Photolumineseenee of ZnO single crystals: Influence of <i>k</i>‐linear interaction and non‐analytic long‐range exchange on the emission spectrum of the free A‐exciton

Abstract

Abstract The effect of the non‐analytic long‐range exchange interaction as well as the k ‐linear interaction on the photoluminescence spectrum of the free A‐exciton in ZnO is investigated. By varying the angle between wave vector and crystallographic c ‐axis in uniaxial crystals one is able to “switch on and off” and to vary the coupling strength of these interactions. In order to avoid refraction complications connected with non‐perpendicular incidence the measurements are carried out at crystal planes inclined under different angles to the crystallographic c ‐axis. This method enables to observe and to study systematically the influence of k ‐linear terms and non‐analytic long‐range exchange on the emission spectrum for the first time without an external field.