Carrier-Density- and Excitation-Energy-Dependent Γ-X Photoluminescence of Type-II GaAs/AlAs Superlattices

Recently, "Type-II" semiconductor superlattices characterized by a "staggered" alignment of the valence and conduction bands have attracted much interest.1-5 Considerable effort has been directed toward understanding the optical properties of these structures. We focus our attention on a subclass of GaAs/AlAs superlattices in which quantum size effects produce the staggered Type-II band structure as illustrated in Figure 1. Although the linear optical spectroscopy of these structures is fairly well understood, to date there is a paucity of research on their nonlinear optical properties and inter-subband and inter-layer relaxation dynamics.