Fine structure of reflectance spectra due to exciton quantization in near-surface quantum wells based on ZnS_xSe_(1-x) ternary alloys

摘要

ZnS_xSe_(1-x) alloy films with and without near-surface quantum wells were deposited on the GaAs substrates in the photo-induced MOCVD growth process. The reflection spectra of the structures have been studied experimentally and theoretically. The spectra from the film containing a photo-induced near-surface quantum well show additional reflectance peaks as compared to the quantum well free film. The number and position of the additional peaks are governed by the lateral local composition x . A theoretical model explaining the principal exciton-mediated features of the experimental reflectivity spectra is developed. The resonant spectral structure of the reflectivity is shown to be due to the center-of mass quantization of both light- and heavy-hole excitons inside the quantum well and due to free excitons in the thick (barrier) part of the ZnS_xSe_(1-x) film.