| Co-Investigator(Kenkyū-buntansha) |
MATSUSUE Toshio Institute of Industrial Science, University of Tokyo, Research Associate, 生産技術研究所, 助手 (20209547)
NODA Takeshi Institute of Industrial Science, University of Tokyo, Research Associate, 生産技術研究所, 助手 (90251462)
NAGAMUNE Yasushi Research Center for Advanced Science and technology, University of Tokyo, Resear, 先端科学技術研究センター, 助手 (20218027)
ARAKAWA Yasuhiko Institute of Industrial Science, University of Tokyo, Professor, 生産技術研究所, 教授 (30134638)
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| Research Abstract |
As for artificially localized states, namely, the magnetic quantum box (Mag-QB) systems consisteing of quantum wells at magnetic fields, Coulomb quantum box (Imp-QB) systems formed at impurity, levels in quantum wells, and quantum boxes by nanofabrication technique (Fab-QB), we have studied following three subjects.
First, we observed longitudinal magnetophonon resonances in superlattices, tunnelling processes through Landau levels in triple barrier tunnel diodes at magnetic fields, and two-dimension (2D) -0D-2D tunnelling through donor levels in double barrier tunnel diodes. In addition, we observed turnstile motion and photon-assisted tunnelling in an electron-beam-fabricated QB.We also fabricated self-assembled InAs quantum boxes and carried out transport measurements.
Second, we examined energy relaxation in super-donor levels in order to clarify presence of phonon bottle-neck both theoretically and experimentally. Our theory showed existence of phonon bottle-neck, and Bloch oscillations in 1D coupled quantum box structures due to suppression of phonon scattering. However, the possibility of relatively fast decay within a few meV at resonance relating to both optical and accoustical scatterings were demonstrated. Experimentally, both transport properties of a triple barrier resonant tunnel structure at magnetic fields and optical analysis of a fast relaxation process in electron-hole systems in quantum wells at magnetic fields suggested presence of fast relaxation process.
Third, as for photon excitation and ionization of super-donor states, we investigated controllability of donor levels, temperature dependences of conductivity, and infrared response by introducing Si acceptors in (311) A quantum wells.
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