Fabrication and Characterization of Atomic Layr Controlled Quantum Nano-structures

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Advanced technologies of controlling low-dimensional quantum structures (i.e.size, shape, composition, arrangement and doping control) with atomic-level accuracy were developed, based on atomic layr epitaxy (ALE) selective gwowth, for the future quantum devuces. The results o this study are summarized as follows.(1) Growth mechanism of localized-ALE in nano-space, and layr-by-layr growth mode switching techniqueIt has been found that ALE selective growth makes the control of semiconductor structures possible even in nanometer scale area (Localized-ALE), which is due to the self-limiting effect. Also layr-by-layr growth mode switching technique between anisotropic and isotropic ALE growth, using control of the growth sequence, was developed with the concept as a "selective-control of surface-processes".(2) Development of fabrication processes of low-dimensional quantum structures using ALE growth mode switching techniqueFabrication processes of low-dimensional quantum structures were de … More veloped, and rectangular shaped quantum wire structures were successfully realized. In this study, the fabrication of low dimensional atomic layr short-period superlattice by using the advanced ALE techniques were demonstrated, for the control of "conposition" and "arrangement" in quantum nano-structures.(3)Development of Digital-etching : Control of surface reaction by tunable UN laserDigital-etching of GaAs using tunable UV laser was discussed. It was found that alternative procedures between feed the enchant (Cl_2) and laser beam irradiation with precious wavelength is necessary to realize the self-limiting effect in digital etching process.(4) Observation and analysis of quantum size effects in low-dimensional quantum structures.Photoluminescence (PL) measurements on GaAs/GaAsP rectangular shaped quantum wires have been performed. One dimensional (1D) confinement effect on the structures has been confirmed by the PL emission and the polarization dependence of the PL spectra. Also the particular electronic states on valence band in the wires, whhich is due to the band mixing effect, was observed by the PL emission from the p-type modulation doped wire structures. Diamagnetic shift of PL emission from the wires also observed. Less