Evolution of the energy levels in quantum dot ensembles with different densities

Ensembles of self-assembled InAs/GaAs quantum dots (QDs) have been obtained with different densities by molecular beam epitaxy. The evolution of the s tructural and optical properties with coverage shows that lateral interacti ons are present for QD spacings of hundreds of nanometers (coverage > simil ar to 10(9) QDs/cm(2)). Clear evidence for transfer of InAs from the wettin g layer to the QDs is observed at the onset of the Stranski-Krastanow's isl and formation for 1.83 monolayers (MLs). QDs with sharp electronic shell st ructures are observed by state-filling spectroscopy for the low density ens embles (1.83-1.91 ML). A decrease in the photoluminescence intensity is obs erved for more than 1.96 ML and is associated with the coalescence of the i slands. (C) 1999 American Institute of Physics. [S0003-6951(99)03139-3].