Photoluminescence study of InAs/AlAs quantum dots

Self-organized InAs quantum dots: (QDs) embedded in an AlAs matrix are inve stigated by photoluminescence (PL) and photoluminescence excitation spectro scopy (PLE), For InAs coverage of about 2.0 ML, a PL peak is observed at en ergies slightly below 1.6 eV and attributed to radiative recombination from the QD ground states. At higher excitation intensity two additional peaks occur at 80 and 140 meV above the ground state, which we attribute to PL fr om excited QD states. Transmission electron microscopy (TEM) images show a high QD density of 1 x 10(12) cm(-2) resulting in small inter-dot distances , which hints to lateral coupling of the QDs.