An effect of size fluctuation on photoluminescence peak width of closely stacked InAs self-assembled quantum dot structures

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We studied the effect of size fluctuations on the photoluminescence (PL) peak widths of closely stacked InAs self-assembled quantum dot structures. We calculated the PL spectra of InAs quantum dot structures using three models based on the effective mass approximation method and compared them with experimental values. Our calculations showed that the PL peak width is predominantly determined by height fluctuations. We obtained the dependence of the full width at half maximum (FWHM) on the intermediate layer thickness d for 2-layer stacked structures from d=2 nm to 6 nm to clarify effect of vertical coupling. The FWHM increases with a decreasing d. A decrease of FWHM with a decreasing d is seen in the region where the number of vertically connected islands increases. We observed a very sharp PL peak for a 3-layer stacked structure, which is attributable to an extremely reduced island height fluctuation as well as vertical coupling.