TOHOKU UNIVERSITY Researchers

Details of the Researcher

Home

日本語 English

Kozo Fujiwara

Section

Institute for Materials Research

Job title

Professor

Degree

博士（工学）（九州大学）
修士（工学）（九州大学）

researchmap

https://researchmap.jp/read0075745

J-GLOBAL ID

200901076003379650

Committee Memberships 3

日本学術振興会 R032 産業イノベーションのための結晶成長委員会　運営委員

2021/04 - Present
日本結晶成長学会　理事

2010/04 - Present
日本結晶成長学会　理事

2010/04 - Present

Professional Memberships 3

鉄鋼協会
日本結晶成長学会
日本金属学会

Research Interests 1

melt growth. In situ observation. silicon. solar cell. control of crystalographic orientation. grain boundary. semiconductor alloys. compound semiconductor

Research Areas 2

Nanotechnology/Materials / Metallic materials / diffusion in intermetallic compound
Natural sciences / Semiconductors, optical and atomic physics / crystal growth

Awards 6

文部科学大臣表彰科学技術賞（研究部門）

2020/04　文部科学省　太陽電池用シリコン多結晶インゴットの高品質化の研究
第34回本多記念研究奨励賞

2013/05/31　（公財）本多記念会　Siの融液成長メカニズムの解明および太陽電池用Si多結晶インゴットの成長技術開発
日本結晶成長学会論文賞

2011/11/03　日本結晶成長学会
原田研究奨励賞

2006/07/10　本多記念会
日本結晶成長学会奨励賞

2005/08/17　日本結晶成長学会
Photo Contest Award

2003/07/23　American Conference on Crystal Growth and Epitaxy

Show all ︎Show 5

Papers 221

Polymorphic transitions during nonclassical nucleation and growth in the colloidal heteroepitaxy

Jun Nozawa, Masahide Sato, Satoshi Uda, Kozo Fujiwara

Communications Physics　8　(1)　2025/04/09
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s42005-025-02062-9 　

eISSN： 2399-3650
The effect of phonon-phonon interaction in Ta based Heusler alloys for accurate phonon transport properties Peer-reviewed

Shobana Priyanka D., Srinivasan Manickam, Fujiwara K.

Journal of the Taiwan Institute of Chemical Engineers　169　105956-1-105956-13　2025/04

DOI： 10.1016/j.jtice.2025.105956 　
Ultra-low lattice thermal conductivity in 18 VEC quaternary Heusler alloys—Efficient thermoelectric materials Peer-reviewed

Shobana Priyanka D, M. Srinivasan, Kozo Fujiwara

Journal of Applied Physics　137　(12)　2025/03/26
Publisher: AIP Publishing
DOI： 10.1063/5.0252652 　

ISSN： 0021-8979

eISSN： 1089-7550

More details Close

Quaternary Heusler alloys are known for their distinctive electrical and thermal properties, present fascinating opportunities for improving thermoelectric performance. By leveraging the unique characteristics of these alloys and employing advanced design strategies, we can drive significant improvements in waste heat treatment. In the present study, we have identified novel stable quaternary Heusler alloys guided by the 18-valence electron rule through ab initio calculations. The ground state properties of presented alloys have studied using the generalized gradient approximation, whereas the accurate bandgap values have been determined using mBJ and GGA + U. The Boltzmann transport equation is used to investigate the thermoelectric properties of the alloys. The alloys are stable at room temperature and even at a high temperature of 900 K. The investigated quaternary Heusler alloys, MgZrFeSn and MgHfFeSn have indirect bandgaps of 0.69 eV and 0.77 eV, respectively, under mBJ approximation. The presence of flatbands and degenerated valley bands near the edges of the conduction and valence bands significantly enhance both the Seebeck coefficient and electrical conductivity of the alloys. Strong interactions between acoustic and optical phonon modes result in low lattice thermal conductivity of 0.58 and 1.49 W/m K at 900 K. This leads to high figure of merit of 1.28 and 1.55 for MgZrFeSn and MgHfFeSn, respectively, indicating their potential for advanced thermoelectric materials.
Single Crystal Growth of Type-II Si Clathrate Containing Fully Occupied Na and Ba from a Na-Based Metal Complex Solution Peer-reviewed

Haruhiko Morito, Yutaka IIjima, Masaya Fujioka, Rodion V. Belosludov, Masami Terauchi, Hisanori Yamane, Kozo Fujiwara

Crystal Growth & Design　2025/03/11
Publisher: American Chemical Society (ACS)
DOI： 10.1021/acs.cgd.5c00013 　

ISSN： 1528-7483

eISSN： 1528-7505
Multi-layer kagome lattices assembled with isotropic spherical colloids via heteroepitaxial growth Peer-reviewed

Jun Nozawa, Masahide Sato, Satoshi Uda, Kozo Fujiwara

Colloid and Interface Science Communications　64　100815-100815　2025/01
Publisher: Elsevier BV
DOI： 10.1016/j.colcom.2024.100815 　

ISSN： 2215-0382
In situ observation and numerical analysis of temperature gradient effects on growth velocity during directional solidification of silicon Peer-reviewed

Peiyao Hao, Lu-Chung Chuang, Kensaku Maeda, Jun Nozawa, Haruhiko Morito, Kozo Fujiwara, Lili Zheng

Journal of Materials Science　59　(39)　18446-18460　2024/10/01
Publisher: Springer Science and Business Media LLC
DOI： 10.1007/s10853-024-10277-4 　

ISSN： 0022-2461

eISSN： 1573-4803

More details Close

Abstract The < 110 > directional solidification of silicon under varying overall temperature gradients was investigated using an in situ observation system. The growth velocity of an atomically rough interface was found to decrease with increasing temperature gradient. A theoretical model of the thermal field taking undercooling into account was developed to describe this phenomenon and was demonstrated to be valid. The results of this work indicate that the reported linear relationship between growth velocity (V) and undercooling (ΔT), given by V (mm s⁻¹) = 120ΔT (K), is most accurate in the case of a rough interface. In the case that the overall temperature gradient is small, the melting point isotherm moves rapidly such that it becomes more difficult for the interface to keep pace with the isotherm compared with a large temperature gradient. This effect leads to increased undercooling at the interface and consequently a rapid growth velocity. Thermal field calculations confirm that a rapid increase in the ratio of the temperature gradient in the crystal to that in the melt should increase the latent heat release, again providing a more rapid growth velocity.
Computational analysis on novel half Heusler alloys X PdSi ( X = Ti, Zr, H f ) for waste heat recycling process Peer-reviewed

D.S. Priyanka, M. Srinivasan, J.B. Sudharsan, K. Fujiwara

MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING　180　108524-1-108524-12　2024/09

DOI： 10.1016/j.mssp.2024.108524 　
Dislocation interaction with vicinally faceted groove at grain boundary in multi-crystalline silicon Peer-reviewed

Fan Yang, Lu-Chung Chuang, Kensaku Maeda, Jun Nozawa, Haruhiko Morito, Kozo Fujiwara, Thierry Duffar

Journal of Crystal Growth　639　127722-127722　2024/08
Publisher: Elsevier BV
DOI： 10.1016/j.jcrysgro.2024.127722 　

ISSN： 0022-0248
Misorientation increase of small-angle grain boundaries during directional solidification of silicon Peer-reviewed

Lu-Chung Chuang, Kensaku Maeda, Jun Nozawa, Haruhiko Morito, Kozo Fujiwara

Journal of Crystal Growth　127822-127822　2024/07
Publisher: Elsevier BV
DOI： 10.1016/j.jcrysgro.2024.127822 　

ISSN： 0022-0248
Vicinal (111) surfaces at Si solid-liquid interface during unidirectional solidification Peer-reviewed

Shashank Shekhar Mishra, Lu Chung Chuang, Jun Nozawa, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara, Thierry Duffar

Scripta Materialia　247　2024/07/01

DOI： 10.1016/j.scriptamat.2024.116116 　

ISSN： 1359-6462
In situ study of growth kinetics of {1 0 0} and {1 1 0} crystal/melt interfaces during unidirectional solidification of silicon Peer-reviewed

Shashank Shekhar Mishra, Lu Chung Chuang, Kensaku Maeda, Jun Nozawa, Haruhiko Morito, Thierry Duffar, Kozo Fujiwara

Journal of Crystal Growth　627　2023/12/08

DOI： 10.1016/j.jcrysgro.2023.127524 　

ISSN： 0022-0248
Ferrimagnetic half Heusler alloys for waste heat recovery application- First principle study using different exchange-correlation functionals Peer-reviewed

2023/10

DOI： 10.1016/j.jmmm.2023.171409 　
Visualizing crystal twin boundaries of bismuth by high-spatial-resolution ARPES Peer-reviewed

2023/06

DOI： 10.1103/PhysRevResearch.5.023152 　
Epitaxial growth of SiGe films by annealing Al–Ge alloyed pastes on Si substrate International-journal Peer-reviewed

Keisuke Fukuda, Satoru Miyamoto, Masahiro Nakahara, Shota Suzuki, Marwan Dhamrin, Kensaku Maeda, Kozo Fujiwara, Yukiharu Uraoka, Noritaka Usami

Scientific Reports　12　(1)　14770-14770　2022/09/12
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-022-19122-7 　

eISSN： 2045-2322

More details Close

Abstract A simple, low-cost, and non-vacuum epitaxial growth method to realize large-area semiconductors on crystalline silicon will become the game-changer for various applications. For example, we can expect the disruptive effect on the cost of large-scale III–V multi-junction solar cells if we could replace the high-cost germanium substrate with silicon–germanium (SiGe) on Si. For SiGe epitaxial growth, we attempted to develop a process using original Al–Ge pastes for screen printing and subsequent annealing. We compare two pastes including Al–Ge alloyed pastes with compositional uniformity in each particle and Al–Ge mixed pastes. We revealed that Al–Ge alloyed paste could form flatter SiGe film with much less residual pastes, supported by in-situ observations. The uniform and sufficient dissolution of the alloyed paste is responsible for these and led to higher average Ge-composition by annealing at 500 °C. The composition in SiGe was vertically graded up to ~ 90% at the topmost surface. These results show that printing and firing of Al–Ge alloyed paste on Si is the desirable, simple, and high-speed process for epitaxial growth of SiGe, which could be potentially used as the lattice-matched virtual substrate with III–V semiconductors.
Difference in growth rates at {1 1 0} and {1 1 1} crystal/melt interfaces of silicon Peer-reviewed

Shashank Shekhar Mishra, Lu-Chung Chuang, Kensaku Maeda, Jun Nozawa, Haruhiko Morito, Kozo Fujiwara

Journal of Crystal Growth　593　126784-126784　2022/09
Publisher: Elsevier BV
DOI： 10.1016/j.jcrysgro.2022.126784 　

ISSN： 0022-0248
Thermoelectric performance of multiphase <scp>GeSe‐CuSe</scp> composites prepared by hydrogen decrepitation method Peer-reviewed

D. Sidharth, A.S. Alagar Nedunchezhian, R. Rajkumar, K. Kalaiarasan, M. Arivanandhan, K. Fujiwara, G. Anbalagan, R. Jayavel

International Journal of Energy Research　46　(12)　17455-17464　2022/07/20
Publisher: Hindawi Limited
DOI： 10.1002/er.8413 　

ISSN： 0363-907X

eISSN： 1099-114X
Facet formation during the solidification of pure antimony Peer-reviewed

Keiji Shiga, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara

Journal of Crystal Growth　586　126633-126633　2022/05
Publisher: Elsevier BV
DOI： 10.1016/j.jcrysgro.2022.126633 　

ISSN： 0022-0248
In situ observation of solidification and subsequent evolution of Ni-Si eutectics Peer-reviewed

Lu Chung Chuang, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara

Scripta Materialia　211　2022/04

DOI： 10.1016/j.scriptamat.2022.114513 　

ISSN： 1359-6462
Dynamics at crystal/melt interface during solidification of multicrystalline silicon Peer-reviewed

Kozo Fujiwara, Lu-Chung Chuang, Kensaku Maeda

HIGH TEMPERATURE MATERIALS AND PROCESSES　41　(1)　31-47　2022/02

DOI： 10.1515/htmp-2022-0020 　

ISSN： 0334-6455

eISSN： 2191-0324
Heteroepitaxial Growth of Colloidal Crystals: Dependence of the Growth Mode on the Interparticle Interactions and Lattice Spacing International-journal Peer-reviewed

Jun Nozawa, Satoshi Uda, Hiromasa Niinomi, Junpei Okada, Kozo Fujiwara

Journal of Physical Chemistry Letters　13　(30)　6995-7000　2022

DOI： 10.1021/acs.jpclett.2c01707 　

eISSN： 1948-7185
Twin boundary formation at a grain-boundary groove during the directional solidification of InSb Peer-reviewed

Keiji Shiga, Atsuko Takahashi, Lu-Chung Chuang, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara

JOURNAL OF CRYSTAL GROWTH　577　2022/01

DOI： 10.1016/j.jcrysgro.2021.126403 　

ISSN： 0022-0248

eISSN： 1873-5002
Segregation mechanism of arsenic dopants at grain boundaries in silicon Peer-reviewed

Yutaka Ohno, Tatsuya Yokoi, Yasuo Shimizu, Jie Ren, Koji Inoue, Yasuyoshi Nagai, Kentaro Kutsukake, Kozo Fujiwara, Atsutomo Nakamura, Katsuyuki Matsunaga, Hideto Yoshida

Science and Technology of Advanced Materials: Methods　1　(1)　169-180　2021/08/20
Publisher: Informa UK Limited
DOI： 10.1080/27660400.2021.1969701 　

eISSN： 2766-0400
Dendritic Growth in Si1-xGex Melts Peer-reviewed

Genki Takakura, Mukannan Arivanandhan, Kensaku Maeda, Lu-Chung Chuang, Keiji Shiga, Haruhiko Morito, Kozo Fujiwara

CRYSTALS　11　(7)　2021/07

DOI： 10.3390/cryst11070761 　

eISSN： 2073-4352
Seeded growth of type-ii na<inf>24</inf>si<inf>136</inf> clathrate single crystals Peer-reviewed

Haruhiko Morito, Hisanori Yamane, Rie Y. Umetsu, Kozo Fujiwara

Crystals　11　(7)　2021/07

DOI： 10.3390/cryst11070808 　

eISSN： 2073-4352
In situ observation of multiple parallel (1 1 1) twin boundary formation from step-like grain boundary during Si solidification Peer-reviewed

Kuan-Kan Hu, Kensaku Maeda, Keiji Shiga, Haruhiko Morito, Kozo Fujiwara

Appl. Phys. Express　13　105501-105501　2020/09
Enhancing the thermoelectric power factor of nanostructured ZnCo2O4 by Bi substitution Peer-reviewed

A. S. Alagar Nedunchezhian, D. Sidharth, R. Rajkumar, N. Yalini Devi, K. Maeda, M. Arivanandhan, K. Fujiwara, G. Anbalaganb, R. Jayavel

RSC Advances　10　18769-18775　2020/05
In situ observation of the solidification interface and grain boundary development of two silicon seeds with simultaneous measurement of temperature profile and undercooling Peer-reviewed

Victor Lau, Kensaku Maeda, Kozo Fujiwara, Chung wen Lan

Journal of Crystal Growth　532　2020/02/15

DOI： 10.1016/j.jcrysgro.2019.125428 　

ISSN： 0022-0248
Effect of twin boundary formation on the growth rate of the GaSb{111} plane Peer-reviewed

Keiji Shiga, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara

ACTA MATERIALIA　185　453-460　2020/02

DOI： 10.1016/j.actamat.2019.12.028 　

ISSN： 1359-6454

eISSN： 1873-2453
Influence of interfacial structure on propagating direction of small-angle grain boundaries during directional solidification of multicrystalline silicon Peer-reviewed

Lu Chung Chuang, Takanori Kiguchi, Yumiko Kodama, Kensaku Maeda, K. Shiga, Haruhiko Morito, Kozo Fujiwara

Scripta Materialia　172　105-109　2019/11

DOI： 10.1016/j.scriptamat.2019.07.018 　

ISSN： 1359-6462
Effect of misorientation angle of grain boundary on the interaction with Σ3 boundary at crystal/melt interface of multicrystalline silicon Peer-reviewed

Lu Chung Chuang, Kensaku Maeda, Haruhiko Morito, Keiji Shiga, Wolfram Miller, Kozo Fujiwara

Materialia　7　2019/09

DOI： 10.1016/j.mtla.2019.100357 　

eISSN： 2589-1529
The effect of grain boundaries on instability at the crystal/melt interface during the unidirectional growth of Si Peer-reviewed

Kuan Kan Hu, Kensaku Maeda, K. Shiga, Haruhiko Morito, Kozo Fujiwara

Materialia　7　2019/09

DOI： 10.1016/j.mtla.2019.100386 　

eISSN： 2589-1529
Crystallization and re-melting of Si<inf>1-x</inf>Ge<inf>x</inf> alloy semiconductor during rapid cooling Peer-reviewed

Mukannan Arivanandhan, Genki Takakura, D. Sidharth, Maeda Kensaku, Keiji Shiga, Haruhiko Morito, Kozo Fujiwara

Journal of Alloys and Compounds　798　493-499　2019/08/25

DOI： 10.1016/j.jallcom.2019.05.220 　

ISSN： 0925-8388
The in situ observation of faceted dendrite growth during the directional solidification of GaSb Peer-reviewed

Keiji Shiga, Masato Kawano, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara

Scripta Materialia　168　56-60　2019/07/15

DOI： 10.1016/j.scriptamat.2019.04.022 　

ISSN： 1359-6462
A {112}Σ3 grain boundary generated from the decomposition of a Σ9 grain boundary in multicrystalline silicon during directional solidification Peer-reviewed

Lu Chung Chuang, Kensaku Maeda, Keiji Shiga, Haruhiko Morito, Kozo Fujiwara

Scripta Materialia　167　46-50　2019/07/01

DOI： 10.1016/j.scriptamat.2019.03.037 　

ISSN： 1359-6462
Enhancing effects of Te substitution on the thermoelectric power factor of nanostructured SnSe<inf>1-: X</inf>Te<inf>x</inf> Peer-reviewed

D. Sidharth, A. S. Alagar Nedunchezhian, R. Rajkumar, N. Yalini Devi, P. Rajasekaran, M. Arivanandhan, K. Fujiwara, G. Anbalagan, R. Jayavel

Physical Chemistry Chemical Physics　21　(28)　15725-15733　2019

DOI： 10.1039/c9cp02018g 　

ISSN： 1463-9076
Origin of small-angle grain boundaries during directional solidification in multicrystalline silicon Peer-reviewed

Lu Chung Chuang, Kensaku Maeda, Haruhiko Morito, Keiji Shiga, Kozo Fujiwara

Materialia　3　347-352　2018/11

DOI： 10.1016/j.mtla.2018.08.034 　

eISSN： 2589-1529
Application of weighted Voronoi diagrams to analyze nucleation sites of multicrystalline silicon ingots Peer-reviewed

Tetsuro Muramatsu, Yusuke Hayama, Kentaro Kutsukake, Kensaku Maeda, Tetsuya Matsumoto, Hiroaki Kudo, Kozo Fujiwara, Noritaka Usami

Journal of Crystal Growth　499　62-66　2018/10/01

DOI： 10.1016/j.jcrysgro.2018.07.028 　

ISSN： 0022-0248
Instability of crystal/melt interface in Si-rich SiGe Peer-reviewed

M. Mokhtari, K. Fujiwara, G. Takakura, K. Maeda, H. Koizumi, J. Nozawa, S. Uda

Journal of Applied Physics　124　(8)　085104-1-085104-5　2018/08/28

DOI： 10.1063/1.5038755 　

ISSN： 0021-8979

eISSN： 1089-7550
Investigation of Si dendrites by electron-beam-induced current Peer-reviewed

Wei Yi, Jun Chen, Shun Ito, Koji Nakazato, Takashi Kimura, Takashi Sekiguchi, Kozo Fujiwara

Crystals　8　(8)　2018/08

DOI： 10.3390/cryst8080317 　

eISSN： 2073-4352
In situ observation of grain-boundary development from a facet-facet groove during solidification of silicon Peer-reviewed

Kuan Kan Hu, Kensaku Maeda, Haruhiko Morito, Keiji Shiga, Kozo Fujiwara

Acta Materialia　153　186-192　2018/07

DOI： 10.1016/j.actamat.2018.04.062 　

ISSN： 1359-6454
In-situ observation of instability of a crystal-melt interface during the directional growth of pure antimony Peer-reviewed

Keiji Shiga, Léo Billaut, Kensaku Maeda, Haruhiko Morito, Kozo Fujiwara

AIP Advances　8　(7)　2018/07/01

DOI： 10.1063/1.5038377 　

eISSN： 2158-3226
In situ observation of interaction between grain boundaries during directional solidification of Si Peer-reviewed

Lu Chung Chuang, Kensaku Maeda, Haruhiko Morito, Keiji Shiga, Wolfram Miller, Kozo Fujiwara

Scripta Materialia　148　37-41　2018/04

DOI： 10.1016/j.scriptamat.2018.01.020 　

ISSN： 1359-6462
In situ observation of grain boundary groove at the crystal/melt interface in Cu Peer-reviewed

Kensaku Maeda, Akira Niitsu, Haruhiko Morito, Keiji Shiga, Kozo Fujiwara

Scripta Materialia　146　169-172　2018/03/15

DOI： 10.1016/j.scriptamat.2017.11.039 　

ISSN： 1359-6462
In-situ studies of multicrystalline silicon nucleation and growth on α- and β-Si<inf>3</inf>N<inf>4</inf> coated substrates Peer-reviewed

Espen Undheim, Kensaku Maeda, Lars Arnberg, Randi Holmestad, Kozo Fujiwara, Marisa Di Sabatino

Journal of Crystal Growth　482　75-84　2018/01/15

DOI： 10.1016/j.jcrysgro.2017.11.005 　

ISSN： 0022-0248
Crystal Growth Conditions of Types i and II Na-Si Clathrates by Evaporation of Na from a Na-Si-Sn Solution Peer-reviewed

Haruhiko Morito, Masashi Shimoda, Hisanori Yamane, Kozo Fujiwara

Crystal Growth and Design　18　(1)　351-355　2018/01/03

DOI： 10.1021/acs.cgd.7b01342 　

ISSN： 1528-7483

eISSN： 1528-7505
Nanoscopic analysis of oxygen segregation at tilt boundaries in silicon ingots using atom probe tomography combined with TEM and ab initio calculations Peer-reviewed

Y. Ohno, K. Inoue, K. Fujiwara, K. Kutsukake, M. Deura, I. Yonenaga, N. Ebisawa, Y. Shimizu, K. Inoue, Y. Nagai, H. Yoshida, S. Takeda, S. Tanaka, M. Kohyama

Journal of Microscopy　268　(3)　230-238　2017/12

DOI： 10.1111/jmi.12602 　

ISSN： 0022-2720

eISSN： 1365-2818
Effect of an external electric field on the kinetics of dislocation-free growth of tetragonal hen egg white lysozyme crystals Peer-reviewed

Haruhiko Koizumi, Satoshi Uda, Kozo Fujiwara, Junpei Okada, Jun Nozawa

Crystals　7　(6)　2017/06/10

DOI： 10.3390/cryst7060170 　

eISSN： 2073-4352
In situ observation of twin boundary formation at grain-boundary groove during directional solidification of Si Peer-reviewed

Kozo Fujiwara, Ryoichi Maeda, Kensaku Maeda, Haruhiko Morito

Scripta Materialia　133　65-69　2017/05/01

DOI： 10.1016/j.scriptamat.2017.02.028 　

ISSN： 1359-6462
Effect of point defects on Curie temperature of lithium niobate Peer-reviewed

Chihiro Koyama, Jun Nozawa, Kozo Fujiwara, Satoshi Uda

JOURNAL OF THE AMERICAN CERAMIC SOCIETY　100　(3)　1118-1124　2017/03

DOI： 10.1111/jace.14701 　

ISSN： 0002-7820

eISSN： 1551-2916
Impact of local atomic stress on oxygen segregation at tilt boundaries in silicon Peer-reviewed

Yutaka Ohno, Kaihei Inoue, Kozo Fujiwara, Kentaro Kutsukake, Momoko Deura, Ichiro Yonenaga, Naoki Ebisawa, Yasuo Shimizu, Koji Inoue, Yasuyoshi Nagai, Hideto Yoshida, Seiji Takeda, Shingo Tanaka, Masanori Kohyama

APPLIED PHYSICS LETTERS　110　(6)　062105-062105　2017/02

DOI： 10.1063/1.4975814 　

ISSN： 0003-6951

eISSN： 1077-3118
Liquid immiscibility in a CTGS (Ca3TaGa3Si2O14) melt Peer-reviewed

Jun Nozawa, Hengyu Zhao, Chihiro Koyama, Kensaku Maeda, Kozo Fujiwara, Haruhiko Koizumi, Satoshi Uda

JOURNAL OF CRYSTAL GROWTH　454　82-86　2016/11

DOI： 10.1016/j.jcrysgro.2016.09.005 　

ISSN： 0022-0248

eISSN： 1873-5002
Technique for High-Quality Protein Crystal Growth by Control of Subgrain Formation under an External Electric Field Peer-reviewed

Haruhiko Koizumi, Satoshi Uda, Kozo Fujiwara, Masaru Tachibana, Kenichi Kojima, Jun Nozawa

CRYSTALS　6　(8)　95-1-95-14　2016/08

DOI： 10.3390/cryst6080095 　

ISSN： 2073-4352
Effect of grain boundary grooves at the crystal/melt interface on impurity accumulation during the unidirectional growth of multicrystalline silicon Peer-reviewed

Morgane Mokhtari, Kozo Fujiwara, Haruhiko Koizumi, Jun Nozawa, Satoshi Uda

SCRIPTA MATERIALIA　117　73-76　2016/05

DOI： 10.1016/j.scriptamat.2016.02.027 　

ISSN： 1359-6462
Effect of Solid-Liquid Interface Morphology on Grain Boundary Segregation during Colloidal Polycrystallization Peer-reviewed

Sumeng Hu, Jun Nozawa, Suxia Guo, Haruhiko Koizumi, Kozo Fujiwara, Satoshi Uda

CRYSTAL GROWTH & DESIGN　16　(5)　2765-2770　2016/05

DOI： 10.1021/acs.cgd.6b00066 　

ISSN： 1528-7483

eISSN： 1528-7505
Orientation-dependent impurity partitioning of colloidal crystals Peer-reviewed

Jun Nozawa, Satoshi Uda, Sumeng Hu, Kozo Fujiwara, Haruhiko Koizumi

JOURNAL OF CRYSTAL GROWTH　439　13-18　2016/04

DOI： 10.1016/j.jcrysgro.2015.12.047 　

ISSN： 0022-0248

eISSN： 1873-5002
Grain Boundary Segregation of Impurities During Polycrystalline Colloidal Crystallization Peer-reviewed

Sumeng Hu, Jun Nozawa, Haruhiko Koizumi, Kozo Fujiwara, Satoshi Uda

CRYSTAL GROWTH & DESIGN　15　(12)　5685-5692　2015/12

DOI： 10.1021/acs.cgd.5b00646 　

ISSN： 1528-7483

eISSN： 1528-7505
Crystallization of high-quality protein crystals using an external electric field Peer-reviewed

H. Koizumi, S. Uda, K. Fujiwara, M. Tachibana, K. Kojima, J. Nozawa

JOURNAL OF APPLIED CRYSTALLOGRAPHY　48　1507-1513　2015/10

DOI： 10.1107/S1600576715015885 　

ISSN： 1600-5767
Liquinert quartz crucible for the growth of multicrystalline Si ingots Peer-reviewed

Kozo Fujiwara, Yukichi Horioka, Shiro Sakuragi

ENERGY SCIENCE & ENGINEERING　3　(5)　419-422　2015/09

DOI： 10.1002/ese3.90 　

ISSN： 2050-0505
Segregation of Ge in B and Ge codoped Czochralski-Si crystal growth Peer-reviewed

Mukannan Arivanandhan, Raira Gotoh, Kozo Fujiwara, Satoshi Uda, Yasuhiro Hayakawa

JOURNAL OF ALLOYS AND COMPOUNDS　639　588-592　2015/08

DOI： 10.1016/j.jallcom.2015.03.155 　

ISSN： 0925-8388

eISSN： 1873-4669
Three-dimensional evaluation of gettering ability for oxygen atoms at small-angle tilt boundaries in Czochralski-grown silicon crystals Peer-reviewed

Yutaka Ohno, Kaihei Inoue, Kozo Fujiwara, Momoko Deura, Kentaro Kutsukake, Ichiro Yonenaga, Yasuo Shimizu, Koji Inoue, Naoki Ebisawa, Yasuyoshi Nagai

APPLIED PHYSICS LETTERS　106　(25)　251603-1-251603-4　2015/06

DOI： 10.1063/1.4921742 　

ISSN： 0003-6951

eISSN： 1077-3118
The solid-solution region for the langasite-type Ca3TaGa3Si2O14 crystal as determined by a lever rule Peer-reviewed

Hengyu Zhao, Satoshi Uda, Kensaku Maeda, Jun Nozawa, Haruhiko Koizumi, Kozo Fujiwara

JOURNAL OF CRYSTAL GROWTH　415　111-117　2015/04

DOI： 10.1016/j.jcrysgro.2014.12.042 　

ISSN： 0022-0248

eISSN： 1873-5002
17aAB-2 Oxygen segregation mechanism at small angle tilt boundaries in Si

Ohno Y., Inoue K., Fujiwara K., Deura M., Kutsukake K., Yonenaga I., Shimizu Y., Inoue K., Ebisawa N., Nagai Y.

Meeting Abstracts of the Physical Society of Japan　70　2434-2434　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.2.0_2434 　

ISSN： 2189-079X
Investigation of defect structure of impurity-doped lithium niobate by combining thermodynamic constraints with lattice constant variations Peer-reviewed

Chihiro Koyama, Jun Nozawa, Kensaku Maeda, Kozo Fujiwara, Satoshi Uda

JOURNAL OF APPLIED PHYSICS　117　(1)　014102-1-014102-7　2015/01

DOI： 10.1063/1.4905286 　

ISSN： 0021-8979

eISSN： 1089-7550
Grain Growth in the Melt Peer-reviewed

Kozo Fujiwara

Handbook of Crystal Growth: Second Edition　1　723-748　2014/12/24
Publisher: Elsevier Inc.
DOI： 10.1016/B978-0-444-56369-9.00017-4 　
Partitioning of ionic species during growth of impurity-doped lithium niobate by electric current injection Peer-reviewed

Jun Nozawa, Shintaro Iida, Chihiro Koyama, Kensaku Maeda, Kozo Fujiwara, Haruhiko Koizumi, Satoshi Uda

JOURNAL OF CRYSTAL GROWTH　406　78-84　2014/11

DOI： 10.1016/j.jcrysgro.2014.08.001 　

ISSN： 0022-0248

eISSN： 1873-5002
Control of Subgrain Formation in Protein Crystals by the Application of an External Electric Field Peer-reviewed

H. Koizumi, S. Uda, K. Fujiwara, M. Tachibana, K. Kojima, J. Nozawa

CRYSTAL GROWTH & DESIGN　14　(11)　5662-5667　2014/11

DOI： 10.1021/cg500946b 　

ISSN： 1528-7483

eISSN： 1528-7505
Crystal growth and equilibrium crystal shapes of silicon in the melt Peer-reviewed

Xinbo Yang, K. Fujiwara, K. Maeda, J. Nozawa, H. Koizumi, S. Uda

PROGRESS IN PHOTOVOLTAICS　22　(5)　574-580　2014/05

DOI： 10.1002/pip.2290 　

ISSN： 1062-7995

eISSN： 1099-159X
Instability of crystal/melt interface including twin boundaries of silicon Peer-reviewed

K. Fujiwara, M. Tokairin, W. Pan, H. Koizumi, J. Nozawa, S. Uda

APPLIED PHYSICS LETTERS　104　(18)　182110-1-182110-5　2014/05

DOI： 10.1063/1.4876177 　

ISSN： 0003-6951

eISSN： 1077-3118
Crystal Growth under External Electric Fields Peer-reviewed

Satoshi Uda, Haruhiko Koizumi, Jun Nozawa, Kozo Fujiwara

INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014)　1618　261-264　2014

DOI： 10.1063/1.4897723 　

ISSN： 0094-243X
Enhancement of Crystal Homogeneity of Protein Crystals under Application of an External Alternating Current Electric Field Peer-reviewed

H. Koizumi, S. Uda, K. Fujiwara, M. Tachibana, K. Kojima, J. Nozawa

INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014)　1618　265-268　2014

DOI： 10.1063/1.4897724 　

ISSN： 0094-243X
Grown-in microdefects and photovoltaic characteristics of heavily Ge co-doped Czochralski-grown p-type silicon crystals Peer-reviewed

Mukannan Arivanandhan, Raira Gotoh, Kozo Fujiwara, Satoshi Uda, Yasuhiro Hayakawa, Makoto Konagai

SCRIPTA MATERIALIA　69　(9)　686-689　2013/11

DOI： 10.1016/j.scriptamat.2013.07.033 　

ISSN： 1359-6462
Growth of congruent-melting lithium tantalate crystal with stoichiometric structure by MgO doping Peer-reviewed

Shunsuke Fujii, Satoshi Uda, Kensaku Maeda, Jun Nozawa, Haruhiko Koizumi, Kozo Fujiwara, Tomio Kajigaya

JOURNAL OF CRYSTAL GROWTH　383　63-66　2013/11

DOI： 10.1016/j.jcrysgro.2013.08.020 　

ISSN： 0022-0248

eISSN： 1873-5002
The effect of grain boundary characteristics on the morphology of the crystal/melt interface of multicrystalline silicon Peer-reviewed

Kozo Fujiwara, Masaya Ishii, Kensaku Maeda, Haruhiko Koizumi, Jun Nozawa, Satoshi Uda

Scripta Materialia　69　(3)　266-269　2013/08

DOI： 10.1016/j.scriptamat.2013.04.015 　

ISSN： 1359-6462
Evaluation of crystalline silicon solar cells by current-modulating four-point-probe method Peer-reviewed

Wugen Pan, Kozo Fujiwara, Satoshi Uda

APPLIED PHYSICS LETTERS　103　(4)　043903-1-043903-4　2013/07

DOI： 10.1063/1.4816783 　

ISSN： 0003-6951
Impurity Partitioning During Colloidal Crystallization International-journal Peer-reviewed

Jun Nozawa, Satoshi Uda, Yuhei Naradate, Haruhiko Koizumi, Kozo Fujiwara, Akiko Toyotama, Junpei Yamanaka

The Journal of Physical Chemistry B　117　(17)　5289-5295　2013/05/02
Publisher: American Chemical Society (ACS)
DOI： 10.1021/jp309550y 　

ISSN： 1520-6106

eISSN： 1520-5207

More details Close

We have found that an impurity partitioning takes place during growth of colloidal crystals, which was recognized by the fact that the impurity concentration in the solid (CS) was different from that in the initial solution (C0). The effective partition coefficient k(eff) (=CS/C0) was investigated for pure polystyrene and polystyrene dyed with fluorescent particles by changing the ratio of particle diameters d(imp)/d(cryst) and growth rate V. At each size ratio for the polystyrene impurity, k(eff) was less than unity and increased to unity with increasing V, whereas at a given growth rate, k(eff) increased to unity as d(imp)/d(cryst) approached unity. These results were consistent with the solute behavior analyzed using the Burton, Prim, and Slichter (BPS) model. The obtained k0, equilibrium partition coefficient, from a BPS plot increased as d(imp)/d(cryst) approached unity. In contrast, while the fluorescent particles also followed the BPS model, they showed higher k0 values than those of the same size of polystyrene particles. A k0 value greater than unity was obtained for impurities that were similar in size to the host particle. This behavior is attributed to the positive free energy of fusion associated with the incorporation of the fluorescent particles into the host matrix. Such positive free energy of fusion implies the presence of the enthalpy associated with interaction between particles.
Improvement of crystal quality for tetragonal hen egg white lysozyme crystals under application of an external alternating current electric field Peer-reviewed

H. Koizumi, S. Uda, K. Fujiwara, M. Tachibana, K. Kojima, J. Nozawa

JOURNAL OF APPLIED CRYSTALLOGRAPHY　46　25-29　2013/02

DOI： 10.1107/S0021889812048716 　

ISSN： 0021-8898

eISSN： 1600-5767
Germanium-doped Czochralski silicon: a novel material for solar cells Peer-reviewed

Mukannan Arivanandhan, Gotoh Raira, Kozo Fujiwara, Satoshi Uda, Yasuhiro Hayakawa, Makoto Konagai

PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 10, NO 12　10　(12)　1746-1749　2013

DOI： 10.1002/pssc.201300394 　

ISSN： 1862-6351
Fabrication of Quasi-Phase-Matching Structure during Paraelectric Borate Crystal Growth Peer-reviewed

Kensaku Maeda, Satoshi Uda, Kozo Fujiwara, Jun Nozawa, Haruhiko Koizumi, Shun-ichi Sato, Yuichi Kozawa, Takahiro Nakamura

APPLIED PHYSICS EXPRESS　6　(1)　015501-015501　2013/01

DOI： 10.7567/APEX.6.015501 　

ISSN： 1882-0778
Effect of silicon/crucible interfacial energy on orientation of multicrystalline silicon ingot in unidirectional growth Peer-reviewed

K. Fujiwara, K. Maeda, H. Koizumi, J. Nozawa, S. Uda

JOURNAL OF APPLIED PHYSICS　112　(11)　113521　2012/12

DOI： 10.1063/1.4769742 　

ISSN： 0021-8979
Growth velocity and grain size of multicrystalline solar cell silicon

I. Brynjulfsen, K. Fujiwara, N. Usami, L. Amberg

JOURNAL OF CRYSTAL GROWTH　356　17-21　2012/10

DOI： 10.1016/j.jcrysgro.2012.06.040 　

ISSN： 0022-0248
Nucleation rate enhancement of porcine insulin by application of an external AC electric field Peer-reviewed

H. Koizumi, Y. Tomita, S. Uda, K. Fujiwara, J. Nozawa

JOURNAL OF CRYSTAL GROWTH　352　(1)　155-157　2012/08

DOI： 10.1016/j.jcrysgro.2012.03.006 　

ISSN： 0022-0248
Crystal and faceted dendrite growth of silicon near (100) Peer-reviewed

Xinbo Yang, K. Fujiwara, R. Gotoh, K. Maeda, J. Nozawa, H. Koizumi, S. Uda

ACTA MATERIALIA　60　(8)　3259-3267　2012/05

DOI： 10.1016/j.actamat.2012.03.010 　

ISSN： 1359-6454
The Impact of Ge Codoping on the Enhancement of Minority Carrier Lifetime in B-doped Czochralski ?Grown Si Peer-reviewed

M.ARIVANANDHAN, R.GOTOH, T.WATAHIKI, K.FUJIWARA, Y.HAYAKAWA, S.UDA, M.KONAGAI

J.Applied Phys　111　043707-1　2012/04

DOI： 10.1063/1.3687935 　
Control of Gibbs free energy relationship between hen egg white lysozyme polymorphs under application of an external alternating current electric field Peer-reviewed

Y. Tomita, H. Koizumi, S. Uda, K. Fujiwara, J. Nozawa

JOURNAL OF APPLIED CRYSTALLOGRAPHY　45　(2)　207-212　2012/04

DOI： 10.1107/S002188981200249X 　

ISSN： 0021-8898
The critical growth velocity for planar-to-faceted interfaces transformation in SiGe crystals Peer-reviewed

Xinbo Yang, K. Fujiwara, N. V. Abrosimov, R. Gotoh, J. Nozawa, H. Koizumi, A. Kwasniewski, S. Uda

APPLIED PHYSICS LETTERS　100　(14)　141601　2012/04

DOI： 10.1063/1.3698336 　

ISSN： 0003-6951
The impact of Ge codoping on the enhancement of photovoltaic characteristics of B-doped Czochralski grown Si crystal Peer-reviewed

Mukannan Arivanandhan, Raira Gotoh, Tatsuro Watahiki, Kozo Fujiwara, Yasuhiro Hayakawa, Satoshi Uda, Makoto Konagai

JOURNAL OF APPLIED PHYSICS　111　(4)　043707　2012/02

DOI： 10.1063/1.3687935 　

ISSN： 0021-8979

eISSN： 1089-7550
Formation mechanism of cellular structures during unidirectional growth of binary semiconductor Si-rich SiGe materials Peer-reviewed

Raira Gotoh, Kozo Fujiwara, Xinbo Yang, Haruhiko Koizumi, Jun Nozawa, Satoshi Uda

APPLIED PHYSICS LETTERS　100　(2)　021903　2012/01

DOI： 10.1063/1.3675860 　

ISSN： 0003-6951
Boron-oxygen defect in Czochralski-silicon co-doped with gallium and boron Peer-reviewed

M. Forster, E. Fourmond, F. E. Rougieux, A. Cuevas, R. Gotoh, K. Fujiwara, S. Uda, M. Lemiti

APPLIED PHYSICS LETTERS　100　(4)　042110　2012/01

DOI： 10.1063/1.3680205 　

ISSN： 0003-6951
Crystal Growth Behaviors of Silicon during Melt Growth Processes Peer-reviewed

Kozo Fujiwara

INTERNATIONAL JOURNAL OF PHOTOENERGY　2012　169829　2012

DOI： 10.1155/2012/169829 　

ISSN： 1110-662X
Generation mechanism of dislocations and their clusters in multicrystalline silicon during two-dimensional growth Peer-reviewed

Kentaro Kutsukake, Takuro Abe, Noritaka Usami, Kozo Fujiwara, Ichiro Yonenaga, Kohei Morishita, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　110　(8)　083530-1-083530-5　2011/10

DOI： 10.1063/1.3652891 　

ISSN： 0021-8979
Formation mechanism of twin boundaries in lithium tetraborate Peer-reviewed

K. Maeda, K. Fujiwara, J. Nozawa, H. Koizumi, S. Uda

JOURNAL OF CRYSTAL GROWTH　331　(1)　78-82　2011/09

DOI： 10.1016/j.jcrysgro.2011.07.018 　

ISSN： 0022-0248
Formation mechanism of twin boundaries during crystal growth of silicon Peer-reviewed

Kentaro Kutsukake, Takuro Abe, Noritaka Usami, Kozo Fujiwara, Kohei Morishita, Kazuo Nakajima

SCRIPTA MATERIALIA　65　(6)　556-559　2011/09

DOI： 10.1016/j.scriptamat.2011.06.028 　

ISSN： 1359-6462
Control of Effect on the Nucleation Rate for Hen Egg White Lysozyme Crystals under Application of an External ac Electric Field Peer-reviewed

H. Koizumi, S. Uda, K. Fujiwara, J. Nozawa

LANGMUIR　27　(13)　8333-8338　2011/07

DOI： 10.1021/la2010985 　

ISSN： 0743-7463
Morphological transformation of a crystal-melt interface during unidirectional growth of silicon Peer-reviewed

K. Fujiwara, R. Gotoh, X. B. Yang, H. Koizumi, J. Nozawa, S. Uda

ACTA MATERIALIA　59　(11)　4700-4708　2011/06

DOI： 10.1016/j.actamat.2011.04.016 　

ISSN： 1359-6454
Plastically deformed Si-crystal wafers for neutron-monochromator elements Peer-reviewed

H. Hiraka, K. Fujiwara, K. Yamada, K. Morishita, K. Nakajima

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT　635　(1)　137-140　2011/04

DOI： 10.1016/j.nima.2011.01.168 　

ISSN： 0168-9002
Implementation of faceted dendrite growth on floating cast method to realize high-quality multicrsytalline Si ingot for solar cells

Noritaka Usami, Isao Takahashi, Kentaro Kutsukake, Kozo Fujiwara, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　109　(8)　2011/04

DOI： 10.1063/1.3576108 　

ISSN： 0021-8979
Dependence of Si-Faceted Dendrite Growth Orientation on Twin Spacing and Undercooling Peer-reviewed

Xinbo Yang, K. Fujiwara, K. Maeda, J. Nozawa, H. Koizumi, S. Uda

CRYSTAL GROWTH & DESIGN　11　(4)　1402-1410　2011/04

DOI： 10.1021/cg101721v 　

ISSN： 1528-7483
The impact of Ge codoping on grown-in O precipitates in Ga-doped Czochralski-silicon Peer-reviewed

Mukannan Arivanandhan, Raira Gotoh, Kozo Fujiwara, Tetsuo Ozawa, Yasuhiro Hayakawa, Satoshi Uda

JOURNAL OF CRYSTAL GROWTH　321　(1)　24-28　2011/04

DOI： 10.1016/j.jcrysgro.2011.02.028 　

ISSN： 0022-0248

eISSN： 1873-5002
Dependence of Si faceted dendrite growth velocity on undercooling Peer-reviewed

Yang Xinbo, Kozo Fujiwara, Kensaku Maeda, Jun Nozawa, Haruhiko Koizumi, Satoshi Uda

Appl. Phys. Lett.　98　(4)　012113-1410　2011

DOI： 10.1021/cg101721v 　
Dependence of Si faceted dendrite growth velocity on undercooling Peer-reviewed

Xinbo Yang, K. Fujiwara, K. Maeda, J. Nozawa, H. Koizumi, S. Uda

APPLIED PHYSICS LETTERS　98　(1)　012113 -1-012113 -3　2011/01

DOI： 10.1063/1.3543623 　

ISSN： 0003-6951
Pattern formation mechanism of a periodically faceted interface during crystallization of Si Peer-reviewed

M. Tokairin, K. Fujiwara, K. Kutsukake, H. Kodama, N. Usami, K. Nakajima

JOURNAL OF CRYSTAL GROWTH　312　(24)　3670-3674　2010/12

DOI： 10.1016/j.jcrysgro.2010.09.059 　

ISSN： 0022-0248
Effect of various precipitants on the nucleation rate of tetragonal hen egg-white lysozyme crystals in an AC external electric field Peer-reviewed

H. Koizumi, S. Uda, K. Fujiwara, J. Nozawa

JOURNAL OF CRYSTAL GROWTH　312　(23)　3503-3508　2010/11

DOI： 10.1016/j.jcrysgro.2010.09.006 　

ISSN： 0022-0248
Ga segregation during Czochralski-Si crystal growth with Ge codoping Peer-reviewed

Raira Gotoh, M. Arivanandhan, Kozo Fujiwara, Satoshi Uda

JOURNAL OF CRYSTAL GROWTH　312　(20)　2865-2870　2010/10

DOI： 10.1016/j.jcrysgro.2010.07.007 　

ISSN： 0022-0248

eISSN： 1873-5002
Effect of twin spacing on the growth velocity of Si faceted dendrites Peer-reviewed

Xinbo Yang, Kozo Fujiwara, Raira Gotoh, Kensaku Maeda, Jun Nozawa, Haruhiko Koizumi, Satoshi Uda

APPLIED PHYSICS LETTERS　97　(17)　172104　2010/10

DOI： 10.1063/1.3501974 　

ISSN： 0003-6951
Role of the Electric Double Layer in Controlling the Nucleation Rate for Tetragonal Hen Egg White Lysozyme Crystals by Application of an External Electric Field Peer-reviewed

H. Koizumi, K. Fujiwara, S. Uda

CRYSTAL GROWTH & DESIGN　10　(6)　2591-2595　2010/06

DOI： 10.1021/cg901621x 　

ISSN： 1528-7483
Growth mechanism of the Si < 110 > faceted dendrite Peer-reviewed

K. Fujiwara, H. Fukuda, N. Usami, K. Nakajima, S. Uda

PHYSICAL REVIEW B　81　(22)　224106　2010/06

DOI： 10.1103/PhysRevB.81.224106 　

ISSN： 1098-0121
Relationship between grain boundary structures in Si multicrystals and generation of dislocations during crystal growth Peer-reviewed

Noritaka Usami, Ryusuke Yokoyama, Isao Takahashi, Kentaro Kutsukake, Kozo Fujiwara, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　107　(1)　013511　2010/01

DOI： 10.1063/1.3276219 　

ISSN： 0021-8979
Realization of a High-Performance Point-Focusing Monochromator for X-ray Studies Peer-reviewed

Hiroshi Okuda, Kohei Morishita, Kazuo Nakajima, Kozo Fujiwara, Ichiro Yonenaga, Shojiro Ochiai

APPLIED PHYSICS EXPRESS　3　(4)　046601　2010

DOI： 10.1143/APEX.3.046601 　

ISSN： 1882-0778
Growth behavior of faceted Si crystals at grain boundary formation Peer-reviewed

K. Fujiwara, S. Tsumura, M. Tokairin, K. Kutsukake, N. Usami, S. Uda, K. Nakajima

JOURNAL OF CRYSTAL GROWTH　312　(1)　19-23　2009/12

DOI： 10.1016/j.jcrysgro.2009.09.055 　

ISSN： 0022-0248
Formation mechanism of a faceted interface: In situ observation of the Si(100) crystal-melt interface during crystal growth Peer-reviewed

M. Tokairin, K. Fujiwara, K. Kutsukake, N. Usami, K. Nakajima

PHYSICAL REVIEW B　80　(17)　174108-1-174108-4　2009/11

DOI： 10.1103/PhysRevB.80.174108 　

ISSN： 1098-0121
Systematic studies of Si and Ge hemispherical concave wafers prepared by plastic deformation Peer-reviewed

Kazuo Nakajima, Kozo Fujiwara, Kohei Morishita

Journal of Crystal Growth　311　(21)　4587-4592　2009/10/15

DOI： 10.1016/j.jcrysgro.2009.08.021 　

ISSN： 0022-0248
Effects of B and Ge codoping on minority carrier lifetime in Ga-doped Czochralski-silicon Peer-reviewed

Mukannan Arivanandhan, Raira Gotoh, Kozo Fujiwara, Satoshi Uda

JOURNAL OF APPLIED PHYSICS　106　(1)　013721　2009/07

DOI： 10.1063/1.3159038 　

ISSN： 0021-8979

eISSN： 1089-7550
Microstructures of Si multicrystals and their impact on minority carrier diffusion length Peer-reviewed

H. Y. Wang, N. Usami, K. Fujiwara, K. Kutsukake, K. Nakajima

ACTA MATERIALIA　57　(11)　3268-3276　2009/06

DOI： 10.1016/j.actamat.2009.03.033 　

ISSN： 1359-6454
Control of Nucleation Rate for Tetragonal Hen-Egg White Lysozyme Crystals by Application of an Electric Field with Variable Frequencies Peer-reviewed

H. Koizumi, K. Fujiwara, S. Uda

CRYSTAL GROWTH & DESIGN　9　(5)　2420-2424　2009/05

DOI： 10.1021/cg801315p 　

ISSN： 1528-7483
High minority carrier lifetime in Ga-doped Czochralski-grown silicon by Ge codoping Peer-reviewed

Mukannan Arivanandhan, Raira Gotoh, Kozo Fujiwara, Satoshi Uda

APPLIED PHYSICS LETTERS　94　(7)　072102　2009/02

DOI： 10.1063/1.3085959 　

ISSN： 0003-6951

eISSN： 1077-3118
Quantitative analysis of subgrain boundaries in Si multicrystals and their impact on electrical properties and solar cell performance Peer-reviewed

Kentaro Kutsukake, Noritaka Usami, Tsuyoshi Ohtaniuchi, Kozo Fujiwara, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　105　(4)　044909　2009/02

DOI： 10.1063/1.3079504 　

ISSN： 0021-8979
Novel ultra-lightweight and high-resolution MEMS X-ray optics

Ikuyuki Mitsuishi, Yuichiro Ezoe, Utako Takagi, Makoto Mita, Raul Riveros, Hitomi Yamaguchi, Fumiki Kato, Susumu Sugiyama, Kouzou Fujiwara, Kohei Morishita, Kazuo Nakajima, Shinya Fujihira, Yoshiaki Kanamori, Noriko Y. Yamasaki, Kazuhisa Mitsuda, Ryutaro Maeda

EUV AND X-RAY OPTICS: SYNERGY BETWEEN LABORATORY AND SPACE　7360　73600C-1-73600C-9　2009

DOI： 10.1117/12.823933 　

ISSN： 0277-786X
Development of high-resolution and light-weight x-ray optics with deformed silicon wafers

Yuichiro Ezoe, Takayuki Shirata, Takaya Ohashi, Manabu Ishida, Kazuhisa Mitsuda, Kozo Fujiwara, Kohei Morishita, Kazuo Nakajima

EUV AND X-RAY OPTICS: SYNERGY BETWEEN LABORATORY AND SPACE　7360　2009

DOI： 10.1117/12.823932 　

ISSN： 0277-786X
M. Arivanandhan, R. Gotoh, K. Fujiwara and S. Uda Peer-reviewed

M. Arivanandhan, R. Gotoh, K. Fujiwara, S. Uda

Appl. Phys. Lett.　94　072102　2009
Floating cast method to realize high-quality Si bulk multicrystals for solar cells Peer-reviewed

Yoshitaro Nose, Isao Takahashi, Wugen Pan, Noritaka Usami, Kozo Fujiwara, Kazuo Nakajima

JOURNAL OF CRYSTAL GROWTH　311　(2)　228-231　2009/01

DOI： 10.1016/j.jcrysgro.2008.10.098 　

ISSN： 0022-0248
Impact of Defect Density in Si Bulk Multicrystals on Gettering Effect of Impurities Peer-reviewed

Isao Takahashi, Noritaka Usami, Ryusuke Yokoyama, Yoshitaro Nose, Kentaro Kutuskake, Kozo Fuilwara, Kazuo Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS　47　(12)　8790-8792　2008/12

DOI： 10.1143/JJAP.47.8790 　

ISSN： 0021-4922
Influence of growth temperature and cooling rate on the growth of Si epitaxial layer by dropping-type liquid phase epitaxy from the pure Si melt Peer-reviewed

Zengmei Wang, Kentaro Kutsukake, Hitoshi Kodama, Noritaka Usami, Kozo Fujiwara, Yoshitaro Nose, Kazuo Nakajima

JOURNAL OF CRYSTAL GROWTH　310　(24)　5248-5251　2008/12

DOI： 10.1016/j.jcrysgro.2008.08.063 　

ISSN： 0022-0248
Point-focusing monochromator crystal realized by hot plastic deformation of a Ge wafer International-journal Peer-reviewed

Hiroshi Okuda, Kazuo Nakajima, Kozo Fujiwara, Kohei Morishita, Shojiro Ochiai

JOURNAL OF APPLIED CRYSTALLOGRAPHY　41　(Pt 4)　798-799　2008/08

DOI： 10.1107/S0021889808016282 　

ISSN： 0021-8898
Growth mechanism of Si-faceted dendrites Peer-reviewed

K. Fujiwara, K. Maeda, N. Usami, K. Nakajima

PHYSICAL REVIEW LETTERS　101　(5)　055503　2008/08

DOI： 10.1103/PhysRevLett.101.055503 　

ISSN： 0031-9007
Structural origin of a cluster of bright spots in reverse bias electroluminescence image of solar cells based on Si multicrystals Peer-reviewed

Noritaka Usami, Kentaro Kutsukake, Kozo Fujiwara, Ichiro Yonenaga, Kazuo Nakajima

APPLIED PHYSICS EXPRESS　1　(7)　075001　2008/07

DOI： 10.1143/APEX.1.075001 　

ISSN： 1882-0778
In situ observation of Si faceted dendrite growth from low-degree-of-undercooling melts Peer-reviewed

Kozo Fujiwara, Kensaku Maeda, Noritaka Usami, Gen Sazaki, Yoshitaro Nose, Akiko Nomura, Toetsu Shishido, Kazuo Nakajima

ACTA MATERIALIA　56　(11)　2663-2668　2008/06

DOI： 10.1016/j.actamat.2008.01.038 　

ISSN： 1359-6454
Wave-dispersive x-ray spectrometer for simultaneous acquisition of several characteristic lines based on strongly and accurately shaped Ge crystal International-journal Peer-reviewed

Kouichi Hayashi, Kazuo Nakajima, Kozo Fujiwara, Susumu Nishikata

REVIEW OF SCIENTIFIC INSTRUMENTS　79　(3)　033110-033110　2008/03

DOI： 10.1063/1.2898406 　

ISSN： 0034-6748
Floating Cast Method as a New Growth Method of Silicon Bulk Multicrystals for Solar Cells Peer-reviewed

I. Takahashi, Y. Nose, N. Usami, K. Fujiwara, E. Nakajima

FRONTIERS IN MATERIALS RESEARCH　10　149-156　2008

ISSN： 1435-1889
High-Quality Si Multicrystals with Same Grain Orientation and Large Grain Size by the Newly Developed Dendritic Casting Method for High-Efficiency Solar Cell Applications Peer-reviewed

K. Nakajima, K. Fujiwara, N. Usami

FRONTIERS IN MATERIALS RESEARCH　10　123-+　2008

ISSN： 1435-1889
Growth of High-Quality Polycrystalline Si Ingot with Same Grain Orientation by Using Dendritic Casting Method Peer-reviewed

K. Fujiwara, W. Pan, N. Usami, A. Tokairin, Y. Nose, A. Nomura, T. Shishido, K. Nakajima

FRONTIERS IN MATERIALS RESEARCH　10　141-+　2008

ISSN： 1435-1889
Modification of local structures in multicrystals revealed by spatially resolved x-ray rocking curve analysis

Noritaka Usami, Kentaro Kutsukake, Kozo Fujiwara, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　102　(10)　2007/11

DOI： 10.1063/1.2816207 　

ISSN： 0021-8979
Formation mechanism of parallel twins related to Si-facetted dendrite growth Peer-reviewed

K. Fujiwara, K. Maeda, N. Usami, G. Sazaki, Y. Nose, K. Nakajima

SCRIPTA MATERIALIA　57　(2)　81-84　2007/07

DOI： 10.1016/j.scriptamat.2007.03.052 　

ISSN： 1359-6462
Improvement in the conversion efficiency of single-junction SiGe solar cells by intentional introduction of the compositional distribution Peer-reviewed

Misumi Tayanagi, Noritaka Usami, Wugen Pan, Keisuke Ohdaira, Kozo Fujiwara, Yoshitaro Nose, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　101　(5)　054504　2007/03

DOI： 10.1063/1.2709575 　

ISSN： 0021-8979
Influence of structural imperfection of Sigma 5 grain boundaries in bulk multicrystalline Si on their electrical activities Peer-reviewed

Kentaro Kutsukake, Noritaka Usami, Kozo Fujiwara, Yoshitaro Nose, Kazuo Nakajima

JOURNAL OF APPLIED PHYSICS　101　(6)　063509　2007/03

DOI： 10.1063/1.2710348 　

ISSN： 0021-8979
Modification of local structure and its influence on electrical activity of near (310) Sigma 5 grain boundary in bulk silicon Peer-reviewed

Kentaro Kutsukake, Noritaka Usami, Kozo Fujiwara, Yoshitaro Nose, Takamasa Sugawara, Toetsu Shishido, Kazuo Nakajima

MATERIALS TRANSACTIONS　48　(2)　143-147　2007/02

DOI： 10.2320/matertrans.48.143 　

ISSN： 1345-9678

eISSN： 1347-5320
Effect of the compositional distribution on the photovoltaic power conversion of SiGe solar cells Peer-reviewed

Noritaka Usami, Wugen Pan, Kozo Fujiwara, Misumi Tayanagi, Keisuke Ohdaira, Kazuo Nakajima

SOLAR ENERGY MATERIALS AND SOLAR CELLS　91　(2-3)　123-128　2007/01

DOI： 10.1016/j.solmat.2006.07.006 　

ISSN： 0927-0248
Molten metal flux growth and study of properties and chemical state of a new compound PrRh4.8B2 Peer-reviewed

T. Shishido, M. Oku, S. Okada, N. Nogi, T. Amano, J. Ye, T. Mori, M. Tanaka, K. Shimamura, A. Yoshikawa, R. Sahara, K. Yubuta, V. Kumar, A. Nomura, T. Sugawara, S. Tozawa, K. Obara, N. Ohtsu, K. Hayashi, K. Fuijiwara, N. Usami, S. Kohiki, K. Teshima, S. Oishi, Y. Kawazoe, K. Nakajima

J. Flux Growth　2　87-92　2007
Directional growth method to obtain high quality polycrystalline silicon from its melt Peer-reviewed

K. Fujiwara, W. Pan, K. Sawada, M. Tokairin, N. Usami, Y. Nose, A. Nomura, T. Shishido, K. Nakajima

JOURNAL OF CRYSTAL GROWTH　292　(2)　282-285　2006/07

DOI： 10.1016/j.jcrysgro.2006.04.016 　

ISSN： 0022-0248
Growth of structure-controlled polycrystalline silicon ingots for solar cells by casting Peer-reviewed

Kozo Fujiwara, Wugen Pan, Noritaka Usami, Kohei Sawada, Masatoshi Tokairin, Yoshitaro Nose, Akiko Nomura, Toetsu Shishido, Kazuo Nakajima

ACTA MATERIALIA　54　(12)　3191-3197　2006/07

DOI： 10.1016/j.actamat.2006.03.014 　

ISSN： 1359-6454
Si wafers having one- and two-dimensionally curved (111) planes examined by X-ray diffraction Peer-reviewed

Hiroshi Okuda, Kazuo Nakajima, Kozo Fujiwara, Shojiro Ochiai

Journal of Applied Crystallography　39　(3)　443-445　2006/06

DOI： 10.1107/S0021889806011939 　

ISSN： 0021-8898 1600-5767
Intermixing of Ge and Si during exposure of GeH4 on Si Peer-reviewed

G Watari, N Usami, Y Nose, K Fujiwara, G Sazaki, K Nakajima

THIN SOLID FILMS　508　(1-2)　163-165　2006/06

DOI： 10.1016/j.tsf.2005.08.403 　

ISSN： 0040-6090
Suppression of structural imperfection in strained Si by utilizing SiGe bulk substrate Peer-reviewed

N Usami, Y Nose, K Fujiwara, K Nakajima

APPLIED PHYSICS LETTERS　88　(22)　2006/05

DOI： 10.1063/1.2208928 　

ISSN： 0003-6951
Realization of bulk multicrystalline silicon with controlled grain boundaries by utilizing spontaneous modification of grain boundary configuration Peer-reviewed

N Usami, K Kutsukake, T Sugawara, K Fujwara, W Pan, Y Nose, T Shishido, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　45　(3A)　1734-1737　2006/03

DOI： 10.1143/JJAP.45.1734 　

ISSN： 0021-4922
High-efficiency concave and conventional solar cell integration system using focused reflected light Peer-reviewed

K Ohdaira, K Fujiwara, W Pan, N Usami, K Nakajiima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　45　(3A)　1664-1667　2006/03

DOI： 10.1143/JJAP.45.1664 　

ISSN： 0021-4922
Suppression of structural imperfection in strained Si thin film by utilizing SiGe bulk substrate Peer-reviewed

Noritaka Usami, Yoshitaro Nose, Kozo Fujiwara, Kazuo Nakajima

ECS Transactions　3　(7)　299-302　2006

DOI： 10.1149/1.2355825 　

ISSN： 1938-5862 1938-6737
Development of textured high-quality Si and SiGe multicrystal ingots with same grain orientation and large grain sizes by the new dendritic casting method Peer-reviewed

Kazuo Nakajima, Kozo Fujiwara, Masatoshi Tokairin, Wugen Pan, Yoshitaro Nose, Noritaka Usami

ECS Transactions　3　(7)　265-267　2006

DOI： 10.1149/1.2355820 　

ISSN： 1938-5862 1938-6737
Analysis of the dark-current density in solar cells based on multicrystalline SiGe Peer-reviewed

K Ohdaira, N Usami, WG Pan, K Fujiwara, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　44　(11)　8019-8022　2005/11

DOI： 10.1143/JJAP.44.8019 　

ISSN： 0021-4922
Influence of growth temperature on minority-carrier lifetime of Si layer grown by liquid phase epitaxy using Ga solvent Peer-reviewed

Y Satoh, N Usami, W Pan, K Fujiwara, K Nakajima, T Ujihara

JOURNAL OF APPLIED PHYSICS　98　(7)　703-708　2005/10

DOI： 10.1063/1.2061891 　

ISSN： 0021-8979

eISSN： 1089-7550
Solar cell system using a polished concave Si-crystal mirror Peer-reviewed

K Nakajima, K Ohdaira, K Fujiwara, WG Pan

SOLAR ENERGY MATERIALS AND SOLAR CELLS　88　(3)　323-329　2005/08

DOI： 10.1016/j.solmat.2005.03.012 　

ISSN： 0927-0248
Hemisphere-shaped silicon crystal wafers obtained by plastic deformation and preparation of their solar cells Peer-reviewed

K Nakajima, K Fujiwara, WG Pan

JOURNAL OF ELECTRONIC MATERIALS　34　(7)　1047-1052　2005/07

DOI： 10.1007/s11664-005-0094-5 　

ISSN： 0361-5235
Liquid phase epitaxial growth of Si layers on Si thin substrates from Si pure melts under near-equilibrium conditions Peer-reviewed

K Nakajima, K Fujiwara, Y Nose, N Usami

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　44　(7A)　5092-5095　2005/07

DOI： 10.1143/JJAP.44.5092 　

ISSN： 0021-4922
Growth of multicrystalline Si with controlled grain boundary configuration by the floating zone technique Peer-reviewed

M Kitamura, N Usami, T Sugawara, K Kutsukake, K Fujiwara, Y Nose, T Shishido, K Nakajima

JOURNAL OF CRYSTAL GROWTH　280　(3-4)　419-424　2005/07

DOI： 10.1016/j.jcrysgro.2005.04.049 　

ISSN： 0022-0248
Control of compound forming reaction at the interface between SnZn solder and Cu substrate Peer-reviewed

Ichitsubo, T, Matsubara, E, Fujiwara, K, al

Journal of Alloys and Compounds　2005/04/19

DOI： 10.1016/j.jallcom.2004.09.043 　
Crystal quality of a 6H-SiC layer grown over macrodefects by liquid-phase epitaxy: a Raman spectroscopic study Peer-reviewed

T Ujihara, S Munetoh, K Kusunoki, K Kamei, N Usami, K Fujiwara, G Sazaki, K Nakajima

THIN SOLID FILMS　476　(1)　206-209　2005/04

DOI： 10.1016/j.tsf.2004.09.039 　

ISSN： 0040-6090
A simple approach to determine preferential growth orientation using multiple seed crystals with random orientations and its utilization for seed optimization to restrain polycrystallization of SiGe bulk crystal Peer-reviewed

Y Azuma, N Usami, K Fujiwara, T Ujihara, K Nakajima

JOURNAL OF CRYSTAL GROWTH　276　(3-4)　393-400　2005/04

DOI： 10.1016/j.jcrysgro.2004.11.430 　

ISSN： 0022-0248
Structural properties of directionally grown polycrystalline SiGe for solar cells Peer-reviewed

K Fujiwara, W Pan, N Usami, K Sawada, A Nomura, T Ujihara, T Shishido, K Nakajima

JOURNAL OF CRYSTAL GROWTH　275　(3-4)　467-473　2005/03

DOI： 10.1016/j.jcrysgro.2004.12.023 　

ISSN： 0022-0248

eISSN： 1873-5002
Growth of SiGe-on-insulator and its application as a substrate for epitaxy of strained-Si layer Peer-reviewed

Noritaka Usami, Kentaro Kutsukake, Wugen Pan, Kozo Fujiwara, Toru Ujihara, Baoping Zhang, Takashi Yokoyama, Kazuo Nakajima

JOURNAL OF CRYSTAL GROWTH　275　(1-2)　E1203-E1207　2005/02

DOI： 10.1016/j.jcrysgro.2004.11.141 　

ISSN： 0022-0248

eISSN： 1873-5002
Growth and properties of SiGe multicrystals with microscopic compositional distribution and their applications for high-efficiency solar cells Peer-reviewed

Kazuo Nakajima, Kozo Fujiwara, Wugen Pan, Noritaka Usami, Toetsu Shishido

JOURNAL OF CRYSTAL GROWTH　275　(1-2)　E455-E460　2005/02

DOI： 10.1016/j.jcrysgro.2004.11.019 　

ISSN： 0022-0248
On the origin of improved conversion efficiency of solar cells based on SiGe with compositional distribution Peer-reviewed

N Usami, K Fujiwara, WG Pan, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　44　(2)　857-860　2005/02

DOI： 10.1143/JJAP.44.857 　

ISSN： 0021-4922
Growth of InGaAs and SiGe homogeneous bulk crystals which have complete miscibility in the phase diagrams Peer-reviewed

K Nakajima, Y Azuma, N Usami, G Sazaki, T Ujihara, K Fujiwara, T Shishido, Y Nishijima, T Kusunoki

INTERNATIONAL JOURNAL OF MATERIALS & PRODUCT TECHNOLOGY　22　(1-3)　185-212　2005

DOI： 10.1504/IJMPT.2005.005764 　

ISSN： 0268-1900
Shaped silicon-crystal wafers obtained by plastic deformation and their application to silicon-crystal lenses Peer-reviewed

K Nakajima, K Fujiwara, WG Pan, H Okuda

NATURE MATERIALS　4　(1)　47-50　2005/01

DOI： 10.1038/nmat1282 　

ISSN： 1476-1122
Effects of vicinal steps on the island growth and orientation of epitaxially grown perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) thin film crystals on a hydrogen-terminated Si(111) substrate Peer-reviewed

G Sazaki, T Fujino, N Usami, T Ujihara, K Fujiwara, K Nakajima

JOURNAL OF CRYSTAL GROWTH　273　(3-4)　594-602　2005/01

DOI： 10.1016/j.jcrysgro.2004.09.082 　

ISSN： 0022-0248

eISSN： 1873-5002
Floating zone growth of Si bicrystals using seed crystals with artificially designed grain boundary configuration Peer-reviewed

N Usami, M Kitamura, T Sugawara, K Kutsukake, K Ohdaira, Y Nose, K Fujiwara, T Shishido, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS　44　(24-27)　L778-L780　2005

DOI： 10.1143/JJAP.44.L778 　

ISSN： 0021-4922
Wave-shaped Si crystal wafers obtained by plastic deformation and preparation of their solar cells Peer-reviewed

K Nakajima, K Fujiwara, WG Pan

APPLIED PHYSICS LETTERS　85　(24)　5896-5898　2004/12

DOI： 10.1063/1.1834719 　

ISSN： 0003-6951
Molten metal flux growth and properties of CrSi2 Peer-reviewed

T Shishido, S Okada, Y Ishizawa, K Kudou, K Iizumi, Y Sawada, H Horiuchi, K Inaba, T Sekiguchi, J Ye, S Miyashita, A Nomura, T Sugawara, K Obara, M Oku, K Fujiwara, T Ujihara, G Sazaki, N Usami, S Kohiki, Y Kawazoe, K Nakajima

JOURNAL OF ALLOYS AND COMPOUNDS　383　(1-2)　319-321　2004/11

DOI： 10.1016/j.jallcom.2004.04.037 　

ISSN： 0925-8388
On the origin of strain fluctuation in strained-Si grown on SiGe-on-insulator and SiGe virtual substrates Peer-reviewed

K Kutsukake, N Usami, T Ujihara, K Fujiwara, G Sazaki, K Nakajima

APPLIED PHYSICS LETTERS　85　(8)　1335-1337　2004/08

DOI： 10.1063/1.1784036 　

ISSN： 0003-6951

eISSN： 1077-3118
Successful growth of InxGa1-xAs (x > 0.18) single bulk crystal directly on GaAs seed crystal with preferential orientation Peer-reviewed

Y Azuma, Y Nishijima, K Nakajima, N Usami, K Fujiwara, T Ujihara

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS　43　(7A)　L907-L909　2004/07

DOI： 10.1143/JJAP.43.L907 　

ISSN： 0021-4922
Ge composition dependence of properties of solar cells based on multicrystalline SiGe with microscopic compositional distribution Peer-reviewed

WG Pan, K Fujiwara, N Usami, T Ujihara, K Nakajima, R Shimokawa

JOURNAL OF APPLIED PHYSICS　96　(2)　1238-1241　2004/07

DOI： 10.1063/1.1763227 　

ISSN： 0021-8979
Effects of growth temperature on the surface morphology of silicon thin films on (111) silicon monocrystalline substrate by liquid phase epitaxy Peer-reviewed

T Ujihara, E Kanda, K Obara, K Fujiwara, N Usami, G Sazaki, A Alguno, T Shishido, K Nakajima

JOURNAL OF CRYSTAL GROWTH　266　(4)　467-474　2004/06

DOI： 10.1016/j.jcrysgro.2003.12.081 　

ISSN： 0022-0248
Grain growth behaviors of polycrystalline silicon during melt growth processes Peer-reviewed

K Fujiwara, Y Obinata, T Ujihara, N Usami, G Sazaki, K Nakajima

JOURNAL OF CRYSTAL GROWTH　266　(4)　441-448　2004/06

DOI： 10.1016/j.jcrysgro.2004.03.008 　

ISSN： 0022-0248
Effects of spacer thickness on quantum efficiency of the solar cells with embedded Ge islands in the intrinsic layer Peer-reviewed

A Alguno, N Usami, T Ujihara, K Fujiwara, G Sazaki, K Nakajima, K Sawano, Y Shiraki

APPLIED PHYSICS LETTERS　84　(15)　2802-2804　2004/04

DOI： 10.1063/1.1697632 　

ISSN： 0003-6951
Fabrication of SiGe-on-insulator by rapid thermal annealing of Ge on Si-on-insulator substrate Peer-reviewed

K Kutsukake, N Usami, K Fujiwara, T Ujihara, G Sazaki, K Nakajima, BP Zhang, Y Segawa

APPLIED SURFACE SCIENCE　224　(1-4)　95-98　2004/03

DOI： 10.1016/j.apsusc.2003.08.100 　

ISSN： 0169-4332
Fabrication of solar cell with stacked Ge islands for enhanced absorption in the infrared regime Peer-reviewed

N Usami, A Alguno, K Sawano, T Ujihara, K Fujiwara, G Sazaki, Y Shiraki, K Nakajima

THIN SOLID FILMS　451　604-607　2004/03

DOI： 10.1016/j.tsf.2003.11.027 　

ISSN： 0040-6090
In-situ observations of melt growth behavior of polycrystalline silicon Peer-reviewed

K Fujiwara, Y Obinata, T Ujhara, N Usami, G Sazaki, K Nakajima

JOURNAL OF CRYSTAL GROWTH　262　(1-4)　124-129　2004/02

DOI： 10.1016/j.jcrysgro.2003.10.075 　

ISSN： 0022-0248
Epitaxial relation and island growth of perylene-3.4.9.10-tetracarboxylic dianhydride (PTCDA) thin film crystals on a hydrogen-terminated Si(111) substrate Peer-reviewed

G Sazaki, T Fujino, JT Sadowski, N Usami, T Ujihara, K Fujiwara, Y Takahashi, E Matsubara, T Sakurai, K Nakajima

JOURNAL OF CRYSTAL GROWTH　262　(1-4)　196-201　2004/02

DOI： 10.1016/j.jcrysgro.2003.08.080 　

ISSN： 0022-0248
In situ observation of elementary growth steps on the surface of protein crystals by laser confocal microscopy Peer-reviewed

G Sazaki, T Matsui, K Tsukamoto, N Usami, T Ujihara, K Fujiwara, K Nakajima

JOURNAL OF CRYSTAL GROWTH　262　(1-4)　536-542　2004/02

DOI： 10.1016/j.jcrysgro.2003.10.049 　

ISSN： 0022-0248
Relationship between device performance and grain boundary structural configuration in a solar cell based on multicrystalline SiGe Peer-reviewed

N. Usami, W. Pan, K. Fujiwara, T. Ujihara, G. Sazaki, K. Nakajima

Jpn. J. Appl. Phys.　43　(2)　250-252　2004/01/20
Publisher: INSTITUTE OF PURE AND APPLIED PHYSICS
DOI： 10.1143/JJAP.43.L250 　

ISSN： 0021-4922

More details Close

The grain boundary character distribution of multicrystalline SiGe (mc-SiGe) solar cells with microscopic compositional distribution was revealed to have a significant effect on the photovoltaic performance of solar cells. This was clarified by comparing the photovoltaic performance of small-area (${\approx}0.02$ cm2) solar cells fabricated in a large-area solar cell with their local structures. With increasing fraction of random grain boundaries in a small-area solar cell, the conversion efficiency was found to decrease. On the other hand, $\Sigma 3$ grain boundaries are found to be dominant in a solar cell with good performance. These results suggest that the development of a crystal growth technique that fully controls the grain boundary character distribution is the key to improving the conversion efficiency of the solar cell based on multicrystalline semiconductors.
Improvement of device performance of multicrystalline Si-based solar cells using multicrystalline SiGe with microscopic compositional distribution

Kazuo Nakajima, Kozo Fujiwara, Wugen Pan, Noritaka Usami, Toru Ujihara, Toetsu Shishido

Proceedings - Electrochemical Society　7　1059-1065　2004
Improved photovoltaic cell performance based on Ge islands embedded into the intrinsic layer

Arnold Alguno, Noritaka Usami, Wugen Pan, Kentaro Sawano, Kozo Fujiwara, Toru Ujihara, Yasuhiro Shiraki, Takashi Yokoyama, Kazuo Nakajima

Proceedings - Electrochemical Society　7　1067-1076　2004
New solar cells using Ge dots embedded in SiPIN structures Peer-reviewed

N Usami, A Arnold, K Fujiwara, K Nakajima, T Yokoyama, Y Shiraki

2004 IST IEEE INTERNATIONAL CONFERENCE ON GROUP IV PHOTONICS　130-132　2004
Excellent Effect of Gallium Solvent on Preparation of High Lifetime Silicon Crystal by LPE Method Peer-reviewed

Toru Ujihara, Yusuke Satoh, Kazuo Obara, Kozo Fujiwara, Gen Sazaki, Noritaka Usami, Toetsu Shishido, Kazuo Nakajima

?　2004
SiGeバルク単結晶と多結晶の成長技術およびそれらのデバイス応用 : 均一組成のバルク単結晶とミクロ分散的組成分布を有する太陽電池用バルク多結晶

中嶋一雄, 藤原航三, 宇佐美徳隆, 藩伍根, 佐崎元, 宇治原徹, 宍戸統悦

日本結晶成長学会誌　31　29-37　2004
Crystal quality evaluation of 6H-SiC layers grown by liquid phase epitaxy around micropipes using micro-Raman scattering spectroscopy

T Ujihara, S Munetoh, K Kusunoki, K Kamei, N Usami, K Fujiwara, G Sazaki, K Nakajima

SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2　457-460　633-636　2004

ISSN： 0255-5476
Phase diagram of growth mode for the SiGe/Si heterostructure system with misfit dislocations Peer-reviewed

K Nakajima, T Ujihara, N Usami, K Fujiwara, G Sazaki, T Shishido

JOURNAL OF CRYSTAL GROWTH　260　(3-4)　372-383　2004/01

DOI： 10.1016/j.jcrysgro.2003.08.069 　

ISSN： 0022-0248
High-temperature solution growth and characterization of chromium disilicide Peer-reviewed

T Shishido, S Okada, Y Ishizawa, K Kudou, K Iizumi, Y Sawada, H Horiuchi, K Inaba, T Sekiguchi, JH Ye, S Miyashita, A Nomura, T Sugawara, K Obara, Y Murakami, K Fujiwara, T Ujihara, G Sazaki, N Usami, M Oku, Y Yokoyama, S Kohiki, Y Kawazoe, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS　42　(12)　7292-7293　2003/12

DOI： 10.1143/JJAP.42.7292 　

ISSN： 0021-4922
Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure Peer-reviewed

A Alguno, N Usami, T Ujihara, K Fujiwara, G Sazaki, K Nakajima, Y Shiraki

APPLIED PHYSICS LETTERS　83　(6)　1258-1260　2003/08

DOI： 10.1063/1.1600838 　

ISSN： 0003-6951
Stacked Ge islands for photovoltaic applications Peer-reviewed

N. Usami, A. Alguno, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, K. Sawano, Y. Shiraki

SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS　4　(4)　367-370　2003/07

DOI： 10.1016/S1468-6996(03)00054-8 　

ISSN： 1468-6996
Influence of the elastic strain on the band structure of ellipsoidal SiGe coherently embedded in the Si matrix Peer-reviewed

N Usami, T Ichitsubo, T Ujihara, T Takahashi, K Fujiwara, G Sazaki, K Nakajima

JOURNAL OF APPLIED PHYSICS　94　(2)　916-920　2003/07

DOI： 10.1063/1.1580194 　

ISSN： 0021-8979
Effects of high pressure on the growth kinetics of orthorhombic lysozyme crystals Peer-reviewed

Y Nagatoshi, G Sazaki, Y Suzuki, S Miyashita, T Matsui, T Ujihara, K Fujiwara, N Usami, K Nakajima

JOURNAL OF CRYSTAL GROWTH　254　(1-2)　188-195　2003/06

DOI： 10.1016/S0022-0248(03)01151-5 　

ISSN： 0022-0248
Growth of SiGe bulk crystals with uniform composition by utilizing feedback control system of the crystal-melt interface position for precise control of the growth temperature Peer-reviewed

Y Azuma, N Usami, T Ujihara, K Fujiwara, G Sazaki, Y Murakami, K Nakajima

JOURNAL OF CRYSTAL GROWTH　250　(3-4)　298-304　2003/04

DOI： 10.1016/S0022-0248(02)02400-4 　

ISSN： 0022-0248
Fabrication of SiGe-on-insulator through thermal diffusion of Ge on Si-on-insulator substrate Peer-reviewed

K Kutsukake, N Usami, K Fujiwara, T Ujihara, G Sazaki, BP Zhang, Y Segawa, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS　42　(3A)　L232-L234　2003/03

DOI： 10.1143/JJAP.42.L232 　

ISSN： 0021-4922
High-quality crystalline silicon layer grown by liquid phase epitaxy method at low growth temperature Peer-reviewed

T Ujihara, K Obara, N Usami, K Fujiwara, G Sazaki, T Shishido, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS　42　(3A)　L217-L219　2003/03

DOI： 10.1143/JJAP.42.L217 　

ISSN： 0021-4922
Direct observations of crystal growth from silicon melt Peer-reviewed

K Fujiwara, K Nakajima, T Ujihara, N Usami, G Sazaki, H Hasegawa, S Mizoguchi, K Nakajima

PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C　110-113　2003
Structure and property of directionally grown SiGe multicrystals with microscopic compositional distribution Peer-reviewed

K Fujiwara, T Takahashi, N Usami, T Ujihara, G Sazaki, K Nakajima

PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C　158-160　2003
What is the most important growth parameter on crystal quality of the silicon layer by LPE method? Peer-reviewed

T Ujihara, K Obara, N Usami, K Fujiwara, G Sazaki, T Shishido, K Nakajima

PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C　1241-1244　2003
Improved quantum efficiency of solar cells with Ge dots stacked in multilayer structure Peer-reviewed

A Alguno, N Usami, T Ujihara, K Fujiwara, K Sawano, G Sazaki, Y Shiraki, K Nakajima

PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C　2746-2749　2003
Strain distribution of Si thin film grown on multicrystalline-SiGe with microscopic compositional distribution Peer-reviewed

N Usami, T Takahashi, K Fujiwara, T Ujihara, G Sazaki, Y Murakami, K Nakajima

JOURNAL OF APPLIED PHYSICS　92　(12)　7098-7101　2002/12

DOI： 10.1063/1.1520724 　

ISSN： 0021-8979
Evaluation of the diffusion coefficients in liquid GaGe binary alloys using a novel method based on Fick's first law Peer-reviewed

Toru Ujihara, Kozo Fujiwara, Gen Sazaki, Noritaka Usami, Kazuo Nakajima

Journal of Non-Crystalline Solids　312-314　196-202　2002/10

DOI： 10.1016/S0022-3093(02)01696-4 　

ISSN： 0022-3093
In situ observations of crystal growth behavior of silicon melt Peer-reviewed

K Fujiwara, K Nakajima, T Ujihara, N Usami, G Sazaki, H Hasegawa, S Mizoguchi, K Nakajima

JOURNAL OF CRYSTAL GROWTH　243　(2)　275-282　2002/08

DOI： 10.1016/S0022-0248(02)01521-X 　

ISSN： 0022-0248
Growth and properties of SiGe multicrystals with microscopic compositional distribution for high-efficiency solar cells Peer-reviewed

K Nakajima, N Usami, K Fujiwara, Y Murakami, T Ujihara, G Sazaki, T Shishido

SOLAR ENERGY MATERIALS AND SOLAR CELLS　73　(3)　305-320　2002/07

DOI： 10.1016/S0927-0248(01)00216-1 　

ISSN： 0927-0248
Evidence of the presence of built-in strain in multicrystalline SiGe with large compositional distribution Peer-reviewed

N Usami, T Takahashi, K Fujiwara, T Ujihara, G Sazaki, Y Murakami, K Nakajima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS　41　(7A)　4462-4465　2002/07

DOI： 10.1143/JJAP.41.4462 　

ISSN： 0021-4922
Simultaneous in situ measurement of solute and temperature distributions in the alloy solutions Peer-reviewed

T Ujihara, K Fujiwara, G Sazaki, N Usami, K Nakajima

JOURNAL OF CRYSTAL GROWTH　242　(3-4)　313-320　2002/07

DOI： 10.1016/S0022-0248(02)01423-9 　

ISSN： 0022-0248
New method for measurement of interdiffusion coefficient in high temperature solutions based on Fick's first law Peer-reviewed

T Ujihara, K Fujiwara, G Sazaki, N Usami, K Nakajima

JOURNAL OF CRYSTAL GROWTH　241　(3)　387-394　2002/06

DOI： 10.1016/S0022-0248(02)01316-7 　

ISSN： 0022-0248
Compositional variation in Si-rich SiGe single crystals grown by multi-component zone melting method using Si seed and source crystals Peer-reviewed

K Nakajima, T Kusunoki, Y Azuma, N Usami, K Fujiwara, T Ujihara, G Sazaki, T Shishido

JOURNAL OF CRYSTAL GROWTH　240　(3-4)　373-381　2002/05

DOI： 10.1016/S0022-0248(02)00940-5 　

ISSN： 0022-0248
Measurement of intrinsic diffusion coefficients of Al and Ni in Ni3Al using Ni/NiAl diffusion couples Peer-reviewed

K Fujiwara, Z Horita

ACTA MATERIALIA　50　(6)　1571-1579　2002/04

DOI： 10.1016/S1359-6454(02)00018-6 　

ISSN： 1359-6454
Melt growth of multicrystalline SiGe with large compositional distribution for new solar cell applications Peer-reviewed

K Nakajima, N Usami, K Fujiwara, Y Murakami, T Ujihara, G Sazaki, T Shishido

SOLAR ENERGY MATERIALS AND SOLAR CELLS　72　(1-4)　93-100　2002/04

DOI： 10.1016/S0927-0248(01)00154-4 　

ISSN： 0927-0248
In-situ monitoring system of the position and temperature at the crystal-solution interface Peer-reviewed

G Sazaki, Y Azuma, S Miyashita, N Usami, T Ujihara, K Fujiwara, Y Murakami, K Nakajima

JOURNAL OF CRYSTAL GROWTH　236　(1-3)　125-131　2002/03

DOI： 10.1016/S0022-0248(01)02171-6 　

ISSN： 0022-0248
Fabrication of SiGe bulk crystals with uniform composition as substrates for Si-based heterostructures Peer-reviewed

N Usami, Y Azuma, T Ujihara, G Sazaki, K Fujiwara, Y Murakami, K Nakajima

MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY　89　(1-3)　364-367　2002/02

DOI： 10.1016/S0921-5107(01)00775-9 　

ISSN： 0921-5107
Control of macroscopic absorption coefficient of multicrystalline SiGe by microscopic compositional distribution Peer-reviewed

Noritaka Usami, Kozo Fujiwara, Toru Ujihara, Gen Sazaki, Hiroyuki Yaguchi, Yoshihiro Murakami, Kazuo Nakajima

Japanese Journal of Applied Physics, Part 2: Letters　41　(1 A/B)　37-39　2002/01/15

DOI： 10.1143/JJAP.41.L37 　

ISSN： 0021-4922
Effect of growth temperature on surface morphology and crystal quality of Si thin-film by liquid phase epitaxial growth technique Peer-reviewed

Toru Ujihara, Eiji Kanda, Kozo Fujiwara, Noritaka Usami, Gen Sazaki, Kazuo Nakajima

408-411　2002
Si/multicrystalline-SiGe heterostructure as a candidate for solar cells with high conversion efficiency Peer-reviewed

N Usami, T Takahashi, K Fujiwara, T Ujihara, G Sazaki, Y Murakami, K Nakajima

CONFERENCE RECORD OF THE TWENTY-NINTH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE 2002　247-249　2002
Grain growth of polycrystalline Si thin film for solar cells and its effect on crystal properties Peer-reviewed

T Ujihara, E Kanda, K Fujiwara, G Sazaki, N Usami, Y Murakami, K Kitahara, K Nakajima

CONFERENCE RECORD OF THE TWENTY-NINTH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE 2002　1339-1342　2002
Crystal growth of silicon-germanium homogeneous bulk crystal and related measurement

UJIHARA Toru, AZUMA Yukinaga, USAMI Noritaka, SAZAKI Gen, FUJIWARA Kozo, SHISHIDO Toetsu, NAKAJIMA Kazuo

J. Japanese association for crystal growth　29　(5)　339-348　2002
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

To prepare a silicon-germanium bulk crystal with uniform composition distribution, it is necessary to supply solute component to the growth interface and to control the growth interface temperature. The multicomponent zone melting method with the feedback system of the growth interface temperature which we established fulfills these necessary conditions. The homogeneous bulk crystal with the length of 20 mm over was successfully grown by this method. This paper provides an overview of this growth method and related in-situ techniques to measure position and temperature of growth interface during the crystal growth. To grow high quality crystals, it is also necessary to control supercooling and supersaturation in the solution. We also introduce an in-situ observation technique for supersaturation.
In situ observation of the Marangoni convection in a NaCl aqueous solutions under microgravity Peer-reviewed

G Sazaki, S Miyashita, M Nokura, T Ujihara, K Fujiwara, N Usami, K Nakajima

JOURNAL OF CRYSTAL GROWTH　234　(2-3)　516-522　2002/01

DOI： 10.1016/S0022-0248(01)01717-1 　

ISSN： 0022-0248
Physical model for the evaluation of solid-liquid interfacial tension in silicon Peer-reviewed

T Ujihara, G Sazaki, K Fujiwara, N Usami, K Nakajima

JOURNAL OF APPLIED PHYSICS　90　(2)　750-755　2001/07

DOI： 10.1063/1.1379349 　

ISSN： 0021-8979
Growth of SiGe bulk crystal with uniform composition by directly controlling the growth temperature at the crystal-melt inter-face using in situ monitoring system Peer-reviewed

Y Azuma, N Usami, T Ujihara, G Sazaki, Y Murakami, S Miyashita, K Fujiwara, K Nakajima

JOURNAL OF CRYSTAL GROWTH　224　(3-4)　204-211　2001/04

DOI： 10.1016/S0022-0248(01)00974-5 　

ISSN： 0022-0248
Intrinsic diffusion in Ni3Al Peer-reviewed

K Fujiwara, Z Horita

DIFFUSIONS IN MATERIALS: DIMAT2000, PTS 1 & 2　194-1　565-570　2001

ISSN： 1012-0386
Growth of Ni₃Al in Ni/NiAl Diffusion Couples Peer-reviewed

FUJIWARA Kozo

The Third Pacific Rim International Conference on Advanced Materials and Processing　1251-1256　1998
Formation of Ni5Al3 phase in Ni3Al/NiAl diffusion couples Peer-reviewed

Y Ootoshi, K Fujiwara, Z Horita, M Nemoto

MATERIALS TRANSACTIONS JIM　39　(1)　225-229　1998/01

DOI： 10.2320/matertrans1989.39.225 　

ISSN： 0916-1821
Interfacial observations of Ni/Ni3Si and Ni/Ni3Ga diffusion couples Peer-reviewed

Z Horita, K Fujiwara, Y Ootoshi, N Komai, M Watanabe, M Nemoto

PHILOSOPHICAL MAGAZINE LETTERS　75　(3)　149-153　1997/03

DOI： 10.1080/095008397179705 　

ISSN： 0950-0839
Orientation Relationship in Ni/Ni₃X(X=Al, Si, Ga, Ge)Diffusion-Couple Interfaces Peer-reviewed

FUJIWARA Kozo

Interface Science and Materials Interconnection Proceedings of JIMIS-8　427-430　1996

Show all ︎Show first 5

Misc. 60

研究室紹介:液相成長ダイナミクスの総合理解と高機能結晶創製への挑戦

藤原航三, 森戸春彦, 前田健作, 志賀敬次

Crystal letters = 結晶工学ニュース / 応用物理学会結晶工学分科会編　(76)　50-55　2021/01
Publisher: [東京] : 応用物理学会結晶工学分科会
ISSN： 2423-8791
Configuration of point defects of impurity-doped congruent lithium niobate

Chihiro Koyama, Jun Nozawa, Kozo Fujiwara, Satoshi Uda

Journal of the Japanese Association for Crystal Growth　43　(3)　131-138　2016/10/31
Publisher: The Japanese Association for Crystal Growth
DOI： 10.19009/jjacg.43.3_131 　

ISSN： 2188-7268

More details Close

 The defect structures of impurity-doped congruent lithium niobates (c-LN) were investigated by combining lattice constant measurements with thermodynamic analyses. On the basis of the "Li site vacancy model", six kinds of defect structures in impurity-doped c-LN are possible. Using thermodynamic constraints, these can be narrowed down to two kinds. The thermodynamic analyses showed impurities are located at only the Li or Nb site in the range where antisite niobium exists. Based on the thermodynamic analyses, lattice constant measurement revealed that divalent and trivalent impurities were located at Li sites in LN, whereas tetravalent impurities were located at Nb sites. This result provides good clues for controlling intrinsic point defects.
Impurity Partitioning during Colloidal Crystallization

Jun Nozawa, Sumeng Hu, Haruhiko Koizumi, Kozo Fujiwara, Satoshi Uda

Journal of the Japanese Association for Crystal Growth　43　(2)　88-96　2016/07/29
Publisher: The Japanese Association for Crystal Growth
DOI： 10.19009/jjacg.43.2_88 　

ISSN： 2188-7268

More details Close

 To obtain high quality colloidal crystals, control of impurity behavior during crystallization is required. We have investigated impurity partitioning quantitatively for the colloidal crystal. We applied conventional partition model of normal crystal growth such as Thurmond and Struthers model and Burton Prim Slichter (BPS) model to colloidal crystal growth, which provides equilibrium partition coefficient (k₀). Discussion on the basis of free energy derived from volume fraction of colloidal particles well account for variation of k₀s for impurity of different size. In-situ observation revealed detailed partition behavior, including orientation-dependency, the effect of the grain boundary, and the morphology of solid-liquid interface. These new findings contribute to constructing methodology for growing high quality colloidal crystal as well as understanding general concept of partitioning that takes place during phase transition.
The 45th National Conference on Crystal Growth (NCCG-45)(News of JACG)

Journal of the Japanese Association of Crystal Growth　42　(4)　299-304　2016/01
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 2187-8366
The 45th National Conference on Crystal Growth (NCCG-45)(News of JACG)

佐藤元, 藤原航三, 樋口幹雄, 太子敏則, 片山竜二, 山中淳平, 鈴木良尚, 小泉晴比古, 三浦均, 野澤純, 新家寛正, 島村清史, 勝野弘康, 本間宏成, 藤原貴久, 谷口尚, 三宅秀人, 寒川義裕, 長嶋剣, 丸山美帆子, 吉川彰, 手嶋勝弥

Journal of the Japanese Association for Crystal Growth　42　(4)　299-304　2016
Publisher: 日本結晶成長学会
ISSN： 0385-6275
88th Bulk Crystal Growth Seminar : Silicon Crystal for Solar Cells "-from Crystal Growth to Processing-"(News of JACG)

Fujiwara Kozo

Journal of the Japanese Association of Crystal Growth　40　(3)　203-203　2013/10
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275
Control of nucleation process for proteins under application of an external alternating current electric field

Haruhiko Koizumi, Satoshi Uda, Kozo Fujiwara, Jun Nozawa

Journal of the Japanese Association for Crystal Growth　40　(2)　98-106　2013/07
Publisher: Japanese Association for Crystal Growth
DOI： 10.19009/jjacg.40.2_98 　
Improvement of photovoltaic characteristics of B-doped Czochralski-Silicon by Ge codoping (シリコン材料・デバイス)

ARIVANANDHAN Mukannan, GOTOH Raira, FUJIWARA Kozo

電子情報通信学会技術研究報告 = IEICE technical report : 信学技報　113　(41)　105-109　2013/05/16
Publisher: 電子情報通信学会
ISSN： 0913-5685
Growth Mechanism of Si Faceted Dendrites

FUJIWARA Kozo

Journal of the Japanese Association of Crystal Growth　39　(3)　122-127　2012/10/31
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

Si-faceted dendrites have unique crystal structures. The surface of dendrites is bounded by {111} facet planes, at least two parallel {111} twin boundaries exist at the center of the dendrites, and the preferential growth directions are <112> or <110>. Moreover, the growth velocity of dendrites is larger than equiaxed crystal grains. Such features can be applied in technology for growing multicrystalline Si (mc-Si) ingots for solar cells. We succeeded in observing the growth processes of Si <112> and <110> faceted dendrites by using originally developed in situ observation system. The growth scheme for the growth shape of the <112> and <110> dendrites were established based on our experimental evidence. The theoretical <112> and <110> dendrite growth velocities were calculated on the basis of the growth model established by our studies.
Development of Crystal Growth Technology towards High-Quality Silicon Crystal for Solar Cells

FUJIWARA Kozo, UDA Satoshi

Journal of the Japanese Association of Crystal Growth　39　(3)　109-109　2012/10/31
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275
Fabrication of quasi-phase-matching structure by periodic twin in paraerectric borate crystal

Kensaku Maeda, Satoshi Uda, Kozo Fujiwara

（独）日本学術振興会弾性波素子技術第150委員会第126回研究会資料　33-38　2012/07/25
Publisher: 独立行政法人日本学術振興会

More details Close

招待講演
Enhancement of Crystal Perfection for Tetragonal Hen-egg White Lysozyme Crystals under Application of an External AC Electric Field

Haruhiko Koizumi, Satoshi Uda, Kozo Fujiwara, Masaru Tachibana, Kenichi Kojima, Jun Nozawa

Photon Factory Activity Report 2011 Part B: Users' Report　29　198-1-198-2　2012
Publisher: High Energy Accelerator Research Organization (KEK)
Arrangement of dendrite crystals grown along the bottom of Si ingots using the dendritic casting method by controlling thermal conductivity under crucibles

Kazuo Nakajima, Kentaro Kutsukake, Kozo Fujiwara, Kohei Morishita, Satoshi Ono

JOURNAL OF CRYSTAL GROWTH　319　(1)　13-18　2011/03

DOI： 10.1016/j.jcrysgro.2011.01.069 　

ISSN： 0022-0248

eISSN： 1873-5002
Generation mechanism of dislocations in multicrystalline Si during 2D growth

Kentaro Kutsukake, Takuro Abe, Noritaka Usami, Kozo Fujiwara, Ichiro Yonenaga, Kohei Morishita, Kazuo Nakajima

Proceedings of 26th European Photovoltaic Solar Energy Conference and Exhibition　1934-1937　2011
FORMATION MECHANISM OF TWIN BOUNDARIES IN SILICON MULTICRYSTALS DURING CRYSTAL GROWTH

K. Kutsukake, T. Abe, N. Usami, K. Fujiwara, K. Morishita, K. Nakajima

35TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE　810-811　2010

DOI： 10.1109/PVSC.2010.5617200 　

ISSN： 0160-8371
HIGH EFFICIENCY SOLAR CELLS OBTAINED FROM SMALL SIZE INGOTS WITH 30 CM Phi BY CONTROLLING THE DISTRIBUTION AND ORIENTATION OF DENDRITE CRYSTALS GROWN ALONG THE BOTTOM OF THE INGOTS

K. Nakajima, K. Kutsukake, K. Fujiwara, N. Usami, S. Ono, Yamasaki

35TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE　817-819　2010

DOI： 10.1109/PVSC.2010.5617194 　

ISSN： 0160-8371
Enhancement of Ga doping in Czochralski-grown Si crystal by B- or Ge- codoping

S. Uda, X. Huang, M. Arivanandhan, R. Gotoh, K. Fujiwara

Proceedings of the 3rd International Workshop on Crystalline Silicon Solar Cells, Trondheim, Norway, 3-5 June, 2009　2009/06

More details Close

国際会議proceedings CD（単行本等ではない） 査読なし
Change of phase equilibria by an application of an external electric field

S. Uda, H. Koizumi, K. Fujiwara

Proceedings of EUROTHERM Seminar Nr.84, Thermodynamics of phase changes, Namur, Belgium, 24-27 May, 2009　2009/05

More details Close

国際会議proceedings CD（単行本等ではない） 査読なし
Generation mechanisms of sub-grain boundaries in Si bulk multicrystals during crystal growth

USAMI Noritaka, KUTSUKAKE Kentaro, FUJIWARA Kozo, NAKAJIMA Kazuo

IEICE technical report　109　(16)　31-34　2009/04/16
Publisher: The Institute of Electronics, Information and Communication Engineers
ISSN： 0913-5685

More details Close

In order to improve the conversion efficiency of solar cells based on Si multicrystals, it is of great importance to develop novel crystal growth technology to permit manipulation of microstructures in Si multicrystals based on knowledge obtained through fundamental research on crystal growth, generation mechanisms of crystal defects, impact of microstructures and defects on electrical and optical properties. In this paper, we explain generation mechanisms of sub-grain boundaries in Si multicrystals during directional solidification.
太陽電池用高品質シリコンバルク多結晶の製造技術

Noritaka Usami, Kozo Fujiwara, Kentaro Kutsukake, Kazuo Nakajima

電子材料,株式会社工業調査会　48　(2)　10-16　2009
Fundamental Study of Sub-Grain Boundaries in Si

Kentaro Kutsukake, Noritaka Usami, Kozo Fujiwara, Kazuo Nakajima

Journal of the Japanese Association for Crystal Growth,Japanese Association for Crystal Growth　36　(4)　253-260　2009

DOI： 10.19009/jjacg.36.4_253 　
Control of microstructures and crystal defects in Si multicrystals grown by the casting method - how to improve the quality of multicrystals to the level of single crystals –

Kazuo Nakajima, Noritaka Usami, Kozo Fujiwara, Kentaro Kutsukake

24th European Photovoltaic Solar Energy Conference and Exhibition (EUPVSEC)　21-24　2009
Development of high-quality Si multicrystals and application for solar cells

Optronics　27　(9)　138-143　2008/09
Publisher: オプトロニクス社
ISSN： 0286-9659
Control of microstructures of Si bulk multicrystals for improvement of solar cell performance

USAMI Noritaka, FUJIWARA Kozo, KUTSUKAKE Kentaro, NAKAJIMA Kazuo

IEICE technical report　108　(2)　73-76　2008/04/04
Publisher: The Institute of Electronics, Information and Communication Engineers
ISSN： 0913-5685

More details Close

We have proposed that artificial control of microstructures in Si multicrystals is promising for improvement of conversion efficiency of practical solar cells. Toward this goal, we attempt to develop novel crystal growth technology to permit manipulation of microstructures in Si multicrystals based on knowledge obtained through fundamental research on crystal growth. In this paper, we overview our recent research activities including model crystal growth and in situ observation for clarifying growth mechanisms, and "dendritic casting method" to realize high-quality Si multicrystals.
One-dimensionally curved Si and Ge single crystal wafers prepared by hot-pressing: Potential performance for optical components for X-ray diffraction Peer-reviewed

Hiroshi Okuda, Shojiro Ochiai, Kozo Fujiwara, Kazuo Nakajima

Journal of Physics: Conference Series　83　(1)　2007/06/01
Publisher: Institute of Physics Publishing
DOI： 10.1088/1742-6596/83/1/012030 　

ISSN： 1742-6596 1742-6588
20aXB-2 Plastic deformation of silicon wafer to shaped-crystal

Yonenaga I., Fujiwara K., Okuda Koji, Nakajima K.

Meeting abstracts of the Physical Society of Japan　62　(1)　966-966　2007/02/28
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Spontaneous modification of grain boundary configuration and its application for realization of bulk multicrystalline SI with electrically inactive grain boundaries Peer-reviewed

Noritaka Usami, Kentaro Kutsukake, Takamasa Sugawara, Kozo Fujiwara, Wugen Pan, Yoshitaro Nose, Toetsu Shishido, Kazuo Nakajima

Conference Record of the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion, WCPEC-4　1　960-963　2007

DOI： 10.1109/WCPEC.2006.279616 　
シリコンバルク多結晶太陽電池の粒界設計に向けて

沓掛健太朗, 宇佐美徳隆, 藤原航三, 中嶋一雄

マテリアルインテグレーションティー・アイ・シー　20　(10)　31-36　2007
太陽電池用Siバルク多結晶成長技術

Usami Noritaka, Fujiwara Kozo, Pan Gokon, Kutsukake Kentaro, Nose Yoshitaro, Nakajima Kazuo

工業材料,日刊工業新聞社　55　(2)　69-72　2007
Publisher: 日刊工業新聞社
ISSN： 0452-2834
A new technique for quantitative analysis of sub-grain boundary density and its influence on minority carrier diffusion length in bulk multicrystalline silicon

K. Kutsukake, N. Usami, T. Ohtaniuchi, K. Fujiwara, Y. Nose, K. Nakajima

22nd European Photovoltaic Solar Energy Conference　1371-1373　2007
Structural modification in multicrystalline Si during directional solidification revealed by spatially resolved X-ray rocking curve analysis

N. Usami, K. Kutsukake, K. Fujiwara, K. Nakajima

22nd European Photovoltaic Solar Energy Conference　1104-1105　2007
Grain boundary engineering of bulk multicrystallne silicon for solar cell applications

Kutsukake Kentaro, Usami Noritaka, Fujiwara Kozo, Nakajima Kazuo

MATERIALS INTEGRATION,TIC　20　(10)　31-36　2007
Growth of crystalline si film by using liquid phase epitaxy from si pure melt for solar cell applications

K. Kutsukake, H. Kodama, Z. Wang, N. Usami, K. Fujiwara, Y. Nose, K. Nakajima

Technical digest of 17th International Photovoltaic Science and Engineering Conference　585-586　2007
多結晶シリコン太陽電池の高効率化にむけた材料科学的アプローチ ― シリコンバルク多結晶の粒界制御に向けて

宇佐美徳隆, 沓掛健太朗, 藤原航三, 野瀬嘉太郎, 中嶋一雄

まてりあ　45　(10)　720-724　2006/10
Publisher: The Japan Institute of Metals and Materials
DOI： 10.2320/materia.45.720 　

ISSN： 1340-2625
Development of textured high-quality Si multicrystal ingots with same grain orientation and large grain sizes by the new dendritic casting method Peer-reviewed

Kazuo Nakajima, Kozo Fujiwara, Wugen Pan, Masatoshi Tokairin, Yoshitaro Nose, Noritaka Usami

CONFERENCE RECORD OF THE 2006 IEEE 4TH WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS 1 AND 2　1　964-967　2006

DOI： 10.1109/WCPEC.2006.279617 　
Electrical activities of S5 grain boundaries in bulk multiclystalline Si grown by Bridgman method with configurationally controlled seed crystals

K. Kutsukake, N. Usami, K. Fujiwara, W. Pan, Y. Nose, K. Nakajima

21st European Photovoltaic Solar Energy Conference　1029-1031　2006
Toward control of grain boundaries in multicrystalline Si ingot

Usami Noritaka, Kutsukake Kentaro, Fujiwara Kozo, Nose Yoshitaro, Nakajima Kazuo

Materia Japan,The Japan Institute of Metals　45　(10)　720-724　2006
Si系太陽電池用バルク多結晶とその成長技術

藤原航三, 藩伍根, 宇佐美徳隆, 野瀬嘉太郎, 中嶋一雄

ケミカル・エンジニヤリング　51　(51)　45(781)-49(785)　2006
Publisher: 化学工業社
ISSN： 0387-1037
太陽電池用Si系バルク多結晶の結晶成長および太陽電池特性

K. Fujiwara, N. Usami, W. Pan, T. Ujihara, A. Nomura, Y. Nose, T. Shishido, K. Nakajima

Journal of the Japanese Association for Crystal Growth　32　(4)　291-296　2005/09/30
Publisher: 日本結晶成長学会
DOI： 10.19009/jjacg.32.4_291 　

ISSN： 0385-6275

More details Close

Polycrystalline bulk Si materials are the most important materials for solar cells now and in future. High quality polycrystalline materials controlled crystallographic orientation and grain boundary character is demanded for realizing highly energy conversion efficiency of solar cells. In this paper, we introduce the experimental results of in-situ observation of crystal growth behavior from silicon melt. Structural and solar cell properties of polycrystalline SiGe with microscopic compositional distribution are also introduced.
Liquid phase epitaxial growth of Si layers on Si thin substrates from Si pure melts under near-equilibrium conditions

K. Nakajima, K. Fujiwara, Y. Nose, N. Usami

Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers　44　(7A)　5092-5095　2005/07
Investigation of crystal growth behavior of silicon melt for growing high quality polycrystalline silicon by cast method Peer-reviewed

K Fujiwara, N Usami, Y Nose, G Sazaki, K Nakajima

Conference Record of the Thirty-First IEEE Photovoltaic Specialists Conference - 2005　1081-1083　2005

ISSN： 0160-8371
Impurity effects of fluorescent labeled lysozyme on the crystallization of tetragonal and monoclinic crystals

MATSUI T, SAZAKI G, OKADA M, MATSUURA Y, FUJIWARA K, UJIHARA T, USAMI N, NAKAJIMA K

Journal of the Japanese Association of Crystal Growth　31　(3)　194-194　2004/08/25
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

To grow high quality protein crystals, impurity effects have to be studied from the viewpoint of intermolecular bondings. Recently, intermolecular bondings in hen egg-white lysozyme (HEWL) crystals were systematically studied by Matuura and Chemov. Based on their results, we modified the specific surface of HEWL with fluorescent reagent, and studied the impurity effects on the nucleation and growth of tetragonal and monoclinic HEWL crystals.
A comparative study of strain field in strained-Si on SiGe-on-insulator and SiGe virtual substrate

K. Kutsukake, N. Usami, T. Ujihara, K. Fujiwara, K. Nakajima

The first International SiGe: Materials, Processing, and Devices Symposium in the Fall 2004 Electrochemical Society Conference　1179-1187　2004
Hetero-epitaxial structure of organic semiconductor PTCDA thin film crystals on hydrogen-terminated Si (111) surfaces

SAZAKI Gen, FUJINO Takuho, SADOWSKI Jerzy T., USAMI Noritaka, UJIHARA Toru, FUJIWARA Kozo, SAKURAI Toshio, NAKAJIMA Kazuo

Journal of the Japanese Association of Crystal Growth　30　(3)　111-111　2003/07/05
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

Thin film crystals of organic semiconductor PTCDA were grown on hydrogen-terminated Si(111) surfaces by MBE method. Hetero-epitaxial structure of the thin film crystals was determined using UHV-STM. We found that its lattice matching mode is close to commensurate one.
Control of the grain orientation of organic semiconductor PTCDA thin film crystals using vicinal steps on hydrogen-terminated Si (111) surface

SAZAKI Gen, FUJINO Takuho, GUNJI Atsushi, NISHIKATA Susummu, USAMI Noritaka, UJIHARA Toru, FUJIWARA Kozo, NAKAJIMA Kazuo

Journal of the Japanese Association of Crystal Growth　30　(3)　112-112　2003/07/05
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

Orientation of the grains of organic semiconductor PTCDA thin film crystals was controlled using vicinal steps on hydrogen-terminated Si(111) substrates. The ratio of single crystalline grains on the vicinal substrate was 10% larger than that on fiat substrate. This increase in the ratio of single crystalline grains is probably due to the preferential orientation of the PTCDA molecules along the steps.
Real-time measurement of protein concentration for supersaturation control

MATSUI Takuro, SAZAKI Gen, USAMI Noritaka, UJIHARA Toru, FUJIWARA Kozo, NAKAJIMA Kazuo

Journal of the Japanese Association of Crystal Growth　30　(3)　80-80　2003/07/05
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

In protein crystallization, supersaturation control is one of the most basic approaches to grow a high quality single crystal. In order to apply this approach, protein concentration should be monitored all though the crystallization process. Then we tried to develop a real-time monitoring system of protein concentration using a two-beam interferometer. This system enable us to measure the protein concentration with following advantages: wide dynamic range, small volume, and applicable in micro batch and dialysis systems.
Poly-crystallization due to strain-induced constitutional supercooling

UJIHARA Toru, AZUMA Yukinaga, FUJIWARA Kozo, SAZAKI Gen, USAMI Noritaka, NAKAJIMA Kazuo

Journal of the Japanese Association of Crystal Growth　30　(3)　55-55　2003/07/05
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

When a crystal is strained during growth from a solution, the solution in the vicinity of interface is supersaturated. Based on the fact, we proposed the model of poly-crystallization due to strain during solution growth. According to our model, strain free crystals nucleate heterogenerously on the strained crystal and consequently poly-crystallization occurs. The results of Monte Carlo simulations support the model of the poly-crystallization due to strain.
Impact of the annealing temperature on the homogeneity of SiGe-on-insulator

N. Usami, K. Kutsukake, K. Fujiwara, T. Ujihara, G. Sazaki, S. Ito, B. P. Zhang, K. Nakajima

Third International Conference of SiGe(C) Epitaxy and Heterostructures　200-202　2003
Spatial distribution of composion and strain in multicrystalline SiGe bulk crystal and their impact on solar cell applications Peer-reviewed

N Usami, T Takahashi, AC Alguno, K Fujiwara, T Ujihara, T Ichitsubo, G Sazaki, K Nakajima

PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C　A　98-101　2003
Impurity effect on the quality of protein crystals

MATSUI Takuro, SAZAKI Gen, SATO Takao, UJIHARA Toru, FUJIWARA Kozo, USAMI Noritaka, NAKAJIMA Kazuo

Journal of the Japanese Association of Crystal Growth　29　(2)　71-71　2002/07/01
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

Impurity effect was investigated on the crystallization of the hen egg lysozyme tetragonal crystals. From the X-rey diffraction data and the observation of the growth sector boundary, we found that quality of the crystals decreases with a decrease in the supersaturation.
Can strain induce poly-crystallization during melt growth?

UJIHARA Torn, FUJIWARA Kozo., SAZAKI Gen., USAMI Noritaka, NAKAJIMA Kazuo

Journal of the Japanese Association of Crystal Growth　29　(2)　146-146　2002/07/01
Publisher: The Japanese Association for Crystal Growth (JACG)
ISSN： 0385-6275

More details Close

Strain in crystals lowers the melting point. On a basis of this fact, we newly explained the strain induced poly-crystallization during met growth. According to our model, strain free crystal nucleates heterogenerously on the strained crystal from the supercooled melt in the vicinity of liquid-solid interface. Moreover, we successfully reproduced the poly-crystallization due to this model by the Monte Carlo simulation.
Evaluation of the diffusion coefficients in liquid GaGe binary alloys using a novel method based on Fick's first law

T Ujihara, K Fujiwara, G Sazaki, N Usami, K Nakajima

JOURNAL OF NON-CRYSTALLINE SOLIDS　312-14　196-202　2002

ISSN： 0022-3093
In-situ observation of the Marangoni convection in a protein solution under microgravity

SAZAKI Gen, MIYASHITA Satoru, UJIHARA Toru, FUJIWARA Kozo, USAMI Noritaka, NAKAJIMA Kazuo

18　79-79　2001/10/01

ISSN： 0915-3616
Novel measurement method for diffusion coefficients of high temperature solutions based on Fick's first law

FUJIWARA Kozo, UJIHARA Toru, SAZAKI Gen, USAMI Noritaka, NAKAJIMA Kazuo

18　65-65　2001/10/01

ISSN： 0915-3616
Evaluation of the quality of protein crystals by X-ray Laue topography

Sazaki G., Matsui T., Miyashita S., Hondoh H., Yanagiya S., Kajiwara K., Imai Y., Izumi K., Ujihara T., Fujiwara K., Usami N., Nakajima K.

Meeting abstracts of the Physical Society of Japan　56　(2)　719-719　2001/09/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Structural analysis of diffusion-couple interface using EBSP

Kozo Fujiwara, Zenji Horita

Materia Japan　40　(7)　634-637　2001/07/20
Publisher: 日本金属学会
DOI： 10.2320/materia.40.634 　

ISSN： 1340-2625
Effects of protein concentration and gas adsorption on the Marangoni convection of protein solution

Sazaki G., Miyashita S., Ujihara T., Fujiwara K., Usami N., Nakajima K.

Meeting abstracts of the Physical Society of Japan　56　(1)　781-781　2001/03/09
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Measurements of interdiffusion coefficients and intrinsic diffusion coefficients in Ni₃Al

Kozo Fujiwara, Zenji Horita

Materia Japan　39　(6)　507-510　2000/06/20
Publisher: 日本金属学会
DOI： 10.2320/materia.39.507 　

ISSN： 1340-2625
Crystallographi Orientation Alnlysis at the Diffusion Couple Interface by OIM

FUJIWARA K., HORITA Z.

35　242-242　2000/05/01

ISSN： 0417-0326
Measurements of intrinsic diffusion coefficients in Ni3Al

K Fujiwara, M Watanabe, Z Horita, M Nemoto, K Noumi, T Simozaki

JAPAN INSTITUTE OF METALS, PROCEEDINGS, VOL 12, (JIMIC-3), PTS 1 AND 2　481-484　1999

Show all ︎Show first 5

Books and Other Publications 3

Handbook of Crystal Growth, Second Edition, Vol. I

Kozo Fujiwara

2014
太陽電池の基礎と応用

藤原航三, 宇佐美徳隆, 中嶋一雄

培風館　2010/07
Crystal Growth of Si for Solar Cells

K. Fujiwara, K. Nakajima

Springer　2009

Presentations 26

Dynamics at solid-liquid Interface of Si Invited

Kozo FUJIWARA

The 12th International Workshop on Crystalline Silicon for Solar Cells　2024/05/29
Instability of crystal/melt interface of Si and Si1-xGex Invited

Kozo Fujiwara

3rd International Symporium on "Modeling of Crystal Growth Processes and Devices" (MCGPD-2023)　2023/03/06
In-situ observation of crystal/melt interface morphology during directional solidification of semicondustor materials Invited

Kozo Fujiwara

5th International Workshop on Advanced Functional Nanomaterials (IWAN-5, 2023)　2023/03/03
In-situ observations of crystal growth behaviors of silicon during solidification Invited

Kozo Fujiwara

2022 international conferences on the science and technology of devices and materials（SSDM2022）　2022/09/27
Morphology of Crystals in Melt Growth Processes Invited

Kozo Fujiwara

The 4th Symposium for The Core Research Cluster for Materials Science andthe 3rd Symposium on International Joint Graduate Program in Materials Science　2020/11/18
Siの固液界面現象に及ぼす結晶粒界の影響 Invited

藤原航三

応用物理学会秋季学術講演会　2020/09/08
In situ observation of melt growth behaviors of silicon Invited

Kozo Fujiwara

MRS Fall meeting　2019/12/04
CZ-Si単結晶より高品質なSi多結晶の実現を目指して

藤原航三

第３回『各種SiC結晶成長法における高品質化とその応用』　2015/12/11
In situ observations of crystal/melt interface during unidirectional growth of silicon International-presentation

K. Fujiwara

11th International Conference on Ceramic Materials and Components for Energy and Environmental Applications　2015/06/14
Si多結晶の一方向成長過程における固液界面形状に及ぼす結晶粒界の影響

藤原航三, 石井雅也, 前田健作, 小泉晴比古, 野澤純, 宇田聡

第43回結晶成長国内会議　2013/11
Analysis of silicon solidification by in-situ techniques International-presentation

Kozo Fujiwara

Workshop: Polycrystalline growth of Si - new insights from experiment and modeling　2013/09
Cryatal/melt interface morphology at grain boundaries of multicrystalline silicon International-presentation

Kozo Fujiwara, Masaya Ishii, kensaku Maeda, Haruhiko Koizumi, Jun Nozawa, Satoshi Uda

17th International Conference on Crystal Growth and Epitaxy (ICCGE-17)　2013/08
シリコンの一方向凝固過程における不純物偏析

藤原航三

日本結晶成長学会バルク成長分科会第88回研究会　2013/06
Crystal growth mechanisms of silicon during melt growth processes International-presentation

Kozo Fujiwara, Haruhiko Koizumi, Jun Nozawa, Satoshi Uda

2012 International Conference on Solid State Devices and Materials (SSDM 2012)　2012/09/25
太陽電池用Si系材料の融液成長メカニズムと結晶成長技術

藤原航三, 後藤頼良, 前田健作, 小泉晴比古, 野澤純, 宇田聡

電気化学会第79回大会　2012/03/29
Siファセットデンドライトの成長メカニズム

藤原航三

第41回結晶成長国内会議　2011/11
Siの一方向成長過程における成長界面の形状変化

藤原航三, 後藤頼良, Xinbo Yang, 小泉晴比古, 野澤純, 宇田聡

第41回結晶成長国内会議　2011/11
Si<110>デンドライトの成長メカニズム

藤原航三, Xinbo Yang, 小泉晴比古, 野澤純, 宇田聡

日本金属学会　2011/11
Siの結晶成長界面の形状変化

日本金属学会秋期(第147回)大会　2010/09
Growth mechanism of Si faceted dendrites and its application to the casting method for growing structure-controlled polycrystalline Si ingots International-presentation

The 16th International Conference on Crystal Growth　2010/08
Si融液からの結晶成長メカニズム

第27回無機・分析化学コロキウム　2010/05
Siの結晶成長メカニズムと太陽電池用高品質Siバルク多結晶インゴットの成長技術

第44回応用物理学会スクール　2009/03
Siのファセットデンドライトの成長メカニズム

日本学術振興会結晶成長の科学と技術第161委員会第59回研究会　2008/12/19
大粒径多結晶シリコンの育成

藤原航三, 宇佐美徳隆, 沓掛健太朗, 中嶋一雄

日本学術振興会「結晶加工と評価技術」第145委員会第113回研究会　2008/01
Siの融液成長過程の直接観察

第2回フラックス成長研究発表会　2007/12

More details Close

藤原航三、宇佐美徳隆、野村明子、宍戸統悦、中嶋一雄
太陽電池用高品質Siバルク多結晶インゴットの成長技術の開発

藤原航三, 宇佐美徳隆, 東海林雅俊, 前田健作, 野村明子, 宍戸統悦, 中嶋一雄

日本セラミックス協会第20回秋季シンポジウム　2007/09

Show all Show first 5

Industrial Property Rights 10

Si結晶およびその製造方法

宇田聡, Mukannan Arivanandhan, 後藤頼良, 藤原航三

Property Type: Patent
バルク多結晶材料の製造方法

宇佐美徳隆, 藤原航三, 中嶋一雄

Property Type: Patent
半導体結晶体の加工方法、光・電子デバイス用ウェハー結晶体、及び太陽電池システム

中嶋一雄, 藤原航三

Property Type: Patent
大口径CZ単結晶および成長装置とその成長方法

藤原航三, 堀岡佑吉, 勝亦具慶

Property Type: Patent
半導体バルク多結晶の作製方法

藤原航三, 中嶋一雄

特許第4203603号

Property Type: Patent
結晶成長方法、バルク単結晶成長用バルク予備結晶、及びバルク単結晶成長用バルク予備結晶の作製方法

中嶋一雄, 我妻幸長, 宇佐美徳隆, 藤原航三, 宇治原徹

特許第4122382号

Property Type: Patent
光起電力素子、太陽電池、及び光起電力素子の製造方法

宇佐美徳隆, 中嶋一雄, 宇治原徹, 藤原航三

特許第3893466号

Property Type: Patent
Ｇｅ系結晶の製造方法

中嶋一雄, 藤原航三, 宇佐美徳隆, 宇治原徹, 我妻幸長

特許第3855059号

Property Type: Patent
Ｓｉ系結晶の製造方法

中嶋一雄, 藤原航三, 宇佐美徳隆, 宇治原徹, 我妻幸長

特許第4054873号

Property Type: Patent
Ｓｉ薄膜の作製方法

中嶋一雄, 宇佐美徳隆, 宇治原徹, 藤原航三

特許第3978494号

Property Type: Patent

Show all Show first 5

Research Projects 21

フォトン・カウンティング機能による顎骨の多元分析を可能とした歯科用ＣＴの開発

飯久保正弘, 青木徹, 山内健介, 河合泰輔, 石幡浩志, 五十嵐千浪, 藤原航三, 小嶋郁穂

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2024/04/01 - 2028/03/31
その場観察法による各種半導体材料の固液界面不安定化現象の解明と高温物性値の決定

藤原航三, 前田健作

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(A)

Institution: 東北大学

2021/04/05 - 2025/03/31

More details Close

本研究では、単成分半導体、混晶半導体、化合物半導体の固液界面不安定化現象を明らかにし、固液界面物性を測定することを目的としている。本年度は、その場観察装置を用いて、Si，SixGe1-x，Sb，InSbの固液界面現象の観察実験を行った。混晶半導体SixGe1-xにおいては，広い組成範囲でデンドライト成長の形状を観察することに成功し，いずれの組成においてもSiと同タイプのファセットデンドライトが成長することを確認した。また，一方向凝固過程において，結晶中に平行双晶が存在していると，平坦な固液界面が不安定化する前にデンドライト成長が開始することを明らかにした。純Sbでは，平坦な固液界面が不安定化するとファセット面で囲まれたジグザグ状の固液界面が形成されることを示した。従来の報告では、純Sbがファセット性の物質かノンファセットの物質化がはっきりしていなかったが，本研究によりファセット性の物質であることが明らかになった。また、Sbの｛1-112}面がファセット面であることを明らかにした。化合物半導体InSb多結晶の固液界面観察も行った。固液界面における粒界位置での不安定化によりファセット面で囲まれた粒界グルーブが形成され、グルーブ内の融液が急速成長することによって双晶界面が形成される様子を直接観察することに成功した。Si多結晶の固液界面観察では、固液界面において2つの結晶粒界の衝突により新たな結晶粒界が形成される様子を観察することに成功した。また、本研究で対象としている材料の一つであるCdTeの結晶成長実験用の新規結晶成長炉を導入した。
フォトン・カウンティング機能を搭載した新しい組織分析型歯科用ＣＴの開発

飯久保正弘, 青木徹, 佐々木啓一, 河合泰輔, 石幡浩志, 小林馨, 荒木和之, 藤原航三, 小嶋郁穂

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2020/04/01 - 2024/03/31

More details Close

歯科用コーンビームCT（歯科用CT）は、Ｘ線不透過性の極めて高いインプラントや歯科材料が撮影範囲に含まれるため、アーチファクトの軽減と組織のＸ線吸収値の安定化（定量化）が課題である。近年、微弱なＸ線を感知する素子としてテルル化カドミウム（CdTe）半導体が注目されている。CdTe半導体は、Ｘ線を直接感知することができるため検出感度や画質の低下が少なく、光子（フォトン）をそのままカウントすることにより、物質の原子番号や電子密度によるエネルギースペクトルの変化を定量評価することが可能である。本研究は、CdTe半導体検出器を歯科用CTに搭載することで、歯科用CTに実用可能なフォトン・カウンティング機能を開発し、骨や歯のエックス線に対するモノクロマティック特性に依存した多元的分析が可能であり、かつアーチファクトの極めて少ない、高い濃度分解能、空間分解能を有した歯科用CT装置の実現化を目指すものである。 2021年度は１）高電圧出力を可能とした管球およびライン型CdTe半導体検出器をプロトタイプの歯科用CT開発用冶具（以下、開発用冶具）に設置した。２）抜去歯に対し、CdTe半導体検出器によるフォトン・カウンティング機能を用いて、エナメル質と象牙質の実効原子番号及び電子密度の算出を可能とする計算式を検討し、そのカラー画像化を試みた。その結果、エナメル質と象牙質には明瞭な差が確認され、う蝕についても明瞭にカラ―表示が可能であった。３）フォトンカウンティングを用いて、下限値設定を行っての画像化を検討した。
Study on crystal growth dynamics at crystal/melt interface by in situ observation technique

FUJIWARA Kozo

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2017/04/01 - 2020/03/31

More details Close

In this research, we aim to elucidate various phenomena that occur at the crystal-melt interface in the melt growth processes by in situ observation technique. In order to clarify experimentally the effect of the temperature field on the crystal growth dynamics, we constructed a new experimental apparatus that enables non-contact temperature measurement. By using this experimental apparatus, crystal-melt interfaces of many substances such as single element semiconductor (Si), semimetal (Sb), metal (Cu), semiconductor alloy (SiGe), and compound semiconductor (GaSb), were successfully observed directly, and various phenomena occurring at the crystal-melt interfaces were clarified.
Study on melt growth mechanisms of multicrystalline silicon by in situ observations(Fostering Joint International Research)

Fujiwara Kozo, Miller Wolfram

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)

Institution: Tohoku University

2016 - 2018

More details Close

The objective of this collaborative study is to fundamentaly clarify the melt growth mechanisms of multicrystalline silicon (mc-Si) which is widely used for solar cells. There are variety types of crystal defects, which degrade the solar cell performance, in mc-Si wafers. In this study, we directly observed the crystal growth behaviors of mc-Si at around 1400℃ to clarify how crystalline defects are formed at a crystal/melt interface during crystal growth from the melt by using an in situ observation system. Further, those mechanisms were theoretically clarified in the Institute for Crystal Growht (IKZ) in Germany. Based on the fundamental research results of crystal growth, we developed the growth technology of mc-Si ingot.
Study of melt growth mechanisms of multicrystalline Si by in situ observations

Fujiwara Kozo

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2014/06/27 - 2017/03/31

More details Close

The fundamental melt growth mechanisms of multicrystalline Si (mc-Si) were investigated to obtain valuable information for the development of crystal growth technology of mc-Si ingots for solar cells. We newly developed an in situ observation system for the direct observation of crystal/melt interface at high temperature as 1400℃. The effect of grain boundaries on the crystal growth behaviors was clarified. On the basis fo the fundamental understanding of crystal growth mechanisms, we developed a crystal growth technology for mc-Si ingot. We obtained high quality mc-Si ingot in comparison with the conventional one.
ファセットデンドライト成長を利用した高品質薄板多結晶シリコンの成長技術の開発

藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(A)

Institution: 東北大学

2009 - 2011

More details Close

本研究では、薄板多結晶シリコンの成長技術を開発するための要素技術として、融液成長過程においてSi多結晶が成長するメカニズムを解明することを目的としている。本技術開発には、融液成長過程において、ファセットデンドライト成長を効果的に発現させることが重要となる。本年度は、昨年度に導入したシリコンの融液成長過程のその場観察装置を用いて実験を行い、Si融液から薄板結晶が成長する過程を直接観察し、特に、ファセットデンドライト成長メカニズムの解明において大きな成果が得られた。本装置を用いた実験により、Si<110>ファセットデンドライトの成長過程を詳細に観察することができ、その成長メカニズムを解明した(Phys. Rev. B, 81(2010)224106)。これにより、Si<112>ファセットデンドライトとの成長メカニズムの違いが明らかになった。また、ファセットデンドライトの成長速度の理論式を専出し、過冷却度がファセットデンドライトの成長速度に及ぼす影響を理論と実験の両方から明らかにした(Appl. Phys. Lett., 98(2011)012113)。過冷却度が同じ場合、<110>デンドライトの成長速度の方が、<112>デンドライトの成長速度より大きくなることが示された。また、過冷却度の大きさによって、<112>デンドライトと<110>デンドライトの発生割合が変化することが明らかとなった(Cryst. Growth Des., 11(2011)1402)。低過冷却度では<112>デンドライトの発生割合が大きく、高過冷却度では<110>デンドライトの発生割合が大きくなる。これにより、融液成長過程において、どちらか一方のファセットデンドライトのみ発現させるための知見が得られた。
電場印加による結晶成長界面の形状制御法の確立と薄板結晶Siの成長技術への応用

藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 挑戦的萌芽研究

Institution: 東北大学

2010 - 2010

More details Close

本研究の目的は、「電場を印加してSiの結晶-融液界面(成長界面)の形状を制御する」という独自の発想を具現化し、次世代太陽電池用材料として有力な薄板多結晶Siの高品質化成長技術への応用を検討することであった。双晶や粒界などの欠陥形成やデンドライトの発現は、成長界面の形状に強く依存する。つまり、成長界面形状を自在に制御する技術の開発こそが、薄板多結晶Siの組織制御のための根幹技術となる。本研究では、その場観察装置を用いて結晶成長過程の成長界面に電場を印加し、成長界面形状の変化を直接観察した。まず、融液成長中にシリコン融液および結晶に電流注入を行うことができる装置を作製した。電流注入量は1mAから100mAの範囲で制御を行った。しかしながら、シリコンの一方向中に電流注入を行っても固液界面形状または結晶成長速度に大きな変化は観察されなかった。そこで、固液界面形状を制御する方法として、第二元素の添加を試みた。本研究ではシリコンと同族のゲルマニウムを微量添加することで、界面形状の制御を行った。純シリコンでは、一方向成長過程の固液界面形状は、成長速度が約100μm/sec以下では平坦な形状を維持するが、それ以上の成長速度では界面不安定化によりジグザグ状のファセット界面が形成されることがわかった。次にゲルマニウムを1at%～15at%の範囲で添加して、一方向成長過程の界面形状を観察した。ゲルマニウムを1at%添加すると、界面形状が平坦からファセット界面へと変遷する成長速度が、純シリコンの場合より約半分程度になることがわかった。これは、組成的過冷却の影響で固液界面の不安定化が容易に起こることに起因する。当初目的としていた電場の効果は見られなかったが、第二元素の微量添加により界面形状を容易に制御可能であることがわかり、薄板結晶の作製に有用な知見が得られた。
Investigation of crystal growth mechanisms of Si crystals floating on Si melt and development of crystal growth technique to realize high-quality Si multicrystals

NAKAJIMA Kazuo, USAMI Noritaka, FUJIWARA Kozo, KUTSUKAKE Kentaro, MORISHITA Kohei

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (S)

Institution: Tohoku University

2008 - 2010

More details Close

We clarified fundamental crystal growth mechanisms of Si from melt such as formation mechanisms of microstructures and crystal defects by using an originally developed crystal growth furnace with in-situ observation system and model crystal growth experiments with purposely designed multi-seed crystals. The newly obtained fundamental knowledge on crystal growth mechanisms has been successfully implemented for development of floating cast method as a novel crystal growth technique to realize high-quality Si multicrystals with controlled microstructures and crystal defects, which will be utilized for high-efficiency solar cells.
方位・粒界・粒サイズを制御した太陽電池用バルク多結晶シリコンの成長技術の確立

藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(A)

Institution: 東北大学

2006 - 2007

More details Close

本研究の目的は、方位・粒界・粒サイズが制御された太陽電池用Siバルク多結晶インゴットの成長技術を確立することである。具体的には、申請者らが発案した「デンドライト利用キャスト法」により従来の多結晶よりも高品質な結晶を得ることである。本成長方法では、一方向成長の初期過程に坩堝底面に沿ってファセットデンドライトを成長させることが最も重要になる。本研究では、Siの融液成長過程のその場観察実験により、ファセットデンドライトが成長するための条件である、平行双晶の形成機構を明らかにし、さらにファセットデンドライトが成長するために必要な過冷却度を定量的に明らかにした。これらの基礎実験により得られた結果をデンドライト利用キャスト法の成長条件ヘフィードバックすることにより、15cmφのインゴットの成長において、成長初期に坩堝底面に沿ってファセットデンドライトを効果的に発現させるための条件を取得した。実際に、市販のSi多結晶と比較して、結晶方位が一方向に揃い、結晶粒サイズが大きく、Σ3対応粒界が多いSiバルク多結晶を得ることに成功した。この多結晶を用いて作製した太陽電池は、市販の多結晶太陽電池の変換効率を上回る特性を示した。さらに、従来の方法では結晶の品質が低下するインゴット上部においても高品質な結晶性を維持しており、歩留まりの向上に対しても有効な成長技術であることが証明された。この結果により、デンドライト利用キャスト法の実用大型装置への展開が現実味を帯びてきた。
Growth of bulk langasite crystal via manipulating the solid-liquid equilibrium phase relationship under an external electric field

UDA Satoshi, HUANG Xinming, KOH Sinji, SIMURA Rayko, FUJIWARA Kozo

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2005 - 2007

More details Close

[Purpose of the research] Develop a mechanism and technology to grow a bulk langasite (La_3Ga_5SiO_<14>:LGS) crystal via converting its incongruent-melting state to congruent by applying an externally electric field. [Achievements] 1. An external electric field modifies the chemical potentials of both solid and liquid phase by adding electrostatic energy that leads to a new equilibrium state in terms of temperature and composition. Based on this mechanism, the incongruent LGS was converted into congruent. The compositional dependence of the electrical permittivity of the phases around LGS composition determines whether or not such a conversion is possible. In the case of LGS conversion, the permittivity should increase toward the La-rich composition. 2. The conversion was successful experimentally when an electric field of 600 V/cm was applied. However, the analytical consideration shows as much larger electric field as 10^4-10^5 V/cm that may be sustained in an electric double layer (~nm) forming at the boundary of melt and platinum crucible wall or at the solid-liquid interface. 3. A floating zone furnace attached with an electric field imposition system was developed. LGS crystal of about 10 mm diameter was successfully grown in congruent manner under an externally applied field of 600 V/cm. 4. The effect of an electric field on the growth process of YBCO crystal via a peritectic reaction, i.e., 211 (Y_2BaCuO_5) + liquid->YBCO (123) was studied. The external electric field enhanced dissolution of the 211 gains, but had almost no effective electric field operating on the transportation process of the solute, and little effect was observed on the attachment kinetics. On the other hand, the external electric field increased the critical energy for the nucleation of the YBCO grains, which retarded the nucleation of the YBCO grains.
ゲルマニウム結晶ウェハーの高温加圧加工によるX線用モノクロメーター結晶の研究

中嶋一雄, 宇佐美徳隆, 藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 萌芽研究

Institution: 東北大学

2006 - 2006

More details Close

本研究では、高温加圧加工法により、X線の一点集光が可能なモノクロメーター用ゲルマニウム結晶レンズを作製することを目的とした。まず、既存の加工装置で、SiやGe結晶ウェハーの高温加圧加工が可能な条件・範囲を精密に決定した。加工温度、荷重、加工時間等をパラメータとして、系統的な加工実験を行った結果、融点近傍の温度において、ゲルマニウム単結晶ウエハーを任意の形状に加工できる条件が明らかとなった。また、面方位の異なるウエハーに対して、それぞれ加工性を調べた。いずれのウエハーに対しても、良好な加工を施せる条件が明らかとなった。高温加圧加工後の結晶に対して、透過電子顕微鏡観察により転位密度の測定を行った結果、より高温で変形した結晶ほど転位の導入量が少なく結晶性がよいことがわかった。この加工条件をベースに、曲率半径が30mm〜600mmの範囲の、さまざまな焦点距離を持つゲルマニウム結晶レンズの作製を試みた。これらの結晶レンズに対して、光学顕微鏡、電子顕微鏡観察およびX線回折により結晶評価を行い、設計どおりの曲率を有する結晶レンズが得られているか確認した。ウエハーのエッジ部において、変形量が不足する領域が存在するものの、概ね目的の曲率を有するゲルマニウム結晶レンズが得られた。実際にX線を用いて集光試験を行ったところ、ゲルマニウム結晶レンズの曲率に応じた焦点位置において、X線が集光することが確認された。
デンドライト成長を利用した完全配向半導体バルク多結晶の成長技術の開発

藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 萌芽研究

Institution: 東北大学

2005 - 2006

More details Close

本研究では、一方向成長キャスト法において成長初期過程にデンドライト結晶をルツボ壁に沿って成長させ、このデンドライト結晶上面にSiバルク多結晶を成長させる「デンドライト利用キャスト法」により、粒方位、粒サイズ、粒界性格を制御した太陽電池用Siバルク多結晶を作製することを目的としている。本年度は、キャスト成長の初期過程にデンドライト成長を効率的に発現させるために、第二元素としてGeを微量添加することを着想した。融液成長過程のその場観察装置を用いて、Si融液およびSiGe融液からの結晶成長過程を直接観察し、成長様式を比較した。Geを微量添加することによって、純Si融液の場合に比べてデンドライト成長が起こりやすくなり、かつ、デンドライト結晶のサイズも大きくなることが明らかとなった。これは、Geを添加することで融液中に組成的過冷却が生じたためであると考えられる。この知見をベースとして、キャスト成長においてもSiにGeを微量添加して5cmφ×3cmのバルク多結晶インゴットの成長を行った。Geを添加しない場合は、{112}面に配向したインゴットが得られたが、Geを添加したインゴットにおいては、{110}面に80%以上配向したバルク多結晶インゴットが得られた。これは、キャスト成長初期に、ルツボ底面に沿って<112>方向に伸びるデンドライトが多数成長したためである。このように、Geの微量添加により、バルク多結晶インゴットの組織制御が可能であることを実証し、特定の結晶方位に配向したバルク多結晶インゴットを実現した。
Growth mechanism of Si faceted dendrite Competitive

System: New Energy Technology Research and Development

2006/01 -
高温加圧法によるシリコン結晶ウェハーの変形加工と形状制御限界の研究

中嶋一雄, 藤原航三, 大平圭介

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 萌芽研究

Institution: 東北大学

2005 - 2005

More details Close

本研究では、硬くて脆いSi結晶を、三次元的に自由な形状に変形加工するための加工条件(加工温度範囲、ウエハー厚さ、荷重、形状、面方位)を明らかにし、Si結晶ウエハーの高温加圧加工と形状ウエハー結晶の利用という新しい研究分野を拓くことを目的とした。また、三次元的に加工したウエハー結晶の太陽電池やX線集光レンズへの応用を検討した。 Si(100)およびSi(111)結晶について、加工条件(加工温度、加工荷重、ウエハー厚み)を変化させて系統的に加工実験を行い、それぞれの結晶において、最適な変形加工条件を特定した。この条件を用いれば、板状の結晶を半球状や波状など三次元的に自由な形状に加工できることを実証した。また、本高温加圧加工法により、さまざまな曲率を有する半導体結晶レンズの作製に成功した。本手法により作製したSi結晶レンズを用いて太陽電池を試作し、加工条件と変換効率の相関を調べた。Si結晶レンズ太陽電池の変換効率は、加工温度や加工後のアニーリングにより結晶内の転位密度を低減することにより改善されることを示した。このSi結晶レンズ太陽電池を集光レンズ型太陽電池として応用した新しい太陽電池システムを提案し、本システムを用いることにより、太陽電池の変換効率を向上できることを示した。さらに、この半導体結晶レンズの表面の結晶格子面が曲率にあわせて変形することを見出し、この特徴を利用することにより、本手法により作製される半導体結晶レンズがX線用の一点集光レンズに応用できる可能性を示した。以上のように、本研究におけるSi結晶の3次元的加工という萌芽的な研究から、様々な応用分野への発展が期待できる成果が得られた。
多結晶シリコンの組織形成機構の解明および太陽電池用完全配向型多結晶シリコンの作製

藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(A)

Institution: 東北大学

2004 - 2005

More details Close

本研究は、太陽電池用高品質Siバルク多結晶の成長技術を開発することを最終目的として行われた。Siバルク多結晶の高品質化を実現するためには、結晶粒方位、粒サイズ、粒界密度などを制御する必要があり、これらを制御するための結晶成長メカニズムを明らかにしなければならない。本研究では、Siバルク多結晶の融液成長過程の直接観察装置を開発し[1]、本装置を用いた成長実験により、Siバルク多結晶の一方向成長初期過程において、デンドライト結晶を成長させる条件を明らかにした。デンドライト結晶は成長速度が速く、結晶粒の粗大化に有効であるだけでなく、デンドライト結晶上面の方位が限られた方位に限定されることから方位制御にも有効であることが判った[2]。この知見をキャスト法に適用したデンドライト利用キャスト成長法を提案した[2]。キャスト法によるSiバルク多結晶インゴットの一方向成長初期過程に、坩堝底面に沿ってデンドライト結晶を成長させることによって、インゴット下部においてデンドライト組織が形成される。これらのデンドライト結晶上面の方位は(112)面または(110)面に揃っており、このデンドライト組織上にバルク多結晶を成長させることによって、方位および粒サイズが制御された高品質Siバルク多結晶インゴットが得られた。このインゴットを用いて作製した太陽電池の変換効率は、従来のキャスト法で作製したSiバルク多結晶の太陽電池の変換効率を上回ることを実証した[3]。 [1]K. Fujiwara et al. J. Crystal Growth,262(2004),124. [2]K. Fujiwara et al. J. Crystal Growth (in press). [3]K. Fujiwara et al. Acta Materialia (in press).
Growth of High Quality Polycrystalline Silicon for Solar Cells Competitive

System: New Energy Technology Research and Development

2004/11 -
その場観察法による過冷却度の制御および過冷却シリコン融液からの結晶成長機構の解明

藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 東北大学

2001 - 2002

More details Close

本研究の目的:太陽電池用の多結晶シリコンは融液成長により作製されているが、その成長機構はあまり理解されていない。本研究では、1500℃までの範囲で温度制御できる小型炉と顕微鏡を組み合わせた、融液成長過程その場観察装置を新たに作製した。本装置を用いてシリコンの融液成長過程を直接観察し、成長機構を明らかにした。結果:まず、方位が既知の種結晶を用いて成長界面形状の成長方位依存性を調べた。(111)種結晶を用いた場合、成長界面はフラットであるが、(100)種結晶では、成長界面にファセットが形成した。次にこの二種類の種結晶を並列に配置し、両方の種結晶から同時に成長を行った。冷却速度が5℃/minと遅い場合、それぞれの方位から成長した結晶粒の成長速度は同程度であった。一方、冷却速度を100℃/minと速くした場合、(100)から成長した結晶粒の方が約1.3倍成長速度が速かった。このような成長の場合、成長速度が速い結晶粒が成長に伴い遅い結晶粒を覆うように、成長方向と垂直方向にも成長する過程が観察された。つまり、冷却速度が速い場合、融液の過冷却度が大きくなり、結晶方位による成長速度の差が顕著になる。従って、結晶成長過程において競争的結晶粒成長が起こることが明かとなった。また、種結晶を用いずに速い速度で冷却した場合、不安定な成長界面の突起部から急激に成長する異常成長が観察された。まとめ:シリコンンの融液成長過程の直接観察に成功した。シリコンの融液成長において、融液の過冷却が大きくなると結晶方位による成長速度の差が大きくなり、成長の速い結晶粒が成長の遅い結晶粒を覆うように成長する競争的結晶粒成長が起こる。このことは多結晶シリコンの方位制御技術に利用できる知見である。
過冷炉度を制御した融液成長法による太陽電池用Si多結晶の大粒径化と高効率化

中嶋一雄, 宇治原徹, 佐崎元, 宇佐美徳隆, 北原邦紀, 藤原航三

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(A)

Institution: 東北大学

2001 - 2002

More details Close

研究目的:多結晶シリコンは実用太陽電池材料として利用されているが単結晶材料に比べてエネルギー変換効率が低い。その原因として、結晶粒界や転位や不純物など結晶欠陥の影響が考えられている。このような結晶欠陥は融液成長時に導入されるが、その制御方法は確立されていない。本研究では融液成長時の過冷度を精密に制御して成長を行い過冷度や潜熱と結晶欠陥および結晶粒径の相関を解明する。本年度の実績:本年度は融液成長過程および成長温度を同時に観察できる装置を設計・導入した。本装置は観察窓付きの一方向成長特殊小型炉と赤外線放射温度計を組み合わせた装置である。小型炉は高真空に引いた後アルゴンガス置換でき、冷却速度および炉内温度を精密制御できる。また、冷却ガスによる強制冷却機構と種付け機構を有する。さらに示差熱検出機構を有している。放射型温度計は顕微機構を有し、赤外と同時に高速度CCDカメラで可視像を観察できるため、成長過程と温度を同時に測定できる。試料サイズは10×15×5mm^3程度であり、成長後組織解析を行うのに十分な大きさである。予備実験としてレーザー顕微鏡とイメージ炉を組み合わせた装置を用いてシリコンの融液成長過程をその場観察した。φ3×2mm^3の試料を融解後さまざまな速度で冷却し界面の形態および成長速度を実測した。3K/minで冷却した試料の成長界面はplanar界面であったが25K/min、40K/min、および45k/min冷却した試料ではfacet界面であった。定常状態における成長速度はplaner界面ではV【less than or equal】30μmであったがfacet界面では150μm【less than or equal】V【less than or equal】390μmであった。また非定常状態ではfacet面の消滅過程も観察された。非定常状態ではさまざまなfacet面が形成されたが(111)facet以外の面は消滅し、定常状態では(111)facetのみ形成した。また、赤外線カメラを用いてfacet界面前方の温度測定を行った。界面前方の過冷度はおよそ7度であった。
Structure control of silicon-germanium alloy Competitive

2001/09 -
Investigations of melt growth behavior of polycrystalline silicon Competitive

System: New Energy Technology Research and Development

2000/09 -

Show all Show first 5

Social Activities 1

福岡県立鞍手高校SGH スーパーグローバルハイスクール講義

2015/09/29 - 2018/09/30

More details Close

鞍手高校のSGH事業では、普通科人間文科コースを中心に、筑豊地域に関する研究やアジア地域の研究を進めることによって、グローバルな視点で地域の発展や課題解決のために貢献しようとするグローバルリーダーを育成することを目的としています。本講義では、「資源・エネルギー・環境問題を考える－太陽電池用材料の先端研究－」と題して、太陽光発電の現状と未来を中心に講義を行った。