Finite Carrier Confinement and Biexcitonic Complexes in Self-Assembled Inas Quantum Dots

The luminescence properties of a single lnAs self-assembled quantum dot (QD) are studied by confocal scanning optical microscopy at low temperature. The observation of single QDs has been accomplished by epitaxial growth of QDs samples with low QD density (less than one QD per μm2) required by the diffraction limited spatial resolution of the microscope. In thick QDs with large confinement energies biexciton binding energies of up to 5.0 meV are found, while in thin and more weakly confined QDs the electron wavefunction penetrates into the surrounding barriers causing reduced biexciton binding energies of less than 2.0 meV. This result can be understood in terms of theoretical calculations of biexcitonic complexes in QDs with finite potential barriers.