Characterization of the spatial inhomogeneity of heterointerfaces in GaAs/AlGaAs quantum wells by photoreflectance spectroscopy

GaAs/AlGaAs quantum-well heterostructures with well widths from 20 to 35 nm are investigated by photoreflectance spectroscopy. The broadening of spectral lines related to band-to-band transitions increases with the transition energy and decreases with the well width. The observed decrease in the broadening parameter with increasing well width is explained in terms of spatial inhomogeneity of the heterointerfaces. According to the experimental data, the interface inhomogeneity in the structures under study is 0.34–0.39 nm (1.3–1.4 monolayers).