Band structure of ZnSe-ZnTe superlattices.

Abstract

We report the first study of the band structure of ZnSe-ZnTe superlattices. Our calculations are based on second order k\ensuremath{\cdot}p theory and include the effects of strain and spin-orbit splitting on the superlattice band structure. Since the valence-band offset for this system is not well known, we have investigated the dependence of the superlattice band gap on the valence-band offset. Based on the assumption that the photoluminescence from the superlattice is due to an isoelectronic ${\mathrm{Te}}_{1}$-bound exciton in ZnSe, we have fitted the experimental photoluminescence data with k\ensuremath{\cdot}p theory to obtain the best value of the valence-band offset. The value we find is 0.975\ifmmode\pm\else\textpm\fi{}0.098 eV. Alternatively, assuming that the photoluminescence is due to band-to-band transitions we obtain a valence-band offset of 1.196\ifmmode\pm\else\textpm\fi{}0.134 eV. We have also calculated the superlattice band gap as a function of the constituent-material-layer thicknesses for the first valence-band offset quoted. We expect these results to be important in gaining an understanding of the value of the band offset, and the nature of the photoluminescence from this system.