Controlling the optical transition linewidth of a self-assembled quantum dot ensemble

Summary form only given. It is now possible to control quantum dot (QD) size, composition and shape by optimizing fabrication parameters. However it is still difficult to control the linewidth of the optical transition and hence the gain of the QD lasers. The width of the photoluminescence (PL) peaks is generally assigned to QD inhomogeneities (size, shape, composition or strain) within the large ensemble. It is important to acquire a better understanding of the influence of each structural parameters on the energy of the QD levels in order to focus our research effort on ways to minimize fluctuations of the key parameter which limits the narrowing of the QD PL peaks. We have investigated the PL linewidths of as-grown and intermixed selfassembled QDs. We show typical spectra obtained for two samples. A blue shift of the optical transitions is observed when intermixing is carried out together with a reduction of the full-width at half maximum.