Crystal quality and impurity segregation of semiconductor crystals grown under microgravity
| Project/Area Number |
06452106
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | University of Tokyo |
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Principal Investigator |
NISHIMAGA Tatau University of Tokyo, Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (10023128)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Masaaki University of Tokyo, Graduate School of Engineering, Assoc.Professor, 大学院・工学系研究科, 助教授 (30192636)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1995: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Microgravity / GaSb / Te impurity / Spatially Resolved photoluminescence / Segregation / Marangoni flow / Burstein-Moss effect / Bridgman growth / 中国回収型衛星 / フォトルミネッセンス / 不純物縞 / 転位密度 |
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| Research Abstract |
GaSb single crystal grown by Chinese recoverable satellite No.14 was characterized by chemical etching and spatially resolved photoluminescence. The crystal doped with Te was grown by Bridgman technique under microgravity. The grown crystal was cut longitudinally along the growth direction <111>, into two parts and among them one piece was further cut perpendicular to the growth direction. Each sample was polished mechanically and chemically etched to reveal impurity striations, twin or grain boundaries and dislocations. It was demonstrated that impurity striations are present in the earth grown part while they are absent in space grown part. It was also found that the dislocation density goes to zero in the space grown part where the melt did not touch with the ampoule wall but it increases steeply in the part where strong contact with the wall occured.
The concentration distribution of Te was measured by using the spatially resolved photoluminescence (SRPL). The measurements of spatially resolved photoluminescence were carried out point by point from the earth grown seed part to the regrown part along the growth direction. It was found that the concentration of Te decreases abruptly at the interface between the seed ant the regrown part. Then, it increases rapidly to the impurity level of the seed region. The profile shows that the impurity doping occured in pure diffusion control and this suggests that Marangoni convection was stopped as well as the thermal convection.
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Report
(3 results)
Research Products
(28 results)
