Theory of excitonic photoluminescence linewidth in semiconductor alloys

Abstract

An expression for the excitonic photoluminescence linewidth in intentionally undoped semiconductor alloys is derived. The dominant mechanism for the line broadening is due to the statistical potential fluctuations caused by the components of the alloy. These fluctuations are accounted for by using statistical arguments developed by Lifshitz and then related to the linewidth. Compositional dependence of the linewidth is derived. It is shown that the linewidth is strongly dependent on the short range disorder present in the alloy. The theoretical results are compared with the available low-temperature photoluminescence data in GaAlAs.