1997 Fiscal Year Final Research Report Summary
Crystal Structures and their phase stabilities of mesoscopic order and disorder phases in III2VI3 compound semiconductor containint structural vacancy
| Project/Area Number |
08455011
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
NAKAMURA Yoshio Tokyo Institute of technology, Department of Engineering, Associate Professor, 工学部, 助教授 (00164351)
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| Project Period (FY) |
1996 – 1997
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| Keywords | compound semiconductor / long period superstructure / mesoscopic / structural vacancy / satellite reflection / X ray diffraction / electron microscopy |
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| Research Abstract |
One of the basic structures of III2VI3 compound semiconductors is zincblend structure and one third of cation sites of III2VI3 compounds are vacant. We have found a long period super structure appears in the Ga2Te3 annealed at 785ﾟC having 3 dimensional planer defects with periodicity of every ten {111} planes. On the basis of image contrast calculation and geometrical consideration, the origin of the periodic planer defects is found to be agregated structural vacancies which locate in 1/3 of cation sublattice. That is, although Se sublattice is perfect FCC,the crystal consists of tetrahedraons anf octahedrans whose outer surfaces are all {111} vacancy planres, and structure of the area which are surrounded by vacancy planes is nomal zincblend structure.
In this structure, vacancy content is imhpmogenious on the unit cell scale, but homogenious on the mesoscopic area in which several ten thousands of exsists. The phase is no longer simple order phase and is recognized by mesoscopic or mesoscopic order phase. The main stabilization mechanism of the mesoscopic compound semiconductor is to form four fold group VI atoms as much as possible. For the question why the vacancy planes periodically aline, however, clear explanation is not given.
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