Linear-chain-model interpretation of Raman scattering from ZnSe/ZnTe superlattices and ${\mathrm{ZnSe}}_{\mathit{x}}$${\mathrm{Te}}_{1\mathrm{-}\mathit{x}}$ mixed crystals

We study the vibrational dynamics of strained-layer superlattices of ZnSe/ZnTe, using Raman spectroscopy together with calculations in a linear-chain model. Our analysis suggests (1) that the superlattices are free standing, i.e., separated elastically from their substrates, whether grown on GaAs or InP, and (2) that the degree of strain within the superlattice layers depends strongly on the superlattice period Λ. From essentially none at Λ=30 Å, the relaxation of the strain increases with Λ until full relaxation is encountered at Λ=90 Å. Additionally we discuss briefly the evidence for interfacial disorder in the superlattices and the single-mode spectra of ${\mathrm{ZnSe}}_{\mathit{x}}$ ${\mathrm{Te}}_{1\mathrm{-}\mathit{x}}$ mixed-crystal alloys.