1998 Fiscal Year Final Research Report Summary
Fabrication of novel functional surfaces through ionic crystal / semiconductor heterostructurse and their properties
| Project/Area Number |
09450006
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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 | The University of Tokyo |
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Principal Investigator |
SAIKI Koichiro The Univ.of Tokyo, Graduate School of Science, Associate Professor, 大学院・理学系研究科, 助教授 (70143394)
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| Co-Investigator(Kenkyū-buntansha) |
UENO Keiji The Univ.of Tokyo, Graduate School of Science, Assistant, 大学院・理学系研究科, 助手 (40223482)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Epitaxy / Ionic crystal / Alkali halide / GaAs / MgO / Ultrathin film / Interface strain / Photoyield |
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| Research Abstract |
The results of the present research are summarized.
(1) Initial oxidation process of Mg and Ba films studied by electron spectroscopies
MgO and BaO, which are lattice matched to GaAs and Si, could be expected to be key materials to integrate functional perovskite oxides with highly developed semiconductor technologies. In the present work we have revealed the initial oxidation process of Mg and Ba films using Auger electron spectroscopy, electron energy loss spectroscopy and ultraviolet photoelectron spectroscopy. The conditions of oxidation such as critical oxygen exposure, appropriate substrate temperature, etc. have been clarified.
(2) Evaluation of alkali halide hetero-interface by high sensitive RHEED analysis
The interface of alkali halide heterostructures have been analyzed by reflection high energy electron diffraction (RHEED). The disadvantage of this method is that the probing electron causes damage to the growing film. In the present work we have devised high sensitive RHEED app
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aratus using micro channel plate (MCP), which could reduce the probing current by as much as 1/8000. With this apparatus we could observe the initial growth process of alkali halide films and clarified the mechanism in detail.
(3) A complex heterostructure to achieve a rocksalt oxide film on GaAs
A single-crystalline MgO film was grown on GaAs(001) by constructing a complex heterostructure with two alkali halide buffer layers. The growth temperature was decreased to 150 ﾟC as compared with direct growth of MgO on GaAs(001). Electron energy loss spectrum of the grown film agreed well with that of bulk MgO, indicating that surface stoichiometry was maintained. The structure was stable up to 600ﾟC against heating in UHV condition. The concept of a complex heterostructure will help fabrication of functional oxide layers on GaAs substrates and lead to oxide/semiconductor integrated devices.
(4) Photoyield measurement of alkali halide/semiconductor heterostructure
We have devised a new apparatus to measure a photoyield from the film surface. The photoyield from the NaCl/GaAs heterostructure with various NaCl thickness have been measured up to now. This provides the photo threshold for the electron emission and additive information on the band alignment of the exotic heterostructure such as NaCl/GaAs. Less
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