Electric field effects in ZnSerBeTe superlattices

Field-dependent optical properties of wide band gap type II ZnSerBeTe superlattices SLs. are investigated by photoluminescence and electroreflectance. For a 40-A° period SL, lattice matched to GaAs, the lowest spatially indirect transition is found in the visible spectral range at 2.04 eV at room temperature. By application of external voltages, Uext shifts of the transition up to 65 meV are demonstrated. The series of electroreflectance spectra for different Uext shows spatially indirect as well as direct transitions. An optical layer stack model allows a quantitative description. Furthermore, electric field-dependent resonant Raman spectroscopy of confined optical phonons is applied to investigate the shape of a tunneling hole wave function in ZnSe. The shape is found to be very sensitive to applied electric fields. q2000 Elsevier Science B.V. All rights reserved.