SUPERLATTICE EFFECTS ON PHONONS IN STRAINED ZNTE-ZNSE STRUCTURES

Raman measurements are used to probe the built-in strain due to the la rge lattice mismatch in two short-period ZnSe-ZnTe superlattices. In t he largest period structure, local information on confinement and stra in effects in the different layers is deduced from the LO phonon frequ encies. An estimate of the in-plane strain gives evidence of a partial relaxation of both layers; in this structure, folded acoustical phono ns are clearly observed under resonant conditions. The Raman spectra o f the shortest period superlattice are characterized by a unique struc ture assigned to an unusual propagative mode resulting from the overla p of the optical bands of the two constituents.