Temperature dependence of the exciton population in emission spectra of GaAs single quantum wells with enlarged monolayer-flat growth islands

Abstract

The temperature dependence of the exciton population is investigated in GaAs single quantum wells (SQW) 19–22 monolayers wide with enlarged monolayer-flat growth islands grown by growth interrupted molecular-beam epitaxy. A comparative study with in-plane photocurrent spectroscopy shows that free-excitonic recombinations within the growth islands dominate the emission spectra even at room temperature. Detailed studies of the lowest heavy-hole exciton spectral characteristics as a function of the lattice temperature allow us to directly find the in-plane exciton localization and exciton detrapping processes between the SQW growth islands. A simple model analysis was made to explain observed temperature-dependent variations of the population at the exciton bands corresponding to the four different SQW growth islands, assuming Gaussian line-shape functions.