1999 Fiscal Year Final Research Report Summary
Fabrication of their properties
Grant-in-Aid for Scientific Research (A)
|Allocation Type||Single-year Grants |
Applied materials science/Crystal engineering
|Research Institution||The University of Tokyo |
KOMA Atsushi Graduate School of Science, The Univ. of Tokyo, Professor -> 東京大学, 大学院・理学系研究所, 教授 (00010950)
SHIMADA Toshihiro Graduate School of Science, The Univ. of Tokyo, Lecturer, 大学院・理学系研究所, 講師 (10262148)
UENO Keiji Graduate School of Science, The Univ. of Tokyo, Assistant, 大学院・理学系研究所, 助手 (40223482)
SAIKI Koichiro Graduate School of Frontier Science, The Univ. of Tokyo, Professor, 大学院・新領域創成科学研究科, 教授 (70143394)
|Project Period (FY)
1998 – 1999
|Keywords||Epitaxy / Ionic crystal / Molecular materials / Oxides / Complex heterostructure / Ultrathin film / Selective Growth / Electronic Structure|
This project has aimed at establishing techniques necessary to fabricate highly heterogeneous crystalline structures among various materials from inorganic to inorganic and from insulators to superconductors. Novel physical properties are being found from those exotic structures.
(1) 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℃ 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℃ 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.
(2) Epitaxial growth and phase transition of liqui
d crystal monolayers
Monolayer films of liquid crystals on single-crystalline inorganic substrates are expected to reveal novel properties involving phase transitions in two dimensions. It was found that liquid crystal 12CB can be grown epitaxially on alkali halide (OO1) surfaces. Temperature dependence of the film structure was investigated by using high-sensitive reflection high energy electron diffraction and atomic force microscopy. The shape of the monolayer boundary drastically changes with the substrate temperature near the transition temperature of 12CB.
(3) Selective growth of molecular materials for quantum structures
Selective growth is the only practical method to fabricate well-defined nanostructures of molecular materials in large scales. Difference in the stabilization energies at film-substrate interfaces is essential to achieve high selectivity. Two guiding principles have been established. One is the use of lattice matching of the grown film and the substrate materials which is found among ionic substrate materials. The other is the use of different van der Waals interaction which is found using layered materials.
(4) Physical properties of ultrathin films and heterostructures
Physical properties of fabricated structures were measured and novel properties are being revealed. For example, MnPc ultrathin film shows magnetic properties different from bulk single crystals due to different molecular arrangement. Less
Research Products (18 results)