A research group led by Professor Ichiro Yonenaga at Institute for Materials Research (IMR, Director Kazuo Nakajima,) Tohoku University (President Akihisa Inoue, Ph.D.) has devised a new method to grow germanium semiconductor crystals, and succeeded in growth of defect-free and high quality crystals.  Old grown crystal has included defects called dislocations of high-density caused by germanium oxides on the surface of melt while crystal is growing.  The research group has closely studied elementally reactions and properties in melt, devised an easy and elegant method to completely eliminate germanium oxides by partially covering the melt surface with B2O3, and grown dislocation-free and high-quality crystals.


Ge is being expected as a material for next-generation high-speed electron devices and solar cells.  The newly developed method to control dislocation by adding B2O3 will contribute to development of electronics and energy fields.  This technology economically grows Ge crystal that helps production of precise, long-lived, and high-speed devices, and highly-efficient energy exchange of solar cells


The research has been conducted by a grant for scientific research from Ministry of Education, Culture, Sports, Science and Technology.


The research results will be published in “Journal of Crystal Growth” as Priority communication soon.  The paper’s title is _ Reduction of grown-in dislocation density in Ge Czochralski-grown from the B2O3-partially-covered Ge melt._   Details will be and has been presented at The 70th Autumn Meeting, 2009, The Japan Society of Applied Physics at University of Toyama through September 8 to 11, 2009 and at The 39th National Conference on Crystal Growth (NCCG-39), Japanese Association for Crystal Growth at Nagoya University through November 12 to14, 2009.


[Contact]
Professor Ichiro Yonenaga
Institute for Materials Research (IMR,) Tohoku University
Address: 2-1-1 Katahira Aoba-ward Sendai, Miyagi, 980-8577, Japan
Tel: +81-22-215-2042
E-mail: yonenaga@imr.tohoku.ac.jp


Assistant Professor Toshinori Taishi
Tel: +81-22-215-2044
E-mai: taishi@imr.tohoku.ac.jp