Localization and relaxation of excitons in CdZnS/ZnS strained-layer superlattices studied by photoluminescence excitation and photocurrent spectroscopies

Abstract

A multiple LO-phonon emission process related to the relaxation of excitons of Cd x Zn 1− x S/ZnS strained-layer superlattices ( x = 0.3), has been observed in the photoluminescence excitation spectra. The localization of excitons has been found to be the dominant cause of the linewidth broadening. In electric field dependent photocurrent spectra, a significant blueshift of the peak energy and photocurrent enhancement take place with increasing applied field. These results may be fully explained by assuming that this strained superlattice system exhibits a type II band lineup.