| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1999: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Heteroepitaxial growth of insulating layers on Si and the successive growth of a single crystalline Si on those insulating layers are of great interest in the formation of silicon-on-insulator (SOI) structures. We have proposed γ-Al2O3 films as an insulator material and obtained high quality layers of γ-Al2O3 on Si substrates. In our group, we have already studied SOI(Silicon On Insulator) structures, and have proposed an epitaxial γ-Al2O3 film as insulator material. The epitaxial growth of γ-Al2O3 was investigated with the hybrid source MBE using Al solid source and N2O gas source. Very thin and very flat γ-Al2O3 films without carbon contamination were grown on Si substrates successfully by the hybrid source MBE.This structure is suitable for the usual Si process due to stable Al2O3 insulator. So γ-Al2O3 is being expected of an insulation film which can be substituted for SiO2. At present, our group are studying application to MIS type Field Emitter of γ-Al2O3. Furthermore, applicatio
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ns to quantum effect devices can be expected because multiple layer structure by Si and γ-Al2O3 can be formed easily. The very thin film growth control of γ-Al2O3 and Si becomes very necessary to form a quantum well structure. Therefore, the purpose of this study is the growth control of nm-thickness, and the formation of the quantum well structure by Si and γ-Al2O3. The quantum well structure composed of Si and an insulation film can be expected to lock up electrons of the high energy, because an insulation film with a large barrier height to Si was used. So the quantum well structure by Si and γ-Al2O3 has a potential application to an emitter which can emit a constant electron energy. As a result of the calculation, the thickness control of the Si film in less than 4nm must be realized. As growth of γ-Al2O3, an electrical insulation property of directly grown γ-Al2O3 on the Si was poor. But about 5MV/cm was realized using a 3nm-thick γ-Al2O3, which was prepared by Al2O3 pre-layer method. The γ-Al2O3 growth control of very thin film (3nm-thick) with good insulation property was realized by this growth method. Until now, Si2H6 gas sauce was used for the Si growth, but the control of film thickness of a few nm was impossible. So, the Mini-beam evaporator device with a low growth rate was introduced. So low speed growth (4nm/hour) became possible by this method. But a problem in Si surface flatness was still remained. So we proposed that termination of a γ-Al2O3 surface with Al, which is at first, deposition of Al, then annealing with 800℃. By this method, at the early stage of the Si growth, we succeeded in the repression of three-dimensional growth of Si. A γ-Al2O3 (3nm) /Si (lll) (4nm)/γ-Al2O3 (3nm)/Si (lll) structure was formed with Al2O3 pre-layer and Al pre-deposition. Then, the electrical characteristics were evaluated. As a result, a negative resistance was confirmed at room temperature. Less
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