| Co-Investigator(Kenkyū-buntansha) |
MACHIDA Nobuya Graduate School of Science and Engineering, Tokyo Institute of Technology, Research Assistant, 大学院・理工学研究科, 助手 (70313335)
ISHIHARA Michihiko Tokyo Metropolitan University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (80251635)
MIYAMOTO Yasuyuki Graduate School of Science and Engineering, Tokyo Institute of Technology, Associate Professor, 大学院・理工学研究科, 助教授 (40209953)
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| Research Abstract |
Analysis of Electron Wave Biprism Controlled by Buried Metal
Analysis of electron wave biprism proposed by a collaboration between Japan and Sweden has been proceeded. Especially, we have theoretically examined influences of coherence of electron source on contrast of interference pattern and it has been revealed that a highly coherent source emitting electron beam with a transverse energy spread of sub meV has been required to realize interference by the biprism. To realize such highly coherent electron beam, a coherent emitter, where a energy difference between a resonant level of a quantum well and a Fermi level of a source has been precisely controlled by a back gate, has been proposed and theoretically proved its operation principle.
Improvement of Isolation Technique on Formation of Periodic Fine Electrodes with Period of a Few Tens nm
For observations of electron wave phenomenon in the biprism by periodic fine electrodes with period of a few tens nm, it has been shown that isolatio
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n between electrode has been very important on small interference current measurement, and the required isolation has been achieved by conduction band discontinuity of heterojunction and dry etching.
Demonstration of Attractive Potential Formation by Buried Metal Hot Electron Transistor with Metal Wire Gate
We have proposed a novel transistor where hot electrons are generated and travel through undoped semiconductor region by adopting a combination of double-barrier resonant-tunneling structure and metal wire, and we has attempted to demonstrate attractive potential formation required in operation of the biprism by our proposed transistor. After fundamental studies of crystal growth for resonant-tunneling structure and burying metal in semiconductors, we have fabricated the device by re-growth to bury Tungsten in GaAs using OMVPE. By analysis of measured data, for the first time, a formation of attractive potential around the buried metal wife has been demonstrated. Furthermore, to reduce emitter-gate leakage current, we have fabricated transistors on InP semi-insulating substrate and wired by free-standing wire. From measured I-V characteristics, it has been shown that buried metal wire gate has enabled to produce attractive potential and leakage current has been reduced by examining value of peak current at negative differential resistance. Therefore,we have been able to show the potential of our device. Less
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