Phonon Folding in ZnSe–ZnTe Strained Layer Superlattices

Folding of longitudinal acoustic (LA) mode phonons in ZnSe–ZnTe strained layer superlattices, grown on the (001) GaAs without buffer layers by molecular beam epitaxy (MBE), was measured as a function of period and thickness of the layers by Raman scattenng. The dispersion relation between observed LA frequencies and wave number of the superlattices was analyzed by fitting the sound velocity as a parameter in the Rytov model. Two analytical solutions were obtained from the model. It is supported by consideration of calculation and experimental results that the sound velocity of the ZnSe and ZnTe layers in the superlattices is smaller and larger than their bulk values respectively, and this implies elongation of the ZnSe layers and compression of the ZnTe layers.