Photoluminescence study of interface microroughness and exciton transfer in growth-interrupted single quantum wells

Photoluminescence (PL) spectroscopy is used to study the interface disorder and interface exciton transfer in single quantum wells of various well widths grown by MBE with different growth interruption times. Growth-interruption-induced microroughness on the interface terraces gives rise to peak splitting in the PL spectra with energy spacings that correspond to less than 1 ML width difference. We were able to use the well width dependence of the number of split peaks and the ratios of integrated PL intensity as an optical probe to determine the terrace areas and deduce the probability distribution of the interface roughness. Furthermore, a detailed study of the change in relative intensities of the various peaks in PL spectra taken at varying temperature reveals intra-well transfer of excitions among the localization regions and inter-well transfer. The intra-well transfer corresponds, in terms of energy, to either relaxation (by emission of an LO phonon) or thermal population (via phonon absorption). (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)