Modeling photoreflectance of quantum well heterostructures: A comprehensive approach

We present a comprehensive approach to modeling the photoreflectance (PR) spectra of semiconductor quantum wells embedded in layered heterostructures. Near-gap PR spectra are obtained directly from the calculated variation of surface reflectance spectra induced by modulation of an internal electric field. The field-dependent reflectance spectra are themselves obtained from a transfer matrix model of a quantum well heterostructure (QWH) in which the quantum well layer is treated in detail using electric-field-dependent optical absorption calculations and all surrounding higher-gap layers are treated as lossless dielectric slabs. The model is described in detail and is applied to unstrained GaAs/AlGaAs and compressively strained InGaAs/GaAs single-well QWHs for which both experimental data and other calculations are available for comparison. This model can serve as a tool for interpretation of experimental PR spectra, and should be particularly useful for analysis of dense spectra with overlapping features that would be difficult to analyze using empirical fitting schemes. The approach can be used to model electroreflectance without modification.