Interface-induced localization of phonons in BeSe/ZnSe superlattices

The impact of interfacial transition layer thickness Delta is methodically investigated in the (BeSe)(10-Delta)/(Be0.5Zn0.5Se)(Delta)/(ZnSe)(10-Delta)/(Be0.5Zn0.5Se)(Delta) superlattices (SLs) for comprehending their phonon dispersions, Raman intensity profiles, and atomic displacements. By varying Delta from one to three monolayers, we have noticed a dramatic increase in the Raman intensity peaks with slight upward shifts of ZnSe-related optical phonons. An insignificant change is perceived, however, in the Raman features with remarkable downward shifts of the BeSe-type confined optical modes. These effects are ascribed to the localization of atomic displacements at the interfacial regions. The variations in phonon frequencies and enhancement of Raman line shapes can be used as vital tools for establishing the interfacial structures in SLs of technological importance.