Zn(S,Se)-based superlattices and quantum wells: Band offsets, excitons, linear and nonlinear optical properties

Wannier exciton properties in a superlattice (SL) of ${\mathrm{ZnS}}_{\mathit{x}}$${\mathrm{Se}}_{1\mathrm{-}\mathit{x}}$/ZnSe and in a single asymmetric quantum well of ${\mathrm{ZnS}}_{\mathit{x}}$${\mathrm{Se}}_{1\mathrm{-}\mathit{x}}$/ZnSe/ZnS strained materials are reproduced by an accurate variational envelope function. A systematic study of binding energy and oscillator strength is performed as a function of well and barrier thicknesses for alloy concentration x=0.18. Exciton energies are computed in SL’s and compared to available experimental data in the literature. Linear optical response and second-harmonic generation in asymmetric single quantum wells are also computed and briefly discussed.