Biaxial splitting of optical phonon modes in ZnSe-ZnS strained-layer superlattices

Abstract
Raman scattering studies were performed on ZnSe-ZnS strained-layer superlattices with the incident light parallel as well as perpendicular to the interface plane. We found for the first time that the optical phonon modes split into two types, that is a singlet and a doublet, by the built-in biaxial stress. A new method to characterize the directional stress is demonstrated.