Electronic structure and optical properties of [(ZnSe)m(CdSe)n]N-ZnSe multiple quantum wells

The electronic energy bands of (ZnSe${)}_{\mathit{m}}$(CdSe${)}_{1}$ and (ZnSe${)}_{\mathit{m}\mathrm{\ensuremath{-}}1}$(${\mathrm{Cd}}_{0.5}$${\mathrm{Zn}}_{0.5}$Se${)}_{2}$ (m=2,3) superlattices are calculated with the empirical nonlocal pseudopotential method taking into account the strain effect. The energy gaps, effective masses along different directions, the splitting of heavy- and light-hole bands, and spin-orbit splitting, etc. are obtained. Assuming that the (ZnSe${)}_{2}$(CdSe${)}_{1}$ and (ZnSe${)}_{3}$(CdSe${)}_{1}$ superlattices in the corresponding [(ZnSe${)}_{\mathit{m}}$(CdSe${)}_{\mathit{n}}$${]}_{\mathit{N}}$-ZnSe (m=2 or 3, n=1) multiple quantum wells as a whole are one kind of potential-well materials, we calculated the quantum energy levels of the electron and the heavy hole, and the exciton binding energies as functions of period number N of the superlattice. The variations of energy gaps of the two superlattices with temperature are calculated. Taking into account the confined energy in the quantum well and the exciton binding energy, the energy positions of exciton peaks are compared with the luminescence experiments of the multiple quantum wells. The variations with temperature are in good agreement, and the discrepancies between the calculated results and the experimental data are suggested as being due to the interface alloy formation.