Luminescence Properties of Periodic Disordered Thin Layer GaAs/AlAs Superlattices

Abstract

Disordered thin layer GaAs/AlAs superlattices with various disorder periods have been grown using MBE. The disorder was introduced by varying the thickness of GaAs and AlAs layers in the growth direction in various specific but randomly generated finite disorder sequences. The photoluminescence spectra of these disordered superlattice samples showed a sharp peak at the high energy side and a broad peak at the low energy side. The temperature, excitation, and disorder sequence dependence of the photoluminescence spectra indicates that the sharp peak is due to the pseudo-direct exciton emission, and the broad peak is strongly related to the localized states induced by disorder. In addition, the results demonstrate that the luminescence intensity of disordered superlattices can be improved by up to two orders of magnitude over that of ordered short period superlattices. Finally, we propose a kinetic model for the state population and find that the photoluminescence spectra can be well described by this model.