Influence of stacking disorder on Wannier excitons in layered semiconductors

Abstract

The influence of stacking disorder on Wannier excitons in layered semiconductors is discussed. In particular it is found that in the presence of stacking disorder the excitons are confined to a finite number of layers. The experimental results are discussed for GaSe. In this case the absorption spectra turn out to be strongly sample dependent. In general they show a pronounced fine structure near the exciton groundstate energy, which can be understood as a consequence of the disorder-induced localization of the excitons. The variety of absorption spectra observed in GaSe can be related to the different stacking orders occurring in this material.