0.95Ga0.05Sb crystals grown by directional solidification were free from micro-cracks and their composition was distributed homogeneously. The carrier concentration was increased upon doping with Zn element. The resistivity of Zn-doped In0.95Ga0.05Sb increased with increasing temperature that showed degenerate semiconducting characteristics resulted from heavy doping. The Peierls distortion resulting from Sb–Sb interaction was observed in Zn-doped In0.95Ga0.05Sb crystals. The higher electron contribution and lower phonon contribution to total thermal conductivity were obtained in Zn-doped In0.95Ga0.05Sb than undoped crystals. The maximum ZT of 0.24 at 573 K was achieved by Zn-doped In0.95Ga0.05Sb with dopant concentration 1 × 1020 atoms/cm3. The ZT achieved is the highest among other reported values of p-type III–V semiconductors.
Journal of Materials Science, 2023年05月10日, ［査読有り］

〔主要な業績〕Study of deep levels in the Mg2Si grown by vertical Bridgman method
Kouki Fukushim; Naoki Mizunuma; Tatsuya Uematsu; Kyoko Shimizu; Takehiro Ota; Isao Tsunoda; Haruhiko UDONO; Kenichiro Takakura, Abstract

The electrical characteristics of a Mg₂Si p–n junction diode was investigated. The n-Mg₂Si substrate was grown by using the vertical-Bridgeman method. A p–n junction was fabricated by the thermal diffusion of Ag as an acceptor. The reverse current of the Au/Ag electrode diode was larger than that of the Ag electrode diode. The trap levels in the n-Mg₂Si bulk were investigated using deep-level transient spectroscopy. The magnitude of DLTS signal of E1 with the Au/Ag electrode diode was larger than that for the signals at the other trap levels. The E1 level corresponds to an Au-related trap that diffuses via thermal annealing during the alloying process. The open-circuit-voltage-decay study suggests the existence of a minority-carrier trap in n-Mg₂Si. The minority-carrier lifetime was shorter for Au/Ag electrode diodes. Therefore, Au may be involved in the formation of minority-carrier traps, as well as in the formation of majority-carrier traps., IOP Publishing
Jpn. J. Appl. Phys., 2023年05月01日, ［査読有り］

〔主要な業績〕Effect of Impurity Doping on Thermoelectric Properties of Melt-Grown Mg2Sn Crystals
Hidetsugu Motoki; Naofumi Tsuchiya; Sho Sato; Megumu Koyano; and Haruhiko Udono, 責任著者
JJAP Conf. Proc., 2023年04月26日, ［査読有り］

〔主要な業績〕Growth of 2-inch diameter Mg2Si crystal by the VGF method under Ar normal pressure
Tsubasa Umehara; Naoki Mizunuma; and Haruhiko Udono, 責任著者
JJAP Conf. Proc., 2023年04月26日, ［査読有り］

Analysis of grain growth behavior of multicrystalline Mg2Si
Deshimaru Takumi; Yamakoshi Kenta; Kutsukake Kentaro; Kojima Takuto; Umehara Tsubasa; Udono Haruhiko; Usami Noritaka
Jpn. J. Appl. Phys., 2022年11月28日, ［査読有り］

〔主要な業績〕Effects of dopant type and concentration on surface recombination velocity in hydrogen-terminated silicon
Nobue Araki; Haruhiko Udono, Abstract

Isolating the effects of the type and concentration of the dopant in lightly doped regions in the reaction between hydrogen-terminated silicon surface and atmospheric impurities in air is very difficult. However, changes in the surface recombination sites can be analyzed accurately through recombination lifetime measurements performed using the microwave photoconductive decay method. Thus, we investigated variations in the effective recombination lifetime in hydrogen-terminated silicon surfaces over time in air for different dopant types and concentrations. For both p-type and n-type silicon wafers, surface recombination velocity, S, increased with decreasing resistivity, namely, increasing dopant concentration. The time-dependent variations of the S for the p-type wafers decreased, and those for the n-type wafers increased with decreasing resistivity. Thus, it was shown that the time-dependent variation of the S depends on the type and concentration of the dopant used., IOP Publishing
Japanese Journal of Applied Physics, 2022年08月19日, ［査読有り］

〔主要な業績〕Silicon meets group-II metals in energy and electronic applications—How to handle reactive sources for high-quality films and bulk crystals
T. Suemasu; K.O. Hara; H. Udono; Manabu and M. Imai
J. Appl. Phys., 2022年05月20日, ［査読有り］, ［招待有り］

〔主要な業績〕Local structure analysis of Sb, Bi, and Ag dopant atoms in Mg2Si semiconductor by,x-ray absorption spectroscopy and first- principles calculation
Mamoru Kitaura; Shinta Wantanabe; Toshiaki Ina; Motoharu Imai; Haruhiko Udono; Manabu Ishizaki; Hisanori Yamane; Taku Tanimoto; and Akimasa Ohnishi, AIP Publishing
J. Appl. Phys., 2021年12月30日, ［査読有り］

〔主要な業績〕Single crystal growth of small-angle-grain-boundary-free Mg2Si via vertical Bridgman method
Ryohei Masubuchi; Babak Alinejad; Yoshiaki Hara; Haruhiko Udono, ラスト(シニア)オーサー, Elsevier BV
Journal of Crystal Growth, 2021年07月17日, ［査読有り］

Evaluation of Magnesium Tin Silicide Sintered Bodies Prepared by Liquid-Phase Pressure-Less Sintering
Inoue, H.; Kato, M.; Udono, H.; Kobayashi, T.
Materials Transaction, 2021年04月02日, ［査読有り］

Power Generation Efficiency of Thermoelectric Elements with a Trapezoidal Section
H. Inoue; H. Udono; M. Kato; T. Kobayashi
Journal of Electric Materials, 2020年10月29日, ［査読有り］

〔主要な業績〕Interface driven energy-filtering and phonon scattering of polyaniline incorporated ultrathin layered molybdenum disulphide nanosheets for promising thermoelectric performance
R. Abinaya a; J. Archana; S. Harish; M. Navaneethan; C. Muthamizhchelvan; S. Ponnusamy; H. Udono; R. Sugahara; Y. Hayakawa; M. Shimomura, The hybrid of organic conducting polymers and inorganic materials with ultralow thermal conductivity, which is a promising strategy for the realization of polymer based effective thermoelectric (TE) applications. In this work, ultrathin layered molybdenum disulphide (MoS2) nanosheets/PANI nanocomposites are prepared by hydrothermal route. The effect of varying PANI wt% in the nanocomposites and its interface effect on thermoelectric properties are well investigated. The successful incorporation of PANI between the MoS2 layers confirmed by high resolution transmission electron microscope (HRTEM). The significantly enhanced potential difference of MoS2/ PANI nanocomposites with increasing PANI content is well clarified by the increased Seebeck value. The variable range hopping property is identified and conductivity is raised up highly due to insertion of PANI in layered van der Waal's gap of MoS2. The effective interface facilitates charge for fast transport. The reduced thermal conductivity is observed of about 0.248 W*m−1*K−1 for 2.5 wt% addition of PANI. The key factor is that the stability of the sample is improved for MoS2/ PANI nanocomposites than pristine MoS2. Our work paved a new approach to improve TE performance by preparing TE MoS2 material through simple chemical route.
Journal of Colloid and Interface Science, 2020年09月23日, ［査読有り］

First principle band calculations of Mg2Si thin films with (001) and (110) orientations
Masahisa Takizawa; Takashi Komine; Haruhiko Udono; Tomosuke Aono, Japan Society of Applied Physics
JJAP Conf. Proc., 2020年08月, ［査読有り］

Observation of Magnesium-Induced Crystallization (Mg-MIC) of a-Si Thin Film
Takashi Ikehata; Ryota Sasajima; Motomu Saijo; Naoyuki Sato; Haruhiko Udono, Japan Society of Applied Physics
JJAP Conf. Proc., 2020年08月, ［査読有り］

Semiconducting Silicides Green Technology
Haruhiko UDONO, Institute of Physics Publishing
Japanese Journal of Applied Physics, 2020年04月01日

An Approach to Optimize the Thermoelectric Properties of III–V Ternary InGaSb Crystals by Defect Engineering via Point Defects and Microscale Compositional Segregations
V. Nirmal Kumar; Y. Hayakawa; H. Udono; Y. Inatomi, American Chemical Society (ACS)
Inorg. Chem., 2019年09月03日, ［査読有り］

〔主要な業績〕Origins of the nitrogen-related deep donor center and its preceding species in nitrogen-doped silicon determined by deep-level transient spectroscopy
Nakamura Minoru; Murakami Susumu; Udono Haruhiko, Japan Society of Applied Physics
Applied Physics Express, 2019年02月01日, ［査読有り］

Enhanced thermoelectric properties of InSb: Studies on In/Ga doped GaSb/InSb crystals
V. Nirmal Kumar; Y. Hayakawa; H. Udono; Y. Inatomi, © 2018 Elsevier Ltd In/Ga elements were doped in GaSb/InSb crystals respectively, and their thermoelectric performances were studied. The crystals had cubic zinc blende structure with change in lattice parameters. The charge transfer occurred between all the three (In, Ga and Sb) elements when In was doped with GaSb. Whereas in Ga doped InSb crystals, the charge transfer occurred only among Ga and Sb elements. In/Ga doped GaSb/InSb crystals exhibited degenerate and non-degenerate electrical properties, respectively. Optical modes of phonon vibrations were present, and their transverse mode was dominant over longitudinal mode in all the samples. The thermoelectric figure of merit (ZT) of In doped GaSb crystals were low because of their low power factor and high thermal conductivity. The highest power factor (59.5 μW/cmK2) and ZT (0.56) at 573 K were achieved by Ga doped (1 × 1021/cm3) InSb crystal. The ZT 0.56 at 573 K is thus far the highest among other reported values of InSb crystals.
Intermetallics, 2019年02月01日, ［査読有り］

Evaluation of carrier lifetime in Mg2Si pn-juction photodiode using OCVD method　　　　　　　　　　　　　　　
Haruhiko Udono; Fumiya Takahashi, 筆頭著者
Proceedings of 8th Silicon Forum, 2018年11月19日

Characterization of iron in silicon by low-temperature photoluminescence and deep-level transient spectroscopy
Minoru Nakamura; Susumu Murakami; Haruhiko Udono, We investigate the relationship between the intensity of band-edge (BDE) photoluminescence (PL) from 10 to 70 K and the concentration of iron diffused in boron-doped p-type silicon. Because of the nonradiative recombination activity of the interstitial iron-boron complex (FeiB center), the BDE-PL intensity at each temperature varies distinctively and systematically with the iron concentration, which means that this method has the potential to make the accurate measurements of a wide range of interstitial iron concentrations in silicon. The iron precipitates formed in the bulk and/or at the surface are found to exert much weaker recombination activity for excess carriers than FeiB center by exploiting both PL and deep-level transient spectroscopy (DLTS) measurements. The unexpected enhancement in BDE-PL intensity from iron-diffused silicon between 20 and 50 K is attributed to the passivation of the Si-oxide/Si interface by iron. For the samples diffused with trace amounts of iron, the iron concentration within 20 μm of the surface is significantly greater than that in the bulk, as measured by DLTS. This result is tentatively attributed to the affinity of iron with the Si-oxide., American Institute of Physics Inc.
Journal of Applied Physics, 2018年03月14日, ［査読有り］

Crystal growth of Mg2Si for IR-detector
Toshio Tokairin; Junya Ikeda; Haruhiko Udono, Semiconducting Mg2Si is known as a thermoelectric material and recently attracts increasing attention as a Si-ased, low-cost and environmental friendly material for an infrared (IR) sensor. With the aim of producing cost-fective Mg2Si single crystal substrates for the IR sensor, we have investigated single crystal growth of Mg2Si using the vertical Bridgman (VB) and micro-pulling-down (mu-PD) methods in open-system. Since the evaporation of Mg was not suppressed during the mu-PD, the composition of the Mg2Si single crystal grown by this method was not stoichiometric. On the other hand, single crystalline Mg2Si was produced by the VB method using the Si-treated inner carbon seat and BN-coated carbon crucible. The Mg2Si crystals with a diameter of 30 mm were grown at a growth rate of 0.5 mm/min and a temperature gradient of 5 degrees C/cm. The electron density and mobility of the crystal so obtained were 1.8x10(17) cm(-3) and 283 cm(2)V(-1)s(-1) at 300 K, respectively. The high electron density was due to contamination from the impurities presented in the crucible., ELSEVIER SCIENCE BV
JOURNAL OF CRYSTAL GROWTH, 2017年06月, ［査読有り］

Influence of Humidity, Volume Density, and MgO Impurity on Mg2Si Thermoelectric-Leg
Y. Mito; A. Ogino; S. Konno; H. Udono, We have studied the influence of humidity on the production yield of Mg2Si thermoelectric (TE)-legs synthesized by spark plasma sintering (SPS) and also the influence of sintered density and MgO impurity on the oxidation resistance of the Mg2Si sintered compacts. We observed a strong correlation between the humidity in air atmosphere and the yield rate of Mg2Si TE-legs. The Mg2Si TE-legs sintered from the raw material powder that was exposed to an atmosphere with humidity > 60% contained relatively high density of voids and cracks due to the reaction of adsorbed moisture and Mg2Si during SPS. We found that the Mg2Si sintered density strongly affected the oxidation resistance, whereas a small amount of MgO concentration in the initial sintered compacts had no significant effect on the oxidation resistance. Sb-doped Mg2Si with a high sintered density showed an excellent oxidation resistance in air atmosphere when subjected to an oxidation-resistance test at 600A degrees C for 800 h, which is presumed to be due to the formation of a dense MgO layer on the surface., SPRINGER
JOURNAL OF ELECTRONIC MATERIALS, 2017年05月, ［査読有り］

Optical transmittance and reflectance studies and evidence of weak electron–phonon interaction in Type-I Ge clathrate Ba8Ga16Ge30
Haruhiko Udono; Motoharu Imai; Shuhei Kojima; Tetsuji Kume; Katsumi Tanigaki; Hiroyuki Tajima, The optical properties of ternary type-I Ge clathrate Ba8Ga16Ge30 are investigated by optical reflectance and transmittance measurements. The refractive index and extinction coefficient are calculated from the reflectance spectrum via the modified Kramers-Kronig analysis method between 0.5 and 3.2 eV. The photon energy dependence of the optical absorption coefficient reveals that Ba8Ga16Ge30 is an indirect band gap semiconductor with a gap energy E-g of 0.69 eV at 5.7K and 0.66 eV at 285 K. The temperature dependence of E-g can be satisfactorily described by an equation based on the Bose-Einstein statistics model. When compared with those of common elemental, III-V, and II-VI semiconductors, the small temperature coefficient dE(g)/dT of the Ba8Ga16Ge30 can be considered to represent the weak electron-phonon interaction in the Ba8Ga16Ge30 clathrate. Published by AIP Publishing., AMER INST PHYSICS
J. Appl. Phys., 2017年05月, ［査読有り］

Observation of pn-junction depth in Mg2Si diodes fabricated by short period thermal annealing
Y. Onizawa; T. Akiyama; N. Hori; F. Esaka; Haruhiko Udono
JJAP Conf. Proc., 2017年05月01日, ［査読有り］

Fabrication of Mg2Si pn-junction Photodiode with Shallow Mesa-structure and Ring Electrode
T. Akiyama; N. Hori; S. Tanigawa; D. Tsuya; Haruhiko Udono
JJAP Conf. Proc., 2017年05月01日, ［査読有り］

Oxidation resistance of impurity doped Mg2Si grown from the melt
Shu Konno; Tsubasa Otubo; Kohei Nakano; Haruhiko Udono
JJAP Conf. Proc., 2017年05月01日, ［査読有り］

Preparation and thermoelectric properties of iron disilicide
Isoda, Y.; Udono, H.
Materials, Preparation, and Characterization in Thermoelectrics, 2017年

Effects of varying indium composition on the thermoelectric properties of InxGa1-xSb ternary alloys
V. Nirmal Kumar; M. Arivanandan; T. Koyoma; H. Udono; Y. Inatomi; Y. Hayakawa, InxGa1-xSb (x = 0-1), a III-V ternary alloy, was grown by melt solidification process. The effects of varying indium composition on the thermoelectric properties of InxGa1-xSb polycrystals were studied for the first time. The segregations of indium and gallium elements were observed in the grown crystals, and the defects present in crystals were revealed by etching process. Room-temperature Raman measurement revealed that the dominant optical modes of phonon vibrations in InSb and GaSb binaries were suppressed in InxGa1-xSb ternaries. The in-phase vibrations of acoustic mode phonons were scattered more effectively in InxGa1-xSb by the present defects, and the relative value of lattice thermal conductivity was reduced. Thus, the thermal conductivity of InSb and GaSb binaries was drastically reduced in InxGa1-xSb by alloy scattering. InSb indicated the highest ZT 0.51 because of its higher power factor 70 mu W/cmK(2). Next to InSb, In0.8Ga0.2Sb had higher ZT value of 0.29 at 600 K among the InxGa1-xSb ternaries. The ZT of In0.8Ga0.2Sb was increased about 30 times than that of GaSb by the increase of power factor as well as the decrease of thermal conductivity., SPRINGER
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 2016年10月, ［査読有り］

Thin film of guest-free type-II silicon clathrate on Si(111) wafer
Tetsuji Kume; Fumitaka Ohashi; Kentaro Sakai; Atsuhiko Fukuyama; Motoharu Imai; Haruhiko Udono; Takayuki Ban; Hitoe Habuchi; Hidetoshi Suzuki; Tetsuo Ikari; Shigeo Sasaki; Shuichi Nonomura, Thin films of guest-free type-II Si clathrate (Si-136) were fabricated on Si(111) wafers in two steps: NaxSi136 thin-film formation by thermal decomposition of NaSi precursor films and Na removal from the NaxSi136 film by a heat treatment with iodine. Cross-sectional TEM observation and XRD and Raman measurements verified the formation of 1-mu m-thick Si-136 films on the Si wafer. Since the prepared films showed n-type conduction, pn junction devices were developed by a Si136/p-type Si structure. This device showed a photovoltaic (PV) response under white light illumination. The thin film formation and the PV response of Si136 indicated this Si allotrope to be the next-generation platform for semiconductor technology. (C) 2016 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
THIN SOLID FILMS, 2016年06月, ［査読有り］

X-ray photoelectron spectroscopy studies on single crystalline β-FeSi2
Wei Mao; Haruhiko Udono; Kenji Yamaguchi; Takayuki Terai; Hiroyuki Matsuzaki, In order to realize the photoluminescence of semiconducting beta-FeSi2 homoepitaxial films, surface preparation of single crystalline beta-FeSi2 is of critical importance. An atomically flat and clean substrate surface of beta-FeSi2 was prepared by sputtering with 2 keV Ar+ ions or by heating at 850 degrees C. The structure of the native surface oxide and the removal of this layer were investigated though X-ray photoelectron spectroscopy measurements. No significant deviation of the stoichiometry was detected in the surface region. Our results suggest that a surface prepared in this way is an eligible substrate for homoepitaxy of beta-FeSi2. (C) 2016 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2016年05月, ［査読有り］

Non-destructive depth analysis of the surface oxide layer on Mg2Si with XPS and XAS
Fumitaka Esaka; Takehiro Nojima; Haruhiko Udono; Masaaki Magara; Hiroyuki Yamamoto
Surf. Interface Anal., 2016年02月22日, ［査読有り］

Observation of pn-junction depth in Mg2Si photodiode fabricated by thermal diffusion of Ag acceptor
Haruhiko Udono; Nobuhiko Hori; Tomohiro Akiyama; Yuuma Onizawa; Tsubasa Ootsubo; Fumitaka Esaka, IEEE
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), 2016年, ［査読有り］

Transformation of the nickel donor center by annealing in silicon measured by deep-level transient spectroscopy
Minoru Nakamura; Susumu Murakami; Haruhiko Udono, The concentration changes of nickel-related species after thermal annealing in Schottky electrode-formed (EL-formed) and electrode-free (EL-free) p-type silicon samples diffused with nickel were measured by deep-level transient spectroscopy. The nickel donor center began to decay at approximately 100 degrees C with the activation energies of 1.06 and 0.26 eV for the EL-formed and EL-free samples, respectively, which were analyzed as the required energies for the center to form complexes with interstitial nickel (Ni-i) and hydrogen, respectively. These complexes evolved into extended complexes by further bonding of Nii at higher annealing temperatures. All the complexes above disappeared by evolving into precipitates within temperatures lower than 400 degrees C without recovering the nickel donor center. The transformation reactions of the complexes progressed at lower temperatures and shorter times in the EL-formed samples than in the EL-free samples because of the electric neutralization of the nickel-related species in the space-charge region of the electrode. (C) 2016 The Japan Society of Applied Physics, IOP PUBLISHING LTD
JAPANESE JOURNAL OF APPLIED PHYSICS, 2016年01月, ［査読有り］

Thermal expansion of semiconducting silicides beta-FeSi2 and Mg2Si
Motoharu Imai; Yukihiro Isoda; Haruhiko Udono, The thermal expansion of beta-FeSi2 and Mg2Si was investigated at high temperatures (ranging from 300 to 1173 K for beta-FeSi2 and from 293 to 873 K for Mg2Si) using powder X-ray diffraction. The linear thermal expansion coefficients alpha(L) for the three lattice parameters of beta-FeSi2 range from 10.6(2) to 11.8(4) x 10(-6) K-1, which indicates small anisotropy, which is in contrast to the large anisotropy reported previously. The volumetric thermal expansion coefficient alpha(V) for beta-FeSi2 is relatively large among the transition-metal disilicides. alpha(L) for Mg2Si can be expressed by the linear expression of T: alpha(L) = 11(1) x 10(-6) + 6.9(2) x 10(-9)T K-1. alpha(V) for Mg2Si is larger than that of the transition-metal disilicides, including beta-FeSi2. Based on a comparison of alpha(L) among Mg2Si, several metals and suicides, the candidates for electrode materials are discussed. In particular, temperature dependence and value of alpha(L) for Ni is close to those for Mg2Si, which suggests that Ni is a good candidate electrode material with respect to thermal expansion. (C) 2015 Elsevier Ltd. All rights reserved., ELSEVIER SCI LTD
INTERMETALLICS, 2015年12月, ［査読有り］

Tailoring thermoelectric properties of nanostructured crystal silicon fabricated by infrared femtosecond laser direct writing (vol 212, pg 715, 2015)
Masahiro Mori; Yasuhiko Shimotsuma; Tomoaki Sei; Masaaki Sakakura; Kiyotaka Miura; Haruhiko Udono, Reference [28] is replaced by a corrected citation., WILEY-V C H VERLAG GMBH
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 2015年08月, ［査読有り］

Crystal growth and characterization of Mg2Si for IR-detectors and thermoelectric applications
Haruhiko Udono; Hiroyuki Tajima; Masahito Uchikoshi; Masaru Itakura, We have investigated the melt growth of Mg2Si crystal and its electrical and optical properties. Progress in Mg source purity and stoichiometric control during the growth enabled the development of a high purity Mg2Si crystal with low carrier density and a high stable Mg2Si with good doping controllability. The Mg2Si crystal grown by the pressure controlled Bridgman method using 5N purity or 6N purity of Mg source and purified PG crucible showed low electron density (similar to 10(15)cm(-3)) and high electron mobility (485cm(2)V(-1)s(-1) at 300K and 21900 cm(2)V(-1)s(-1) at 40 K). Silver doping in the high purity crystals performed the low-hole density of p-type Mg2Si (similar to 3 x 10(16)cm(-3)). Ionization energy of residual Al donor in the high purity crystal and Ag acceptor in the Ag doped crystals was determined as 8-9meV and 26meV, respectively. Indirect band gap energy E-g of approximately 0.61 eV at 300K and 0.69 eV at 4K were estimated by the optical transmission measurements on the high purity crystals. It is also found that the Sb-doped melt grown crystal had good power factor around room temperature (26 mu Wcm(-1) K-2 at 270 K). (C) 2015 The Japan Society of Applied Physics, IOP PUBLISHING LTD
JAPANESE JOURNAL OF APPLIED PHYSICS, 2015年07月, ［査読有り］

Characterization of band structure of K8Ga8Si38 clathrate by optical measurement　　　　　　　　　　　　　　　
Masaru Iioka; Haruhiko Udono; Motoharu Imai; Masato Aoki
JJAP Conf. Proc., 2015年06月08日, ［査読有り］

Fabrication and characterization of Mg2Si pn-junction photodiode with a ring electrode　　　　　　　　　　　　　　　
K. Daitoku; M. Takezaki; S. Tanigawa; D. Tsuya; H. Udono
JJAP Conf. Proc., 2015年06月08日, ［査読有り］

Tailoring thermoelectric properties of nanostructured crystal silicon fabricated by infrared femtosecond laser direct writing
Masahiro Mori; Yasuhiko Shimotsuma; Tomoaki Sei; Masaaki Sakakura; Kiyotaka Miura; Haruhiko Udono, The periodic nanostructuring of inner part of semiconductors can be successfully accomplished by the infrared ultrashort pulse laser with a double pulse configuration. Self-organized nanostructures inside semiconductor could be induced empirically only if it is indirect band gap semiconductor. The strained silicon regions with a width of about 100nm are self-aligned parallel to the polarization direction of the first arriving pulses, despite of the polarization direction of the secondly arriving pulses. AFM inspections reveal that such strained silicon nanostructures exhibit high electric conductivity and low thermal conductivity. The formation mechanisms would be interpreted in terms of the electrostrictive force through the interaction between electron-hole plasma and phonon. Apart from the basic understanding, such nanostructured silicon will open the door to the fabrication of the self-contained thermoelectric devices., WILEY-V C H VERLAG GMBH
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 2015年04月, ［査読有り］

Nanostructuring in Indirect Band-gap Semiconductor Using IR Femtosecond Double Pulses
Shimotsuma Yasuhiko; Sei Tomoaki; Sakakura Masaaki; Miura Kiyotaka; Udono Haruhiko
JOURNAL OF LASER MICRO NANOENGINEERING, 2015年01月15日, ［査読有り］

Band structure characterization of KGaSi clathrates by optical measurement
Masaru Iioka; Haruhiko Udono; Motoharu Imai; Masato Aoki
JJAP Conference Proceedings, 2015年, ［査読有り］

Surface aspects of discolouration in Bisphenol A Polycarbonate (BPA-PC), used as lens in LED-based products
M. Yazdan Mehr; W. D. van Driel; H. Udono; G. Q. Zhang, The surface-related reactions during discolouration of Bisphenol A Polycarbonate (BPA-PC), used as LED lens plates, under thermal stress are studied. X-ray photoelectron spectroscopy (XPS) has been used to monitor the changes in the surface chemistry of BPA-PC plates over a temperature range of 100-140 degrees C for a period up to 3000 h. Increasing time under thermal stress is associated with the discolouration, and increase in the yellowing index (YI) of PC plastic lens. The XPS results show that discolouration is associated with oxidation at the surface, finding a significant increase in the signal ratio O-1s/C-1s in the XPS spectra of degraded specimens. During thermal ageing, the C H concentration decreases and new oxide features C=O and O-C=O form, with the latter being a support for oxidation at the surface being a major reaction during discolouration. Results also show that irradiation with blue light during thermal ageing accelerates the kinetics of discolouration and the increased O-1s/C-1s ratio in XPS spectra. (C) 2014 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
OPTICAL MATERIALS, 2014年11月, ［査読有り］

Depth profiles of the nickel donor center in p-type silicon diffused with dilute nickel measured by deep-level transient spectroscopy
Minoru Nakamura; Susumu Murakami; Haruhiko Udono, The depth profiles of the nickel donor center located at E-v + 0.17 eV (E-v: the top energy of the valence band) in p-type silicon diffused with dilute nickel at 525-900 degrees C and slowly cooled to room temperature were measured. Owing to the domination of the fast outdiffusion of nickel, the nickel center concentration at the sample surface was highest for the sample diffused at 525 degrees C, which abruptly decreased, with increasing diffusion temperature. The concentrations of the center in the samples diffused at intermediate temperatures sharply increased with increasing depth and converged to an asymptotic value in the deep region. The concentration fractions of the center of the dissolved nickel in the deep region were 4 to 12% for the samples diffused below 900 degrees C, which were unexpectedly high compared with previous data. A possible formation mechanism of the center through a nitrogen-related defect was discussed. (C) 2014 The Japan Society of Applied Physics, IOP PUBLISHING LTD
JAPANESE JOURNAL OF APPLIED PHYSICS, 2014年09月, ［査読有り］

Thermoelectric Properties of p-Type Mg2Si0.25Sn0.75 Doped with Sodium Acetate and Metallic Sodium
Satoki Tada; Yukihiro Isoda; Haruhiko Udono; Hirofumi Fujiu; Shunji Kumagai; Yoshikazu Shinohara, We have investigated the thermoelectric properties of p-type Na-doped Mg-2 Si0.25Sn0.75 solid solutions prepared by liquid-solid reaction and hot-pressing methods. Na was introduced into Mg2Si0.25Sn0.75 by using either sodium acetate (CH3COONa) or metallic sodium (2 N). The samples doped with sodium acetate consisted of phases with antifluorite structure and a small amount of MgO as revealed by x-ray diffraction, whereas the sample doped with metallic sodium contained the Sn, MgO, and Mg2SiSn phases. The hole concentrations of Mg1.975Na0.025Si0.25Sn0.75 doped by sodium acetate and metallic sodium were 1.84 x 10(25) m(-3) and 1.22 x 10(25) m(-3), respectively, resulting in resistivities of 4.96 x 10(-5) Omega m (sodium acetate) and 1.09 x 10(-5) Omega m (metallic sodium). The Seebeck coefficients were 198 mu V K-1 (sodium acetate) and 241 mu V K-1 (metallic sodium). The figures of merit for Mg1.975Na0.025Si0.25Sn0.75 were 0.40 x 10(-3) K-1 (sodium acetate) and 0.25 x 10(-3) K-1 (metallic sodium) at 400 K. Thus, sodium acetate is a suitable Na dopant for Mg2Si1-x Sn (x) ., SPRINGER
JOURNAL OF ELECTRONIC MATERIALS, 2014年06月, ［査読有り］

Convenient Melt-Growth Method for Thermoelectric Mg2Si
K. Kambe; H. Udono, We have succeeded in growing single-crystalline-like n-type Mg2Si bulk crystals by a convenient melt-growth method that requires no vacuum or inert gas. The Sb-doped, n-type Mg2Si crystals had a density equivalent to the theoretical ideal of 1.99 g cm(3) to 2.00 g cm(-3) and well-developed crystalline grains. Powder x-ray diffraction measurements and scanning electron microscopy observations confirmed the single-phase Mg2Si nature of the grown crystals, with no MgO or unreacted Si and Mg observed. The crystals had high Hall mobility and power factor compared with Sb-doped sintered Mg2Si crystals. The achieved ZT values were 0.10 at 300 K and 0.36 at 600 K for 0.317 at.%Sb-doped Mg2Si., SPRINGER
JOURNAL OF ELECTRONIC MATERIALS, 2014年06月, ［査読有り］

Preparation and thermoelectric properties of Mg2Si0.9-xSnx Ge0.1
S. Tada; Y. Isoda; H. Udono; H. Fujiu; S. Kumagai; Y. Shinohara, We investigated the thermoelectric properties of non-doped Mg2Si0.9-xSnx Ge0.1 (x = 0, 0.60, 0.65, 0.75, and 0.90) solid solutions of quaternary systems prepared using a liquid-solid reaction and hot-pressing methods. All the sintered compact samples consisted of a single phase with an anti-fluorite structure, which was revealed by X-ray diffraction (XRD). The lattice constant increased linearly with increasing amounts of Sn in the sample. Mg2Si0.90Ge0.10 and Mg2Si0.30Sn0.60Ge0.10 exhibited n-type conduction and possessed a negative Seebeck coefficient. On the other hand, Mg2Si0.25Sn0.65Ge0.10, Mg2Si0.15Sn0.75Ge0.10, and Mg2Sn0.90Ge0.10 exhibited positive conduction. The resistivities ranged from 3.22 × 10-5 Ω m for Mg2Si0.90Ge0.10 to 1.37 × 10-2 Ω m for Mg2Si0.30Sn0.60Ge0.10 at 300 K. The thermal conductivity varied depending on the amount of Sn in the samples. The minimum value of the thermal conductivity was 1.93 W m-1 K-1 for Mg2Si0.30Sn0.60Ge0.10 and Mg2Si0.25Sn0.65Ge0.10 at 450 K. © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Physica Status Solidi (C) Current Topics in Solid State Physics, 2013年12月, ［査読有り］

Solid-phase growth of Mg2Si by annealing in inert gas atmosphere
Takashi Ikehata; Tatsuya Ando; Takuya Yamamoto; Yuta Takagi; Naoyuki Sato; Haruhiko Udono, Magnesium silicide (Mg2Si) is an attractive semiconductor material for application to thermo-electric conversion devices because it consists of non-toxic and resource-abundant elements. There were difficulties, however, in preparation of Mg2Si thin films coming from large difference in thermodynamic properties between Mg and Si. In the present study, preparation of Mg2Si thin films by solid-phase synthesis
thermal annealing of metallic Mg on a Si substrate in argon gas atmosphere, is tested and optimum annealing conditions for the synthesis are explored. As a result, it is found that the optimum annealing temperature is 300-350 °C and the argon gas pressure should be higher than 50 Pa. © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Physica Status Solidi (C) Current Topics in Solid State Physics, 2013年12月, ［査読有り］

Solution growth and optical characterization of Mn11Si19
Masaru Iioka; Daisuke Ishida; Shyuhei Kojima; Haruhiko Udono, We have investigated the optical property of single-phase Mn11Si19 bulk crystals grown by the temperature gradient solution growth (TGSG) method using Ga solvent. The optical absorption spectrum near the fundamental absorption edge was evaluated by transmission and reflectance measurements between 5 K and 300 K. Optical constants of refractive index n and extinction coefficient k were determined from normal reflectance spectrum by Kramers-Kronig analysis. The value of n was 5-6 near the band edge energy. From the relation of the optical absorption spectra to photon energy, we found that Mn11Si19 has indirect band gap structure with the absorption edge energy of approximately 0.64 eV at 5 K. © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Physica Status Solidi (C) Current Topics in Solid State Physics, 2013年12月, ［査読有り］

Solid evidence for magnetic moment enhancement in micro-particles of Mn11Si19
Kiyotaka Hammura; Haruhiko Udono; Tomosuke Aono, We study magnetic properties of Mn11Si19 both in a bulk and in a powder (the averaged diameter of particles was about 5 μm) states. The bulk sample was grown using the temperature gradient solution method, and the powder sample was obtained through pounding the bulk sample in a mortar. We measured magnetisation as a function of temperature using a SQUID magnetometer. We found that the bulk sample was paramagnetic while the power sample was soft ferromagnetic. The magni- tude of the magnetisation of the powder sample was al- most unchanged between5K to 300 K. © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Physica Status Solidi (C) Current Topics in Solid State Physics, 2013年12月, ［査読有り］

Spectral characterization of Mg2Si pn-junction diode depended on RTA periods
M. Takezaki; Y. Yamanaka; M. Uchikoshi; H. Udono, We have studied the effect of thermal annealing periods on the optoelectrical properties of Mg2Si pn -junction diodes fabricated by a conventional thermal diffusion process of Ag acceptor. The Au/Ag/n -Mg2Si (carrier concentration = 2 × 1015cm-3, resistivity = 5-10 Ωcm) substrate was annealed at 550 °C in the Ar-atmosphere using a rapid thermal annealing (RTA) furnace. The annealing periods were varied between 2 and 10 minutes. Clear rectifying behavior of J -V characteristics was observed for the diodes annealed for more than 2 minutes. Spectral responsivity from the photon energy threshold of approximately 0.6 eV was demonstrated with the Mg2Si pn -junction diodes under the zero bias condition at room temperature. The maximum intensity of spectral responsivity was increased with decrease the annealing period. The spectral responsivity of the diode with the RTA periods of 4 minutes was approximately 4 times higher than that of 10 minutes annealed one. (© 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim) © 2013 WILEY-VCH Verlag GmbH &
Co. KGaA, Weinheim.
Physica Status Solidi C, 2013年11月13日, ［査読有り］

Energy level(s) of the dissociation product of the 1.014 eV photoluminescence copper center in n-type silicon determined by photoluminescence and deep-level transient spectroscopy
Minoru Nakamura; Susumu Murakami; Haruhiko Udono, The annealing behavior of copper centers in n-type silicon diffused with dilute copper was measured by photoluminescence (PL) and deep-level transient spectroscopy (DLTS) to investigate the energy level (or levels) of the dissociation product center of the 1.014 eV PL copper center. Among several DLTS peaks that appeared by the annealing, only the energy level at E-c - 0.16 eV (E-c: bottom energy of the conduction band) was suggested as the double acceptor level of the dissociation product center. From the disagreement between the measured energy levels of the dissociation product center and the estimated acceptor levels of substitutional copper (Cu-s), Cu-s was judged to be inappropriate for the origin of the product center. (C) 2013 AIP Publishing LLC., AMER INST PHYSICS
JOURNAL OF APPLIED PHYSICS, 2013年07月, ［査読有り］

シリサイド半導体の結晶成長とデバイス応用
鵜殿 治彦, 豊富な資源量の元素で構成されるシリサイド半導体は、材料を大量消費するエネルギー利用の分野において資源・環境リスクの面から優れたポテンシャルを秘めている。本稿では、我々が進めてきたβ-FeSi_2とMg_2Siの結晶成長技術と基本的な電気・光学特性、および熱電変換や熱光発電,赤外センサを目指したデバイス開発動向について紹介する。, 一般社団法人電子情報通信学会
電子情報通信学会技術研究報告. ED, 電子デバイス, 2013年05月09日, ［査読有り］

Infrared photoresponse from pn-junction Mg2Si diodes fabricated by thermal diffusion
Haruhiko Udono; Yusuke Yamanaka; Masahito Uchikoshi; Minoru Isshiki, We fabricated pn-junction diodes by thermal diffusion of Ag acceptor into n-type melt-grown Mg2Si single-crystalline substrates (electron concentration=2×1015 cm-3) to investigate the infrared photoresponse of the material. The estimated hole concentration at the p-side of the diode diffused with Ag at 550 °C was 3×1018 cm-3. Current-voltage measurement of the diodes showed sound rectifying characteristics even at 300 K. A clear photoresponsivity with a photon energy threshold of approximately 0.6 eV was observed from the diode, showing promise for application in infrared light detection devices at wavelengths of 1.2-2 μm. © 2012 Elsevier Ltd. All rights reserved.
Journal of Physics and Chemistry of Solids, 2013年02月, ［査読有り］

Thermoelectric properties of Na-doped Mg2Si0.25Sn0.75
S. Tada; Y. Isoda; H. Udono; H. Fujiu; S. Kumagai; Y. Shinohara, We have investigated the thermoelectric properties of Na-doped Mg₂Si_0.25Sn_0.75 solid solutions prepared by liquid-solid reaction and hot-pressing methods. Na doping was carried out by mixing sodium acetate (CH₃COONa) into the starting materials Mg (nominal purity: 99.9 %), Sn (99.999 %) granules, and Si powder (99.9999 %). The Na-doped samples had p-type conductivity with positive signs of Seebeck and Hall coefficients. Furthermore, hole concentrations increased rapidly with an increase in the amount of Na doping. These results revealed that the Na atoms acted as acceptors in Mg₂Si_0.25Sn_0.75. The Seebeck coefficient of Na-doped samples showed positive values between 300 and 750 K. A maximum power factor of 0.88 × 10^-3 WmK^-2 was observed for the Mg₂Na_0.020Si_0.25Sn_0.75 sample at 500 K. The dimensionless figure of merit ZT reached 0.17 at 450 K for all Na-doped samples., The Materials Research Society of Japan
Trans. Mat. Res. Soc. Jpn., 2013年01月07日, ［査読有り］

Transformation reactions of copper centers in the space-charge region of a copper-diffused silicon crystal measured by deep-level transient spectroscopy
Minoru Nakamura; Susumu Murakami; and Haruhiko Udono, The transformation reactions of copper centers by annealing in Schottky electrode-formed (EL-formed) silicon crystals diffused with copper were measured by deep-level transient spectroscopy (DLTS) and the results were compared with those measured in samples without electrode (EL-free). The dissociation speeds of the dominant center (denoted as the Cu-DLB center) to the dissociation product (denoted as the Cu-DLA center) in the EL-formed samples were more than two orders faster than those in EL-free samples at respective annealing temperatures, although the dissociation energy of the former center was identical in both samples. An extended copper center, which was never observed in EL-free samples, was formed in the EL-formed samples at the cost of the Cu-DLA center. The origins of these specialties in the EL-formed samples were attributed to the actions of the electric field on the copper species in the space-charge region of the samples. The easy dissociation of the Cu-DLA center in the EL-formed samples was explained by the change in the charge state of the center in the space-charge region of the samples. From this analysis, the positively charged copper bonded at the bond center (Cu-BC(+)) was proposed as the most probable model for the Cu-DLA center. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754862], AMER INST PHYSICS
Journal of Applied Physics, 2012年09月27日, ［査読有り］

Copper centers in copper-diffused n-type silicon measured by photoluminescence and deep-level transient spectroscopy
Minoru Nakamura; Susumu Murakami; and Haruhiko Udono, While photoluminescence observed the continuous change of the 1.014-eV copper center (CuPL center) intensity with diffusion temperature, deep-level transient spectroscopy (DLTS) measured a considerable number of independent copper-related peaks in silicon samples copper-diffused at different temperatures. There was no DLTS peak whose intensity showed the same diffusion-temperature dependence as that of the CuPL center intensity, which led the conclusion that the CuPL center has no electrically active energy level in the upper-half of the band-gap in silicon. All the DLTS peaks observed were attributed to originate from the variety of copper clusters or small copper precipitates. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4739470], AMER INST PHYSICS
Applied Physics Letters, 2012年07月27日, ［査読有り］

Growth condition dependence of direct bandgap in β-FeSi2 epitaxial films grown by molecular beam epitaxy
K. Noda; Y. Terai; N. Miura; H. Udono; Y. Fujiwara, Direct bandgap energy (E-g) and lattice deformations were investigated in beta-FeSi2 epitaxial films grown by molecular beam epitaxy (MBE) with different growth condition. As Si/Fe flux ratio during the MBE growth became smaller than Si/Fe = 2.0, the lattice constants deviated from those of beta-FeSi2 single crystal, which indicated an enhanced lattice deformation at the lower Si/Fe ratio. In photoreflectance (PR) measurements, the PR spectra shifted to lower photon energy with the enhanced lattice deformation. These results revealed that the Eg of beta-FeSi2 epitaxial film was modified by the lattice deformation depending on the growth condition. (C) 2011 Published by Elsevier B.V Selection and/or peer-review under responsibility of Publication Committee of ASCO-NANOMAT 2011 and Far Eastern Federal University (FEFU), ELSEVIER SCIENCE BV
Physica Procedia, 2012年02月, ［査読有り］

Growth condition dependence of direct bandgap in β-FeSi2 epitaxial films grown by molecular beam epitaxy
K. Noda; Y. Terai; N. Miura; H. Udono; Y. Fujiwara, Direct bandgap energy (Eg) and lattice deformations were investigated in β-FeSi2 epitaxial films grown by molecular beam epitaxy (MBE) with different growth condition. As Si/Fe flux ratio during the MBE growth became smaller than Si/Fe = 2.0, the lattice constants deviated from those of β-FeSi2 single crystal, which indicated an enhanced lattice deformation at the lower Si/Fe ratio. In photoreflectance (PR) measurements, the PR spectra shifted to lower photon energy with the enhanced lattice deformation. These results revealed that the Eg of β-FeSi2 epitaxial film was modified by the lattice deformation depending on the growth condition.
Physics Procedia, 2012年, ［査読有り］

Bandgap modifications by lattice deformations in beta-FeSi2 epitaxial films
Y. Terai; K. Noda; K. Yoneda; H. Udono; Y. Maeda; Y. Fujiwara, The modifications of direct transition energies by lattice deformations were investigated in beta-FeSi2 epitaxial films, polycrystal films and single crystal, systematically. The lattice deformations depending on thermal annealing temperature (T-a) were observed in beta-FeSi2 epitaxial films. In photoreflectance (PR) measurements, the direct transition energies of the epitaxial films shifted to lower energies as the Ta increased. The polycrystal films did not show the lattice deformation and the shift of direct transition energies. These results show that the direct bandgap is modified by the lattice deformation originating from the lattice mismatch at the hetero-interface of beta-FeSi2/Si. (C) 2011 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE SA
THIN SOLID FILMS, 2011年10月, ［査読有り］

Band-gap Modifications of β-FeSi2 Epitaxial Films by Lattice Deformations　　　　　　　　　　　　　　　
Y. Terai; K. Noda; K. Yoneda; H. Udono; Y. Maeda; Y. Fujiwara
Thin Solid Films, 2011年10月, ［査読有り］

Magnetisation of bulk Mn11Si19 and Mn4Si7
K. Hammura; H. Udono; I. J. Ohsugi; T. Aono; E. De Ranieri, The purpose of this paper is to determine by experiment whether Mn11Si19 and Mn4Si7 in their bulk states have a finite magnetic moment or not. Magnetisation measurements were carried out on these materials using both SQUID system and Kerr rotation system. The high quality samples were grown using the temperature gradient solution growth method. SQUID measurements revealed that Mn11Si19 has finite magnetism while Mn4Si7 does not in their bulk states. It was also confirmed that Mn4Si7 became magnetic and Mn11Si19 got to exhibit a distinctive hysteresis in their powdery state. The enhancement of magnetism implied that the surface of the samples was to a great extent linked to its magnetism. (C) 2011 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2011年10月, ［査読有り］

Solution Growth and Thermoelectric Properties of Single-Phase MnSi1.75−x
H. Udono; K. Nakamori; Y. Takahashi; Y. Ujiie; I. J. Ohsugi; T. Iida
J. Electron. Mat., 2011年07月, ［査読有り］

Photoemission study on the valence band of a ß-FeSi2 thin film using synchrotron radiation
H Fujimoto; K. Ogawa; K. Takarabe; H. Udono; H. Sugiyama; J. Azuma; K. Takahashi; M. Kamada, Resonant and constant-initial state photoemission spectroscopies using synchrotron radiation were applied to investigate the valence-band electronic structure of a semi-conducting beta-type iron-disilicide (beta-FeSi2) thin film. The results clearly indicated that the component elements, iron (Fe) and silicon (Si), contribute differently to the valence band features; the Fe 3d orbitals mainly concentrate in the top region of the valence band while the Si 3s and 3p orbitals spread over the wide region of the valence band. The beta-FeSi2 thin film showed a typical p-type semi-conducting nature with a work function of 4.78 eV. The beta-FeSi2 film showed the Fe M1VV Auger lines around the kinetic energy of 88 eV. It would be expected from these observations that there exist strong interactions between iron and silicon atoms in the beta-FeSi2 film resulting in orbital mixing and band formation., ROYAL SOC CHEMISTRY
Dalton Trans., 2011年07月, ［査読有り］

Semiconducting behavior of type-I Si clathrate K8Ga8Si38
M. Imai; A. Sato; H. Udono; Y. Imai; H. Tajima, A ternary type-I Si clathrate K8Ga8Si38 has been revealed to be an indirect band gap semiconducting material with an energy gap (E-g) of approximately 0.10 eV, which is much smaller than the calculated E-g value that is 0.15 eV wider than E-g of elemental Si with the diamond-type structure., ROYAL SOC CHEMISTRY
Dalton Trans., 2011年05月, ［査読有り］

Surface analysis of single-crystalline β-FeSi2
Y. Yamada; W. Mao; H. Asaoka; H. Yamamoto; F. Esaka; H. Udono; T. Tsuru, Clean surfaces of the single crystalline beta-FeSi2 have been prepared and investigated by means of surface analysis techniques. X-ray photoelectron spectroscopy of the surface oxide reveals that the surface Si is mainly oxidized while Fe isn't. After removing the surface oxide, clean surface can be obtained showing well-defined atomic features in low-energy electron diffraction and scanning tunneling microscopy. No drastic surface reconstruction is found possibly reflecting strong Fe-Si bond. Density functional theory calculation suggests the spin polarized surface electronic density of states when Fe comes at the surface, although such a situation seems to be unlikely. (C) 2010 Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physica Procedia, 2011年01月, ［査読有り］

Electrical Properties of Ca2Si Sintered Compact Synthesized by Spark Plasma Sintering
C. Wen; T. Nonomura; A. Kato; Y. Kenichi; H. Udono; K. Isobe; M. Otake; Y.Kubota; T. Nakamura; Y. Hayakawa; and H. Tatsuoka, Single-phase orthorhombic Ca2Si sintered compacts were synthesized by the spark plasma sintering technique. The electronic structures and Seebeck coefficient of Ca2Si were calculated using the first-principles total-energy calculation program. It was found that the Ca2Si compact showed a p-type conductivity of similar to 10(-2) S/cm with an activation energy of 0.13 eV, and the experimental Seebeck coefficient is larger than 250 mu V/K from 373K to 573K. (C) 2010 Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physica Procedia, 2011年01月, ［査読有り］

Surface characterization of homoepitaxial β-FeSi2 film on β-FeSi2 (111) substrate by X-ray photoelectron and absorption spectroscopy
F. Esaka; H. Yamamoto; H. Udono; N. Matsubayashi; K. Yamaguchi; S. Shamoto; M. Magara; T. Kimura, Surface characterization of a homoepitaxial beta-FeSi2 film grown on a beta-FeSi2 single crystal synthesized with a temperature-gradient solution method was performed by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The annealing to remove native oxide layers on the crystal before homoepitaxial growth induced the formation of Fe-rich silicide in the surface. The XAS spectra confirm that the homoepitaxial beta-FeSi2 film can be grown on the crystal, while Fe-rich silicide is partially formed. The control of the surface chemical state is important to obtain homoepitaxial films with excellent quality. (C) 2010 Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physica Procedia, 2011年01月, ［査読有り］

Preparation of schottky contacts on n-type Mg2Si single crystalline substrate
K.Sekino; M.Midonoya; H. Udono; Y. Yamada, We have studied metal-semiconductor contact of n-type Mg2Si single crystal grown by the Bridgman method. We found that a contact of Ag/n-Mg2Si showed ohmic property whereas a contact of Au/n-Mg2Si performed Schottky property. Mesa structure at the Au/n-Mg2Si contact, which was formed by etching with diluted HF (2%) solution and Au-metal mask, successfully improved the leakage current in reverse bias region. The Shottky barrier height phi(B) = 0.59eV was obtained from the J-V characteristics of the mesa structured Au/n-Mg2Si/Ag contacts. (C) 2010 Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physica Procedia, 2011年01月, ［査読有り］

Surface structures of β-FeSi2 formed by heat-treatment in ultra-high vacuum and their influence on homoepitaxial growth
S. Matsumura; K. Ochiai; H. Udono; F. Esaka; K. Yamaguchi; H. Yamamoto; K. Houjo, We have studied the surface structures of single crystalline beta-FeSi2 substrate and their influence on homoepitaxial growth. After heat-treatment in ultra-high vacuum above 750 degrees C, where the native oxide layer (SiOx) on the substrate was removed, characteristic structures depending on the surface orientation were formed on the substrate. On the beta-FeSi2 (100) substrate, the round shaped dip structures with conical elevation appeared after heat treatment above 800 degrees C. The composition of the dip structures was partially Fe-rich as compared with nominal beta-FeSi2 composition (Si/Fe=2). These characteristic structures significantly affected the crystalline quality. They remained in the epitaxial layer after thin film growth. We also achieved homoepitaxial beta-FeSi2 films on beta-FeSi2 (111) substrate at the growth temperature of 700 degrees C and 800 degrees C. (C) 2010 Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physica Procedia, 2011年01月, ［査読有り］

Spectroscopic characterization of β-FeSi2 single crystals and homoepitaxial β-FeSi2 films by XPS and XAS
F. Esaka; H. Yamamoto; H. Udono; N. Matsubayashi; K. Yamaguchi; S. Shamoto; M. Magara; T. Kimura, Chemical state analysis by a combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) using synchrotron radiation is performed for beta-FeSi2 single crystals and homoepitaxial beta-FeSi2 films. The Si 2p XPS and Fe L-edge XAS spectra imply that the annealing at 1173 K to remove native oxide layers on the crystal induces the formation of FeSi in the surface. The formation of FeSi is also confirmed by Si K-edge XAS analysis. For the homoepitaxial beta-FeSi2 films grown on the crystals, the Si K-edge XAS spectra indicate that structurally homogeneous beta-FeSi2 films can be grown on the beta-FeSi2 single crystals when the substrate temperatures of 973 and 1073 K are applied for molecular beam epitaxy (MBE). Consequently, it is indicated that the combination of XPS and XAS using synchrotron radiation is a useful tool to clarify chemical states of beta-FeSi2 single crystals and homoepitaxial beta-FeSi2 films, which is important to reveal optimized growth conditions of homoepitaxial films. (C) 2010 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Appl. Surf. Sci., 2011年01月, ［査読有り］

Effect of temperature modulation during temperature gradient solution growth of β-FeSi2
Y. Ujiie; K. Nakamori; S. Mashiko; H. Udono; T. Nagata, We have grown beta-FeSi2 single crystals by the temperature modulated TGSG method using Ga solvent and Fe0.98Co0.02Si2 solute to observe the solution growth process. Growth striations corresponded to the temperature modulation cycles were clearly observed in the beta-FeSi2 crystals grown using Fe0.98Co0.02Si2 solute, whereas they were not observed in the crystals grown using FeSi2 solute. SEM-EDX measurements revealed the striation was caused by the fluctuation of Co impurity. From the observation of striations, we found that the growth mechanism of beta-FeSi2 would be explained by the constant growth rate model and also the growth rates along < 011 > and < 010 > directions were larger than that of < 001 > direction. (C) 2010 Published by Elsevier B.V., ELSEVIER SCIENCE BV
Physica Procedia, 2011年01月, ［査読有り］

The local structure of α-FeSi2 under high pressure
Y.Mori; H. Nakano; G. Sakane; G. Aquilanti; H. Udono; K. Takarabe
phys. stat. sol. (b), 2009年05月, ［査読有り］

Surface preparation and characterization of single crystalline β-FeSi2
Y. Yamada; I. Wakaya; S. Ohuchi; H. Yamamoto; H. Asaoka; S. Shamoto; H. Udono, Well-defined clean surfaces of single crystalline beta-FeSi2 have for the first time been prepared and characterized at the atomic scale. Surface oxide was removed by heating the crystal at 850 degrees C in ultra-high vacuum (UHV), resulted in an atomically flat, clean surface. Scanning tunneling microscope (STM) and low-energy electron diffraction (LEED) measurements reveal the absence of long-range surface reconstruction in the low-index (100), (101) and (110) surfaces, which is unique among compound semiconductors. However, a significant number of surface defects could still be found within the clean surface. Characterizing and controlling of those surface defects will be necessary in order to use this material in applications. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Surface Science, 2008年09月, ［査読有り］

Crystal growth of ZnO bulk by CVT method using PVA
H. Udono; Y. Sumi; S. Yamada; I. Kikuma, Seeded crystal growth of Zinc oxide (ZnO) by the closed ampoule chemical vapor transport (CVT) is carried out using polyvinyl alcohol (PVA) as a transport agent. Under the conditions of T-S = 1100 degrees C, Delta T = 10 K and the amount of PVA = 0.13-0.91 mg/cm(3), single-crystalline ZnO was grown continuously on the ZnO seed-crystal, of which the surface was (0001) Zn-face. The grown crystals had well-marked growth facets belonged to {10 (1) over bar0} and {10 (1) over bar1} faces. The color of the crystals was changed from pale yellow to dark orange-red depending on the amount of PVA. Typical electron density and the Hall mobility of the crystals were I X 10, 7 cm(-3) and 2 x 10(2) cm(2)/Vs at 300 K, respectively. (c) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF CRYSTAL GROWTH, 2008年04月, ［査読有り］

Solution Growth and Low-Temperature Thermoelectric Properties of Single Crystalline ß-FeSi2
H. Udonoa; H. Suzuki; K. Goto; S. Mashiko; M. Uchikoshi; M. Issiki, We have measured the Seebeck coefficient and power factor of single crystalline beta-FeSi2 grown by a temperature gradient solution growth (TGSG) method using Ga and Zn solvent. Typical resistivity and carrier density at 300K were 0.03 Omega cm and 2 x 10(19) cm(-3) for p-type and 0.2 Omega cm and 5 x 10(18) cm(-3) for n-type crystals, respectively. The Seebeck coefficient measured along [011] direction was approximately 350 mu V/K(p-type) and -700 mu V/K(n-type) at 300K and showed a maximum value of 500 mu V/K(p-type, T=similar to 25K) and 2100 mu V/K(n-type, T=similar to 70K). The maximum power factor was 4.2 x 10(-6) Wcm(-1)K(-2) (p-type, T=170K) and 23 x 10(-6) Wcm(-1)K(-2) (n-type, T=100K). The value was more than one order of magnitude larger than that of previously reported., IEEE
Proceedings of Int. Conf. Thermoelectrics, 2008年04月

Local neutron transmutation doping using isotopically enriched silicon film
Yoichi Yamada; Hiroyuki Yamamoto; Hironori Ohba; Masato Sasase; Fumitaka Esaka; Kenji Yamaguchi; Haruhiko Udono; Shin-Ichi Shamoto; Atsushi Yokoyama; Kilchi Hojou, By means of thermal neutron irradiation on nanostructure fabricated from Si-30-enriched material, the nanoregion can be selectively and homogeneously doped with (31)p owing to the nuclear transmutation of Si-30 -> 31p (local neutron transmutation doping, NTD). In order to demonstrate the capability of local NTD, Si-30-enriched silicon film is fabricated on p-Si(1 0 0) and irradiated by thermal neutrons. Upon the irradiation, film is n-doped while the substrate remains p-type, resulting in a formation of a p-n junction at film-substrate interface showing a rectification. This suggests strong possibility for application of the NTD for nano-scaled semiconductor devices. (c) 2007 Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 2007年11月, ［査読有り］

Polarized optical reflection study on single crystalline beta-FeSi2
Haruhiko Udono; Isao Kikuma; Hiroyuki Tajima; Kenichi Takarabe, Polarized optical reflectance of single crystalline beta-FeSi2 has been investigated up to 3.1 eV for the light polarization of E//a, E//b and E//c. We observed the clear anisotropy in the spectrums of reflectance, refractive index n, extinction coefficient k and dielectric function epsilon, depending on the light polarizations. From the comparison with the experiments and the theoretical calculation, we found that features of those experimental spectrums agrees well with the theoretical ones calculated by the full potential linear augmented plane wave method based on the density functional theory and the dipole approximation. The anisotropy of n was found to be 10-20% between 1 eV and 3.1 eV, while it was small (<similar to 5%) below 1 eV., SPRINGER
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, 2007年10月, ［査読有り］

Growth of β-FeSi2 thin films on β-FeSi2 (110) substrates by molecular beam epitaxy
M. Muroga; H. Suzuki; H. Udono; I. Kikuma; A. Zhuravlev; K. Yamaguchi; H. Yamamoto; T. Terai, We have investigated the preparation of beta-FeSi2 substrate and growth condition of beta-FeSi2 thin film on beta-FeSi2 (110) substrate by molecular beam epitaxy. The surface of the substrate was prepared by a wet-etching using HF(50%):HNO3(60%):H2O = 1:1:5 solution at 25 degrees C. It is clear that the optimal etching period to obtain a flat surface was 3 min. The beta-FeSi2 thin film with streak RHEED pattern was obtained at Si/Fe flux ratio of 2.9. Average surface roughness (Ra) of the beta-FeSi2 film was about 0.5 nm in 5 x 5 mu m(2) area. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2007年08月, ［査読有り］

Preparation of β-FeSi2 substrates by molten salt method
M. Okubo; T. Ohishi; A. Mishina; I. Yamauchi; H. Udono; T. Suemasu; T. Matsuyama; H. Tatsuoka, Large-sized beta-FeSi2 substrates were successfully prepared for the first time from the silicide bulk crystal grown by the molten salt method. The structural, electrical and optical properties of the as-grown beta-FeSi2 bulk crystals were also investigated. The crystal is single phase beta-FeSi2, and polycrystalline with no preferable growth crystallographic orientations. It was also determined that the beta-FeSi2 shows a p-type conduction, and the hole concentration and the Hall mobility at room temperature were about 10(17) cm(-3) and 10 cm(2)-Vs, respectively. In addition, the PL emission around 0.8 eV was realized from the beta-FeSi2 bulk crystal. This simple vacuum-free growth technique of beta-FeSi2 and the large-sized substrate preparation procedure encourage us to develop future silicide-based electronics. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2007年08月, ［査読有り］

Melt growth and characterization of Mg2Si bulk crystals
Daiki Tamura; Ryo Nagai; Kazuhiro Sugimoto; Haruhiko Udono; Isao Kikuma; Hiroyuki Tajima; Isao J. Ohsugi, We have grown Mg2Si bulk crystals by the vertical Bridgman method using a high-purity Mg (6N-up) source. The grown crystals were single-phase Mg2Si and had well-developed grains (1-5 mm(3)). Lane observations and SEM-EDX observations confirmed that crystalline quality in the grains was single crystal with stoichiometric composition. Electron concentration of the single crystalline specimens grown from 6N-up-Mg was 4.0 x 10(15) cm(-3) at room temperature (RT). This value is more than one order of magnitude lower than that of specimens grown from 4N-Mg [ (5-7) x 10(16) cm(-3)]. The Hall mobility of 14,500 cm(2)/Vs was observed at 45 K in the crystals grown from 6N-up-Mg. We also found that Al impurity plays an important role in the crystals grown from a low-purity Mg source. From the optical absorption measurement, we estimated that the indirect energy gap was about 0.66 eV at 300 K and about 0.74 eV at 4 K. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
THIN SOLID FILMS, 2007年08月, ［査読有り］

Single crystalline β-FeSi2 grown using high-purity FeSi2 source
Kouhei Gotoh; Hirokazu Suzuki; Haruhiko Udono; Isao Kikuma; Fumitaka Esaka; Masahito Uchikoshi; Minoru Isshiki, We have investigated the effect of FcSi(2) source purity on the electrical property of beta-FeSi2 grown from solution. A high-purity FeSi2 source avoided a contamination of Cu and W metals was synthesized by melting a high-purity Fe (5N) and Si (5N-up) in a quartz ampoule. Glow discharge mass spectrometry revealed that the purity of the FeSi2 source synthesized using 5N-Fe and a quartz-ampoule-melting process is one order of magnitude higher than that of the conventional arc-melted FeSi2 source using 4N-Fe. The beta-FeSi2 crystals grown using the bigh-purity FeSi2 and Zn solvent showed n-type conduction, whereas those grown using the are-melted FeSi2 showed p-type. The carrier concentration of the n-type crystals was (4.9-6.3) x 10(18) cm(-3), which was more than 10 times higher than that of the p-type crystals (5.2 x 10(17) cm(-3)). From the ICPMS and SIMS analysis of the grown crystals, we found that dominant impurity concentrations (Cr, Mn, Co, Ni, Cu, Zn and W) in the p-type crystals were higher than those in the n-type ones. Therefore, the p-type conductivity of undoped crystals grown using Zn solvent results from unintentional doping by the high impurity level of the used FeSi2 source. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2007年08月, ［査読有り］

Novel photo-sensitive materials for hydrogen generation through photovoltaic electricity
Kenji Yamaguchi; Haruhiko Udono
International Journal of Hydrogen Energy, 2007年01月03日, ［査読有り］

Thermoeletric properties of solution grown β-FeSi2 single crystals
Hirokazu Suzuki; Haruhiko Udono; Isao Kikuma, We have measured the Seebeck coefficient of single crystalline beta-FeSi2 grown by a temperature gradient solution growth (TGSG) method using Ga solvent. Rectangular-like beta-FeSi2 plates with the size of (3-6) x (1-2) x 0.3 mm(3), where the longitudinal axis was [011], were prepared from the grown ingots. Typical resistivity and hole concentration of the crystals were 4 x 10(-4) Omega m and 2 x 10(25) m(-3) at room temperature (RT), respectively. The Seebeck coefficient measured along the [011] direction was approximately 350 mu V/K at RT and showed the maximum value of 500 mu V/K between 20 and 25 K. We also found that the solution grown single crystals had large power factors below RT. The value was 3.4 x 10(-4) Wm(-1) K-2 at RT, which was about three times larger than that of sintered poly-crystals and CVT-grown single crystals. The maximum power factor was 4.5 x 10(-4) Wm(-1) K-2 around 150 K. The value was more than one order of magnitude larger than reported values., JAPAN INST METALS
Mater. Trans., 2006年06月15日, ［査読有り］

Solution growth of n-type β-FeSi2 single crystals using Ni-doped Zn solvent
H. Udono; Y. Aoki; H. Suzuki; I. Kikuma
J. Crystal Growth, 2006年05月24日, ［査読有り］

Effect of thermal annealing on the photoluminescence of β-FeSi2 films on Si substrate
Kenji Yamaguchi; Kenichiro Shimura; Haruhiko Udono; Masato Sasase; Hiroyuki Yamamoto; Shin-ichi Shamoto; Kiichi Hojou
Thin Solid Films, 2005年11月23日

High interband transitions in β-FeSi2 under pressure
Yasunobu SUMIDA; Yoshihisa MORI; Kenichi TAKARABE; Haruhiko UDONO; Isao KIKUMA, The effect of pressure on high interband transitions up to 3 eV in beta-FeSi2 is studied by measuring reflectivity spectra up to 16 GPa. The evaluated linear pressure coefficients for the interband transitions are all positive and about 8 meV/GPa for the transitions below 1.6eV and about 16meV/GPa for those beyond 1.6eV. The previously determined pressure coefficient of the direct absorption edge (0.875 eV) is 15.9 meV/GPa. This characteristic indicates that the density of states near the energy gap consists of two different bands, with large- and small-pressure coefficients., JAPAN SOC APPLIED PHYSICS
Jpn. J. Appl. Phys., 2005年10月11日, ［査読有り］

Growth and characterization of Mg2Si bulk crystals　　　　　　　　　　　　　　　
Haruhiko Udono; Ryo Nagai; Daiki Tamura; Isao Kikuma
The 3rd Asian Conference on Crystal Growth and Crystal Technology, Beijin China, 2005年10月

Solution growth of N-type β-FeSi2 single crystals using Sn-solvent
Haruhiko Udono; Kazutaka Matsumura; Isao J. Osugi; Isao Kikuma
J. Crystal Growth, 2004年12月15日, ［査読有り］

Solution Growth of high quality p-type β-FeSi2 single crystals using Zn solvent
Hauruhiko Udono; Yuta Aoki; Isao Kikuma; Hiroyuki Tajima; Isao J. Ohsugi
J. Crystal Growth, 2004年12月15日, ［査読有り］

Structural study of FeSi2 under pressure
K. Takarabe; T. Ikai; Y. Mori; H. Udono; I. Kikuma, The structural properties of beta- and alpha-FeSi2 were examined by high-pressure x-ray diffraction at room temperature. In beta-FeSi2, the lattice compression in the longest a axis is larger than in the b and c axes. The expected pressure-induced quenching by the Jahn-Teller effect on gamma-FeSi2 was not achieved in the pressure range investigated. The bulk modulus B-0 of beta-FeSi2 and its derivative B-0(') were determined to be 243.5 GPa and 3.2 GPa, respectively. A high-pressure phase, tentatively assigned to be tetragonal, appeared at about 20 GPa. For alpha-FeSi2, a higher temperature phase of beta-FeSi2, the bulk modulus B-0 and its derivative B-0(') were determined to be 183 GPa and 6.2 GPa, respectively. The experimental values of B-0 are compared with the values estimated by various first-principles calculations, where the characteristic tendency is shown. (C) 2004 American Institute of Physics., AMER INST PHYSICS
J. Appl. Phys., 2004年11月13日, ［査読有り］

Anisotropy of refractive indes of β-FeSi2
H. Udono; I. Kikuma; H. Tajima; K. Takarabe, Refractive index of beta-FeSi2 has been investigated by polarized optical reflection measurement on a bulk beta-FeSi2 single crystal and Kramers-Kronig analysis. Anisotropy of refractive index was clearly observed for the light polarization of E//a, E//b and E//c., IEEE
Proc. 1st Inter. Conf. on Group IV Photonics, 2004年09月29日, ［査読有り］

Indirect optical absorption of single crystalline β-FeSi2　　　　　　　　　　　　　　　
Haruhiko Udono; Isao Kikuma; Tsuyoshi Okuno; Yasuaki Masumoto; Hiroyuki Tajima
Appl. Phys. Lett., 2004年09月13日, ［査読有り］

Indirect optical absorption of single crystalline beta-FeSi2
H. Udono; I. Kikuma; T. Okuno; Y. Masumoto; H. Tajima
Applied Physics Letters, 2004年09月, ［査読有り］

Optical properties of β-FeSi2 single crystals grown from solutions
H. Udono; I. Kikuma; T. Okuno; Y. Masumoto; H. Tajima; S. Komuro
Thin Solid Films, 2004年08月29日, ［査読有り］

Electrical properties of p-type β-FeSi2 single crystals grown from Ga and Zn solvents
H. Udono; I. Kikuma
Thin Solid Films, 2004年08月29日, ［査読有り］

Thermal expansion of β-FeSi2 at low temperatures
Y. Terai; H. Ishibashi; Y. Maeda; H. Udono
Thin Solid Films, 2004年08月29日, ［査読有り］

Structural and electrical properties of β-FeSi2 single crystals grown using Sb solvent
H. Kannou; Y. Saito; M. Kuramoto; T. Takeyama; T. Nakamura; T. Matsuyama; H. Udono; Y. Maeda; M. Tanaka; Z. Q. Liu; H. Tatsuoka; H. Kuwabara, beta-FeSi2 bulk single crystals were grown using a temperature gradient solution growth (TGSG) process in Sb solvent. The microstructura(l) and electrical properties of the beta-FeSi2 were then characterized. Rectangular-shaped single crystals were basically obtained with facetted crystallographic planes having the predominant growth direction of beta-FeSi2 [011]. No evidence for the formation of 90degrees order domains around the a-axis, domain boundaries and long period structures was observed by transmission electron microscopy (TEM). It was also found that the crystal shows n-type behavior, and that the donor ionization energy deduced from the temperature dependence of the electron concentration is approximately 0.12-0.15 eV. The nature of defects will be discussed along with the photoconductivity and the electron spin resonant (ESR) measurements. (C) 2004 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2004年08月29日, ［査読有り］

Raman spectra for β-FeSi2 bulk crystals
Y. Maeda; H. Udono; Y. Terai
Thin Solid Films, 2004年08月29日, ［査読有り］

Reflection and absorption spectra of β-FeSi2 under pressure
Y. Mori; Y. Sumida; K. Takarabe; T. Suemasu; F. Hasegawa; H. Udono; I. Kikuma, High-pressure optical reflection and absorption study of beta-FeSi2 were carried out up to 5.0 and 4.8 GPa, respectively at room temperature. By the absorption experiment, the pressure coefficient of the direct band gap was determined to be 15.9 meV/GPa. On the other hand, the pressure dependence of dielectric functions were obtained by using Kramers-Kronig relations for the reflection spectra and the pressure coefficients of three different higher energy gap were tentatively evaluated to be 8.73, 8.63 and 16.7 meV/GPa, respectively. These pressure coefficients are quite smaller than those of II-VI, III-V and group IV common semiconductors. We propose that the small pressure coefficient is caused by not only the larger bulk modulus compared with common semiconductors but also the shift of the valence band maximum of beta-FeSi2 to higher energy with increasing pressure. (C) 2004 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
Thin Solid Films, 2004年08月29日, ［査読有り］

Thin Solid Films: Preface
Maeda, Y.Y.; Homewood, K.P.; Suemasu, T.; Sadoh, T.; Udono, H.; Kenji, Y.
Thin Solid Films, 2004年

Control of Ga Doping Level in β-FeSi2 using Sn-Ga Solvent
H. Udono; K. Matsumura; I. J. Ohsugi; I. Kikuma
Mat. Sci. Semicon. Proc., 2003年11月, ［査読有り］

Etch Pits Observation and Etching Properties of β-FeSi2
H. Udono; I. Kikuma
Mat. Sci. Semicon. Proc., 2003年11月, ［査読有り］

Solution Growth and Optical Characterization of β-FeSi2 Bulk Crystals
H. Udono; I. Kikuma, We have succeeded in growing large-sized β-FeSi₂ crystal (10 mm in diameter and 0.3-0.5 mm in thickness) by a temperature gradient solution growth method using a carbon plate. The grown crystals had large-sized grain boundaries with an area of about (1-2)× (1-4) mm². Optical absorption measurements were performed at room temperature on single crystalline specimens prepared from the grown crystals. The absorption spectra suggest that β-FeSi₂ has an indirect band-gap structure with a gap energy of approximately 0.75 eV., 公益社団法人 応用物理学会
Jpn. J. Appl. Phys., 2002年05月, ［査読有り］

Crystal Growth of β-FeSi2 by Temperature Gradient Solution Growth Method using Zn Solvent
H. Udono; S. Takaku; I. Kikuma, Single crystalline beta-FeSi2 with a low carrier density has been grown by a temperature gradient solution growth method using Zn solvent. The crystals were polyhedral with clear growth facets. Hall measurements revealed that the crystals showed p-type conductivity. The hole concentration and Hall mobility at room temperature were about 4 x 10(17) cm(-3) and about 19 cm(2)/Vs, respectively. (C) 2002 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
J. Crystal Growth, 2002年04月, ［査読有り］

Growth and Characterization of Br-doped ZnSe Single Crystals Grown by Vertical Sublimation Method
H. Kato; H. Udono and I. Kikuma, Bromine doping of ZnSe single crystals grown by using a vertical sublimation method was studied. ZnBr2 was used as a dopant at concentrations of 0.003 to 0.1 mg/cm(3) in the ampoules. When the Br-doping was 0.01 mg/cm(3) or less, the average growth rate of the crystals was about 34 mg/h cm(2); the same as that without doping. When the Br-doping exceeded 0.01 mg/cm(3), the average growth rate decreased with increasing dopant concentration. The undoped ZnSe crystals were yellow, whereas the Br-doped ZnSe crystals were orange. The high quality of the grown crystals was confirmed by X-ray diffraction (XRD), which showed that the full width at half maximum (FWHM) of the rocking curve ranged from 6.7 to 8.9 arcs. Bromine concentration of the grown crystals ranged from 4 x 10(17) to 1.5 x 10(19) cm(-3) (measured by secondary ion mass spectrometry, SIMS), depending on the dopant concentration. All of the as-grown crystals showed high resistivity. After growth, all of the grown crystals were annealed in a Zn atmosphere at 1100 degreesC for 100 h to activate the bromine as an n-type donor. When the dopant concentration was increased, the carrier concentration of Br-doped ZnSe increased from 1.4 to 4.1 x 10(17) cm(-3) and the mobility decreased from 366 to 146 cm(2)/Vs (determined by Hall effect measurements). Our results show that high quality, low resistivity ZnSe single crystals can be grown by this vertical sublimation method. (C) 2001 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
J. Crystal Growth, 2001年07月, ［査読有り］

Observation of Etch Pits of β-FeSi2 Single Crystals
H. Udono; I. Kikuma, We have observed etch pits of p-type beta -FeSi2 single crystals grown by the temperature gradient solution growth method. Characteristic etch pits which depend on the surface orientation of the crystals were observed on the surface etched by diluted hydrofluoric acid and HF : HNO3 : H2O = 1 : 2 : 2-8 solutions. These etchants are suitable for the observation of etch pits and surface orientation of beta -FeSi2 single crystals., INST PURE APPLIED PHYSICS
Jpn. J. Appl. Phys., 2001年06月, ［査読有り］

β-FeSi2 Single Crystals Grown from Solution
H. Udono; I. Kikuma, We have grown high-quality beta -FeSi2 bulk single crystals by a temperature gradient solution growth method using Ga solvent. Polyhedral shaped bulk crystals with clear facet planes were obtained below the growth temperature of 900 degreesC. Laue observation confirmed that crystals are high-quality single crystals without twins. Full-width at half maxim of the X-ray rocking curve at beta -FeSi2 (800) reflection was 53 arcsec. The conduction was p-type and the resistivity was 0.03-0.04 Omega cm at room temperature., INST PURE APPLIED PHYSICS
Jpn. J. Appl. Phys., 2001年03月, ［査読有り］

Effect of solution thickness on ZnSe crystals grown fron Se/Te mixed solutions
H. Kato; H. Udono and I. Kikuma, ZnSe single crystals were grown on a ZnSe(1 1 1)A seed from Se/Te mixed solutions. Effect of the thickness of the solution between a seed crystal and a source crystal on ZnSe crystals grown by the temperature gradient solution (TGS) method was studied for various distances. For the range of the solution thickness studied here (0.1-80 mm), the growth rate strongly depended on this thickness. Single crystals were obtained when the solution thickness was either 2 mm or less, or 30 mm or more, whereas polycrystals were obtained when the thickness was between 5 and 20 mm. The grown single crystals were characterized by using X-ray diffraction (XRD), photoluminescence (PL) at 4.2 K, and inductively coupled plasma mass spectrometry (ICP-MS). When a Se/Te solution was used, a solution thickness of either 0.5 or 50 mm produced grown-single crystals with the same crystallographic quality; the value of the full width at half maximum (FWHM) of X-ray rocking curve (XRC) was 5.2-6.0 arcsec, the lattice parameter was 5.6705 Angstrom measured by the Bond method, the Te concentration in the grown crystals was 0.12% (measured by using ICP-MS), and the PL spectrum was dominated by the emission from the Te isoelectronic trap of 2.69 eV. Our results show that the crystal growth changed from convection-limited to diffusion-limited depending on the solution thickness and that high-quality ZnSe single crystals can be grown by this TGS method. (C) 2000% Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
J. Crystal Growth, 2000年11月, ［査読有り］

β-FeSi2 Bulk Crystals Grown by the Temperature Gradient Solution Growth Method using Ga Solvent　　　　　　　　　　　　　　　
H. Udono; I. Kikuma
Proc. Japan - UK joint workshop on KANKYO semiconductors, Tsukuba, 2000年08月, ［招待有り］

Growth of β-FeSi2 on Si subsrtrate from liquid phase　　　　　　　　　　　　　　　
H. Udono; M. Tada; I. Kikuma
Proc. Japan - UK joint workshop on KANKYO semiconductors, Tsukuba, 2000年08月

The effect of (Al, I) impurities and heat treatment on lattice paramaeter of single-crystal
H. Udono; I. Kikuma and Y. Okada, We have measured the precise lattice parameter of undoped and impurity-doped ZnSe single crystals by the Fewster method. The lattice parameter of undoped ZnSe single crystals was 0.566919 +/- 0.000002 nm and it remained unchanged after the Zn-treatment at 1000 degrees C. On the other hand, dilation of lattice parameter observed in I-doped ZnSe depended on Zn-treatment temperature, Increase of lattice parameter also occurred in Al-doped ZnSe. These results suggest that I and Al impurities in ZnSe crystal play an important role with point defects formation during and after the Zn heat treatment. (C) 2000 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
J. Crystal Growth, 2000年06月, ［査読有り］

Solution Growth of Single-Phase β-FeSi2 Bulk Crystals
H. Udono; I. Kikuma, We have succeeded in growing single-phase beta-FeSi2 crystals by a temperature gradient solution growth method. FeSi2 solute and Ga solvent were placed in a quartz ampule, which was evacuated under a high vacuum (< 2 x 10(-6) Torr) and sealed with a quartz rod. The ampule was heated for 24-144 h in a gradient temperature profile. The grown crystals had multiple facet planes and the color was metallic silver white. X-ray diffraction showed that the grown crystals were single-phase beta-FeSi2. The conduction of the beta-FeSi2 grown crystals was p-type and the resistivity was between 0.05 and 0.2 Omega.cm., JAPAN J APPLIED PHYSICS
Jpn. J. Appl. Phys., 2000年03月

Dependence of lattice parameter of melt-grown ZnSe on Zn partial pressure during in-situ annealing
H. Udono; I. Kikuma and Y. Okada, Lattice parameters of annealed ZnSe crystals have been measured by the Bond method. The annealing was carried out at 1000 degrees C under a definite Zn partial pressure maintained by heating a Zn reservoir after growth from the melt under Zn partial pressure. The lattice parameter, a, depends on the Zn reservoir temperature during annealing, T-Zn(A); a = 0.566898 +/- 0.000005 nm at T-Zn(A) of 450-600 degrees C, a = 0.566910 +/- 0.000005 nm at T-Zn(A) of 750 degrees C and a = 0.566913 +/- 0.000003 nm at T-Zn(A) of 900 degrees C. The dependence of lattice parameter on Zn partial pressure is discussed. (C) 1999 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
J. Crystal Growth, 1999年02月

Lattice paramaeter of ZnSe crystals grown from melt under Zn partial pressure
H. Udono; I. Kikuma and Y. Okada, Dependence of the lattice parameter of melt-grown ZnSe on Zn partial pressure have been measured by the Bond method. The lattice parameters changed between 0.566902 and 0.566908 nm depending on the partial pressure of Zn during growth. The minimum lattice parameter was observed at the Zn reservoir temperature of 1000 degrees C, where the melt composition was near stoichiometry. (C) 1998 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
J. Crystal Growth, 1998年09月, ［査読有り］

Rapid diffusion of V elements during the conversion of GaAs to GaAsP on a GaP substrate
M. Kimura; Z. Qin; S. Dost; H. Udono; A. Tanaka and T. Sukegawa, A computational model for mass transport occurring during the conversion of GaAs to GaAsP on a GaP substrate is presented, The mass transport equations in the liquid and solid phases, and the phase diagram together with appropriate interface and boundary conditions were solved numerically by the finite element method. Numerical solutions agree with experimental results and explain well the conversion phenomenon, The conversion process is initiated by the non-equilibrium condition between the Ga-As-P solution and the GaAs layer and promoted by the rapid diffusion of V elements into the GaAs (GaAsP conversion) layer. Further analysis shows that the period required for the conversion increases parabolically with increasing thickness of the GaAs layer., ELSEVIER SCIENCE BV
Appl. Surf. Sci., 1997年04月, ［査読有り］

Conversion mechanism of GaAs to GaAsP on GaP substrate
M. Kimura; Z. Qin; H. Udono; S. Dost; A. Tanaka and T. Sukegawa, A computational model for mass transport occurring during the conversion of GaAs to GaAsP on a GaP substrate is presented. The mass transport equations in the liquid and solid phases, and the phase diagram together with appropriate interface and boundary conditions were solved numerically by the finite element method (FEM). Numerical solutions agree with experimental results and explain well the conversion phenomenon. (C) 1997 Elsevier Science S.A., ELSEVIER SCIENCE SA LAUSANNE
Materials Sci. & Eng. B, 1997年02月, ［査読有り］

A numerical analysis for the conversion phenomenon of GaAs to GaAsP on GaP substrate in an LPE system
M. Kimura; S. Dost; H. Udono; A. Tanaka; T. Sukegawa and Z. Qin, A computational model for the mass transport occurring during the conversion of GaAs to GaAsP on a GaP substrate is presented. The mass transport equations in the liquid and solid phases, and the equations describing phase diagram constitute the governing equations. These equations together with appropriate interface and boundary conditions were solved numerically by the finite element method. Numerical solutions agree with experimental results and explain well the conversion phenomenon. The conversion process is initiated by the non-equilibrium condition between the Ga-As-P solution and the GaAs layer and promoted by the rapid diffusion of V elements into the GaAs (GaAsP conversion) layer., ELSEVIER SCIENCE BV
J. Crystal Growth, 1996年12月, ［査読有り］

Suppression of twins in GaAs layers grown on a GaP(111)B substrate by liquid phase epitaxy
H. Udono; A. Motogaito; M. Kimura; A. Tanaka and T. Sukegawa, Heteroepitaxial growth of GaAs on GaP(111)B was demonstrated by liquid phase epitaxy. In order to suppress the generation of rotational twins, initial saturation conditions of Ga-As solution contacting with a GaP substrate were investigated at 800 degrees C. Supersaturated and undersaturated solutions caused a number of twins in the grown GaAs layer, while saturated solution led only a few percents in volume. It was concluded that near equilibrium contact is effective to reduce the twins., ELSEVIER SCIENCE BV
J. Crystal Growth, 1996年11月, ［査読有り］

Conversion of GaAs Layer Grown on GaP Substrate to GaAsP in LPE System
H. Udono; H. Katsuno; A. Tanaka and T. Sukegawa, A new fabrication technique of GaAsP layers with a desired composition on a GaP substrate was developed. A GaAs layer grown on a GaP substrate by step cooling was brought into contact with Ga-As-P saturated solution and kept at 795-degrees-C. This annealing process resulted the compositional conversion of the GaAs layer to GaAsP. The composition of the conversion layer could be controlled by adjusting the composition of the Ga-As-P solution. Fairly good GaAsP layers were grown on the conversion layer by a consecutive slow cooling after the conversion process., JAPAN J APPLIED PHYSICS
Jpn. J. Appl. Phys., 1993年12月, ［査読有り］

Conversion from GaAs to GaAsP by annealing a GaAs layer on GaP in Ga-As-P solution
T. Sukegawa; H. Udono; M. Kimura; H. Katsuno; A. Tanaka, A new liquid phase epitaxial (LPE) technique of preparing alloy layers of a desired composition lattice-mismatched with a substrate has been developed. A GaAs layer was grown on a GaP substrate through step cooling from 800-degrees-C to 795-degrees-C, followed by contact with Ga-As-P solution at a constant temperature of 795-degrees-C. This treatment led to a transformation in the composition of the grown GaAs to GaAsP. Thus a GaAsP layer with the composition of 0.65 GaAs mole fraction, which was not grown directly on GaP, could be prepared on GaP substrates., JAPAN SOC APPLIED PHYSICS
Jpn. J. Appl. Phys., 1993年08月, ［査読有り］

〔主要な業績〕Mg2Si基板開発と赤外線センサへの展開
鵜殿 治彦
レーザー研究, 2022年10月15日, ［招待有り］

〔主要な業績〕マグネシウムシリサイドを用いた環境調和型赤外フォトダイオード
鵜殿 治彦
応用物理, 2019年12月10日, ［招待有り］

〔主要な業績〕赤外センサ用Mg₂Si結晶の融液成長
鵜殿 治彦
日本結晶成長学会誌, 2018年10月, ［招待有り］

Si中Cu，Niの熱的振る舞い：フォトルミネッセンス/DLTS測定
中村 稔; 村上 進; 鵜殿 治彦
表面科学, 2016年03月

K₈Ga₈Si₃₈クラスレート単結晶の光物性評価
飯岡優; 鵜殿治彦; 今井基晴; 田島裕之
電気学会東京支部茨城支所研究発表会講演予稿集, 2013年

K₈Ga₈Si₃₈クラスレートの光学特性評価
飯岡優; 鵜殿治彦; 今井基晴; 田島裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2013年

〔主要な業績〕見直され始めたシリサイド系熱電材料
鵜殿治彦
日本熱電学会誌, 2012年03月, ［招待有り］

25aTJ-11 半導体Siクラスレートの探索(25aTJ 籠状物質(クラスレート化合物),領域7(分子性固体・有機導体))
今井 基晴; 佐藤 晃; 今井 庸ニ; 鵜殿 治彦; 田島 裕之
日本物理学会講演概要集, 2011年

資源・環境リスクに対応するシリサイド半導体の育成と物性評価
鵜殿治彦
第28回無機材料に関する最近の研究成果講演予稿集, 2011年01月, ［招待有り］

Fluorescence EXAFS study of residual Ga in β-FeSi2 grown from Ga solvent
H Yamada; M Tabuchi; Y Takeda; H Udono
Journal of Physics: Conference Series, 2009年06月, ［査読有り］

〔主要な業績〕半導体シリサイドの結晶成長と基礎物性
鵜殿治彦
応用物理, 2007年07月10日, ［招待有り］

〔主要な業績〕鉄シリサイドバルク成長と特性
鵜殿治彦
機能材料, 2005年09月05日, ［招待有り］

シリサイド半導体の基礎物性
前田佳均,鵜殿治彦
日本学術振興会未踏・ナノデバイステクノロジー第151委員会，第65回研究会資料, 2003年05月

β-FeSi2バルク結晶の光吸収
鵜殿治彦
第3回シリサイド系半導体研究会講演予稿, 2003年03月

23aTL-4 環境半導体 β-FeSi_2 の電子構造の圧力効果
財部 健一; 住田 行常; 井貝 智行; 寺西 良太; 森 嘉久; 鵜殿 治彦; 末益 崇; 長谷川 文夫
日本物理学会講演概要集, 2003年

β-FeSi2の吸収特性
鵜殿治彦
「2002年シリサイド系半導体・夏の学校」研究会資料, JAERI-Conf 2002-014, 2002年08月

6aSB-8 β-FeSi_2の高圧物性(II)(層状・低次元物質・化合物半導体,領域4)
井貝 智行; 森 嘉久; 財部 健一; 住田 行常; 桜又 英憲; 鵜殿 治彦; 菊間 勲
日本物理学会講演概要集, 2002年

24pSA-5 β-FeSi_2の高圧物性(24pSA 化合物半導体,層状・低次元物質,領域4(半導体,メゾスコピック系・局在分野))
財部 健一; 森 嘉久; 井貝 智行; 糸数 智啓; 鵜殿 治彦
日本物理学会講演概要集, 2002年

半導体鉄シリサイドバルク結晶の溶液成長
鵜殿治彦
材料科学, 2000年09月, ［招待有り］

熱電変換材料 実用・活用を目指した設計と開発　　　　　　　　　　　　　　　
共著
情報機構, 2014年12月19日

シリサイド系半導体の科学と技術-資源･環境時代の新しい半導体と関連物質-　　　　　　　　　　　　　　　
前田佳均編著, 共著
裳華房, 2014年09月25日

サーマルマネージメント-余熱・排熱の制御と有効利用- 第4章第1節1.1 シリサイド系熱電材料の開発　　　　　　　　　　　　　　　
鵜殿治彦, 単著
株）エヌ・ティー・エス, 2013年04月17日
9784864690607

Thermoelectrics and its Energy Harvesting Chap.18 "Preparation and thermoelectric properties of Iron Disilicide "　　　　　　　　　　　　　　　
Y. Isoda; H. Udono, 共著
CRC Press, 2012年
9781439874707

エピタキシャルMg3Bi2薄膜の大気安定性および熱電性能評価　　　　　　　　　　　　　　　
栗山 武琉; 鮎川 瞭仁; 根城 虹希; 鵜殿 治彦; 坂根 駿也
第72回応用物理学会春期学術講演会, 2025年03月17日

エピタキシャルMg3Sb2/Mg3Bi2薄膜の電気特性と構造評価　　　　　　　　　　　　　　　
根城 虹希; 鮎川 瞭仁; 切通 望; 栗山 武琉; 鵜殿 治彦; 坂根 駿也
第72回応用物理学会春期学術講演会, 2025年03月16日

スパッタリング堆積法によるSi基板上へのInSb薄膜の成長と評価　　　　　　　　　　　　　　　
小金澤 藍登; 久保田 啓聖; 鮎川 瞭仁; 坂根 駿也; 鵜殿 治彦
第72回応用物理学会春期学術講演会, 2025年03月16日

平底pBN坩堝からブリッジマン成長したMg2Si結晶の結晶成長方位　　　　　　　　　　　　　　　
鉄幸多朗; 島野航輔; 木村侑生; 藤久善司; 坂根駿也; 鵜殿治彦
第72回応用物理学会春期学術講演会, 2025年03月16日

Ag拡散源の膜厚によるMg2Si-PDの受光感度への影響　　　　　　　　　　　　　　　
飯野有紀; 武井日出人; 尾嶋海人; 坂根駿也; 鵜殿治彦
第72回応用物理学会春期学術講演会, 2025年03月16日

Mg3Sb2薄膜への不純物ドーピングに向けたイオン注入法の検討　　　　　　　　　　　　　　　
坂根 駿也; 鮎川 瞭仁; 切通 望; 栗山 武琉; 根城 虹希; 鵜殿 治彦
第72回応用物理学会春期学術講演会, 2025年03月15日

c-Al2O3基板上Mg3Bi2薄膜のエピタキシャル成長及び熱電特性評価　　　　　　　　　　　　　　　
鮎川 瞭仁; 栗山 武流; 根城 虹希; 鵜殿 治彦; 坂根 駿也
第72回応用物理学会春期学術講演会, 2025年03月15日

短波赤外イメージセンサに向けたMg2Si-PDリニアアレイの試作(II)　　　　　　　　　　　　　　　
古田良輔; 尾嶋海人; 武井日出人; 勝俣響; 坂根駿也; 鵜殿治彦
第72回応用物理学会春期学術講演会, 2025年03月14日

Si(001)基板上に作製したエピタキシャルMg3Sb2薄膜の赤外受光特性　　　　　　　　　　　　　　　
切通 望; 鮎川 瞭仁; 根城 虹希; 栗山 武琉; 山本 若葉; 安原 聡; 佐藤 康平; 鵜殿 治彦; 坂根 駿也
第72回応用物理学会春期学術講演会, 2025年03月14日

Mg2Siのラマンスペクトルと第一原理計算によるフォノンダイナミクス解析　　　　　　　　　　　　　　　
島野航輔; 太田岳宏; 高倉健一郎; 坂根駿也; 鵜殿治彦
第72回応用物理学会春期学術講演会, 2025年03月14日

Fabrication of Mg2Si linear photodiode arrays for SWIR imaging　　　　　　　　　　　　　　　
Haruhiko UDONO; Kaito Ojima; Naoki Imaizumi; Hideto Takei; Shunya Sakane
SPIE Photonics West 2025, 2025年01月28日

エピタキシャル Mg3SbBi 薄膜における電気特性の温度依存性　　　　　　　　　　　　　　　
根城 虹希; 栗山 武琉; 鮎川 瞭仁; 切通 望; 鵜殿 治彦; 坂根 駿也
令和6年度 電気学会東京支部茨城支所研究発表会, 2024年11月30日

シリコン基板上の InSb のスパッタ成膜　　　　　　　　　　　　　　　
小金澤藍登; 久保田啓聖; 鮎川瞭仁; 坂根駿也; 鵜殿治彦
令和6年度 電気学会東京支部茨城支所研究発表会, 2024年11月30日

c-Al2O3 基板上エピタキシャル Mg3Bi2 薄膜の大気安定性の向上　　　　　　　　　　　　　　　
栗山武琉; 鮎川瞭仁; 鵜殿治彦; 坂根駿也
令和6年度 電気学会東京支部茨城支所研究発表会, 2024年11月30日

平坦坩堝からブリッジマン成長した Mg2Si結晶の成長方位と結晶性評価　　　　　　　　　　　　　　　
鉄幸多朗; 島野航輔; 藤久善司; 木村侑生; 鵜殿治彦; 坂根駿也
令和6年度 電気学会東京支部茨城支所研究発表会, 2024年11月30日

低温・バイアス下におけるマグネシウムシリサイドフォトダイオードの分光感度　　　　　　　　　　　　　　　
古田良輔; 勝俣響; 坂根駿也; 鵜殿治彦
令和6年度 電気学会東京支部茨城支所研究発表会, 2024年11月30日

微細加工によるマグネシウムシリサイドフォトダイオードのAg 拡散条件と分光感度　　　　　　　　　　　　　　　
勝俣響; 古田良輔; 尾嶋海人; 武井日出人; 坂根駿也; 鵜殿治彦
令和6年度 電気学会東京支部茨城支所研究発表会, 2024年11月30日

Epitaxial Growth of High-quality Mg3Sb2-based Thin Films and Their Thermoelectric Properties　　　　　　　　　　　　　　　
Akito Ayukawa; Nozomu Kiridoshi; Takeru Kuriyama; Wakaba Yamamoto; Akira Yasuhara; Haruhiko Udono; Shunya Sakane
The 21st International Conference on Flow Dynamics, 2024年11月18日

Sc 添加したMg3(Sb,Bi)2結晶合成と熱電特性評価　　　　　　　　　　　　　　　
小金澤直; 鮎川瞭仁; 坂根駿也; 鵜殿治彦
第 21 回日本熱電学会学術講演会, 2024年09月25日

c-Al2O3 基板上へのエピタキシャル Mg3Bi2 薄膜の作製条件探索及び熱電特性評価　　　　　　　　　　　　　　　
鮎川 瞭仁; 栗山 武流; 鵜殿 治彦; 坂根 駿也
第 21 回日本熱電学会学術講演会, 2024年09月24日

同時蒸着によるSi(001)基板上エピタキシャルMg3Sb2薄膜の作製　　　　　　　　　　　　　　　
切通 望; 鮎川 瞭仁; 山本 若葉; 安原 聡; 佐藤 康平; 鵜殿 治彦; 坂根 駿也
第85回応用物理学会秋季学術講演会, 2024年09月18日

c-Al2O3基板上エピタキシャルMg3Bi2薄膜の成長条件の探索　　　　　　　　　　　　　　　
鮎川 瞭仁; 栗山 武流; 鵜殿 治彦; 坂根 駿也
第85回応用物理学会秋季学術講演会, 2024年09月18日

歪み緩和したエピタキシャルMg3Sb2薄膜の熱電特性　　　　　　　　　　　　　　　
坂根 駿也; 鮎川 瞭仁; 切通 望; 山本 若葉; 安原 聡; 山下 雄一郎; 鵜殿 治彦
第85回応用物理学会秋季学術講演会, 2024年09月17日, ［招待有り］

不純物ドープしたMg2Si単結晶のラマン分光測定　　　　　　　　　　　　　　　
島野航輔; 鵜殿治彦; 坂根駿也
第85回応用物理学会秋季学術講演会, 2024年09月17日

Mg2Si単結晶成長に及ぼす坩堝形状の影響　　　　　　　　　　　　　　　
朝倉康太; 劉鑫; 鵜殿治彦; 宇佐美徳隆
第85回応用物理学会秋季学術講演会, 2024年09月17日

Mg2Si-PDアレイの窒化シリコン絶縁膜の暗電流への影響　　　　　　　　　　　　　　　
武井日出人; 尾嶋海人; 坂根駿也; 鵜殿治彦
第85回応用物理学会秋季学術講演会, 2024年09月17日

短波赤外イメージセンサに向けたMg2Si-PDリニアアレイの試作　　　　　　　　　　　　　　　
今泉尚己; 尾嶋海人; 武井日出人; 坂根駿也; 鵜殿治彦
第85回応用物理学会秋季学術講演会, 2024年09月17日

n型基板上に熱拡散で作製したMg2Si-TPVセルの出力特性への基板キャリア濃度の影響　　　　　　　　　　　　　　　
清水匠; 島野航輔; 坂根駿也; 鵜殿治彦
第85回応用物理学会秋季学術講演会, 2024年09月16日

φ50mmサイズMg2Si結晶の単結晶化機構の調査　　　　　　　　　　　　　　　
藤久善司; 木村侑生; 島野航輔; 坂根駿也; 劉鑫; 宇佐美徳隆; 鵜殿治彦
第85回応用物理学会秋季学術講演会, 2024年09月16日

Epitaxial Growth of Zintl Phase Mg3Sb2 Thin Films on Si (001) Substrate by Simultaneous Deposition　　　　　　　　　　　　　　　
Nozomu Kiridoshi; Akito Ayukawa; Haruhiko Udono; Shunya Sakane
ICMBE 2024, 2024年09月12日

High-quality Mg3Sb2 Epitaxial Thin Films with Few Defects Grown Directly on c-plane Al2O3 Substrates　　　　　　　　　　　　　　　
Akito Ayukawa; Nozomu Kiridoshi; Wakaba Yamamoto; Haruhiko Udono; Shunya Sakane
ICMBE 2024, 2024年09月12日

Evaluation of Mg2Si-TPV cells fabricated on n-Mg2Si substrate by thermal diffusion of Ag acceptor　　　　　　　　　　　　　　　
Takumi Shimizu; Daisuke Miyago; Syunya Sakane; Haruhiko Udono
International Conference on Solid State Devices and Materials (SSDM2024), 2024年09月03日

熱電材料の基礎とシリサイド系半導体の応用例　　　　　　　　　　　　　　　
鵜殿治彦
2024年度シリサイド夏の学校, 2024年07月21日, ［招待有り］

熱処理した c 面 Al2O3 基板上への高品質 Mg3Sb2 薄膜のエピタキシャル成長とその熱電特性　　　　　　　　　　　　　　　
鮎川瞭仁; 切通望; 山本若葉; 坂根駿也; 鵜殿治彦
2024年度シリサイド夏の学校, 2024年07月20日

熱拡散法により作製された Mg2Si-TPV セルの性能評価　　　　　　　　　　　　　　　
清水匠; 宮後大介; 坂根駿也; 鵜殿治彦
2024年度シリサイド夏の学校, 2024年07月20日

ラマン分光による Mg2Si 基板上 Ag 薄膜の熱処理に反応の評価　　　　　　　　　　　　　　　
武井日出人; 尾嶋海人; 久保田啓聖; 坂根駿也; 鵜殿治彦
2024年度シリサイド夏の学校, 2024年07月20日

p 型 Mg2Si 単結晶の不純物と電気的特性　　　　　　　　　　　　　　　
藤久善司; 木村侑生; 島野航輔; 坂根駿也; 鵜殿治彦
2024年度シリサイド夏の学校, 2024年07月20日

熱拡散でMg2Si 基板上に作製したpn接合ダイオードの暗電流への基板中のキャリア濃度の影響　　　　　　　　　　　　　　　
島野航輔; 植松達哉; 坂根駿也; 鵜殿治彦
2024年度シリサイド夏の学校, 2024年07月20日

Thermoelectric performance of epitaxially grown Mg3Sb2 thin films on sapphire substrates　　　　　　　　　　　　　　　
Shunya Sakane; Akito Ayukawa; Nozomu Kiridoshi; Yuichiro Yamashita; Haruhiko Udono
The 40th International Conference on Thermoelectrics (ICT2024), 2024年07月04日

基板表面の原子配列制御による高品質エピタキシャル Mg3Sb2 薄膜の作製　　　　　　　　　　　　　　　
鮎川瞭仁; 切通望; 山本若葉; 坂根駿也; 鵜殿治彦
ナノ学会第 22 回大会, 2024年05月23日

Development of single crystalline Mg2Si substrate for Mg2Si SWIR sensor　　　　　　　　　　　　　　　
Haruhiko UDONO
7 th International Conference on Nanoscience and Nanotechnology (ICONN-2023), 2023年03月29日, ［招待有り］
20230327, 20230329

4探針プローブ法によるMg2Si基板へのAl拡散深さの調査　　　　　　　　　　　　　　　
尾嶋海人; 中村陸斗; 鵜殿治彦
第70回応用物理学会春期学術講演会, 2023年03月16日
20230315, 20230318

2011年 - 現在, 日本熱電学会

2008年 - 現在, 米国材料科学会

2001年 - 現在, 応物 シリサイド系半導体及び関連物質研究会

1993年 - 現在, 応用物理学会

2006年, 米国物理学会

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