Optical Properties of GaAs/AlAs Short Period Superlattices

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Abstract
Low temperature photoluminescence (PL) and photoreflectance (PR) measurements of a set of high-quality short-period superlattices (SPS) GaAs/AlAs with 5-monolayer-thick AlAs barriers and variable width wells in the range of 4 to 10 monolayers are presented. Information on the lowest gap was obtained by PL measurements, and the PR, as we show in this study, contained the information about the lowest direct gap. Calculations based on a simple Kronig-Penney model in which X states in AlAs are confined by higher energy X states in GaAs concur with the experimental measurements obtained. Three new transitions associated with phonon replicas have been observed on the low-energy side of the main photoluminescence peak.