Photocurrent Spectroscopy of Excitonic Transitions in CdZnS/ZnS Strained-Layer Superlattices

We report the first observation of excitonic transitions in the photocurrent spectra (PCS) of MQW Cd x Zn1-x S/ZnS (x=0.25) strained-layer superlattices (SLS). In electric field dependent PCS measured at 14 K and at room temperature, we have observed a significant blueshift of the peak energy and photocurrent enhancement with increasing applied field. These results may be fully explained by assuming that this strained superlattice system exhibits a type II band lineup. Preliminary results for photo-detection in the ultraviolet are also presented and these suggest the possibility of producing a photo-modulator in the green to UV region of the spectrum.