CdS-CdSe and CdS-ZnSe intrinsic Stark superlattices

The first evidence of the intrinsic Stark effect at visible wavelengths (∼ 600 nm) is reported for a CdS-ZnSe strained layer superlattice (SLS) grown on a (111)A GaAs substrate. At the same time, smaller but significant exciton peak shifts with excitation power occur for similar samples that were grown on (100)GaAs substrates and thus predicted not to exhibit the effect. We attribute these shifts to band filling in a relaxed type-II SLS. We also report the largest light-induced exciton peak shift ever observed, 600 meV, in a CdS-CdSe piezoelectric type-II strained layer superlattice. A shift of 150 meV per decade of excitation power occurs in a superlattice of period 16 nm under both pulsed and CW excitation at low temperature. Finally we mention the prospect of producing optically activated modulators that work in the visible and near infrared spectral region (500-1100 nm) from such structures.