Electronic properties of (ZnSe)m(Cd1-xZnxSe)n superlattices.

Abstract

We present theoretical calculations on the electronic structures of (ZnSe${)}_{\mathit{m}}$(${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$Se${)}_{\mathit{n}}$ superlattices. First-principle pseudopotential calculations are performed to obtain the valence-band offset for CdSe grown on ZnSe. We then use an empirical nonlocal pseudopotential method, including the spin-orbit interaction to calculate the band structures and effective masses of (ZnSe${)}_{\mathit{m}}$(${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$Se${)}_{\mathit{n}}$ superlattices grown on ZnSe. The empirical pseudopotentials are taken to be linear combinations of Gaussian functions with a few adjustable parameters. The parameters of ZnSe and CdSe are fitted to available experimental data. The effects of strain due to lattice mismatch have been properly taken into account. We have also studied the band gap as a function of composition and layer thicknesses of constituent materials in superlattices. The results are in agreement with recent experimental data.