LATTICE VIBRATION IN ALTERNATING MONOLAYERS OF ZNSE AND ZNTE

Lattice vibration in alternating monolayers of ZnSe and ZnTe is studie d. Optical vibrational modes observed from (ZnSe)n-(ZnTe)n (n = 2, 3, 4) short-period superlattice are evaluated by a theoretical analysis u sing the linear-chain model. A method of the calculation which can tak e into account lattice strain is proposed. It is found that the zeroth - and the first-order folded phonons in the ZnSe layer are observed in Raman scattering. By investing the displacement of the atoms, it is a lso found that the ZnSe-like LO mode is localized in the ZnSe layer, w hereas no mode is localized in the ZnTe layer. This characterization i s attributed to an overlap of the dispersion curves for ZnSe- and ZnTe -LO modes in the strained layer.