A RESEARCH ON QUANTUM DOT BASED MATERIAL FOR WAVELENGTH-DIVISION-MULTIPLICATION MEMORY APPLICATIONS

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Now it is possible to form quantum dots in which electrons show its wavenature as their discrete energy levels. So far, however, the size of the dots is not uniform. This study aim at using those inhomogeneous quantum dots for wave-division-multiplication optical memory based on the fact that quantum dots respond to light with a specific wavelength corresponding to its size.We discovered scaling functions of the size distribution and the position distribution of the InAs/GaAs self-assembled quantum dots(SAQDs)grown by molecular beam epitaxy(MBE). This indicates that the mechanism governing the formation of the dots is described by a rather simple picture.We studied a possibility to enhance the memory duration using tunneling effect, and confirmed the tunneling of the electrons from InAlAs SAQDs through an AlGaAs tunneling barrier to the AlAs layer. Also, we showed possibilities to increase the effective density of dots using a stacking technique.The lattice deformation and atomic diffusion of the InAs/GaAs SAQD were studied by ion channeling method. It was shown that the Ga diffusion depended strongly on the InAs coverage and that there were two regions of growth modes identified : one with larger dots with little Ga diffusion and the other with smaller dots with evident Ga diffusion.