New Quantum Optoelectronic Properties of Semiconductors with Disordered Structures

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Remodeling has been requested to observe the cleaved surface of semiconductors with disordered structures by the ultra high vacuum scanning tunneling microscope. After several times of discussions with manufacturers, the remodeling which does not deteriorate the function of the surface observation was invented. It becomes possible to work continuously the research project.The stacked layrs of InAs/GaAs quantum dots were grown to investigate formation condigions for ordering or disordering assembling. The thickness of GaAs spacer is varied, since the spacer thickness affects to the strength of dot coupling. Through the observations of high resolution electron microscope, we obtain the following results : (1) quantum dots couple each other and assemble orderly if the spacer thickness is between single and twice much of the dot height, (2) they are destroyed if the spacer thickness is thinner than the dot height, (3) they do not couple and assemble disorderly if the spacer thickness is th … More icker than the dot height. The saturation in luminescence intensity is increased by the stacked layrs of InAs/GaAs quantum dots.The pahse separation in InGaN was experimentally discovered. This separation could be utilized for the dot formation of InN in GaN matrix. The size reduction is left as the future subject. The growth of the AIN layr is now investigated to see the effect of plasma exitation on the luminescence properties.Quantum dots have ben fabricated through the Stranski-Krastanov growth modein which three dimensional islands begin to be formed at the certain thickness of two dimensional layr : a transitional thickness. The analytical equation was derived in this study by taking the strain and the surface energy of the islands and the dots into account. The teoretical reults agree well with the experimental results. The equation can be applied to other heteroepitaxial systems.There are some properties of disordered superlattices which have not been characterized yet such as electron mobility. When the low electron mobility is observed, it indicates the localizations of electrons by disordering. Shanghai Institute of Technical Physics has offered to characterize it. The collaboration scheme will be continued. Less