Fine structure of reflectance spectra due to exciton quantization in near‐surface quantum wells based on ZnSxSe1−x ternary alloys

ZnSxSe1−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 ZnSxSe1−x film. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)