Raman scattering from CdSe/ZnSe self-assembled quantum dot structures

We report Raman scattering from CdSe/ZnSe self-assembled quantum dot structures. A series of samples, each with a different growth-interruption time before ZnSe caping of the CdSe dots, is investigated. ZnSe longitudinal optical (LO) phonon shifts as a function of the interruption time show a complex pattern due to the evolution of CdSe dots. We observe an LO phonon from the CdSe dots at $\sim 221{\mathrm{cm}}^{-1}$ as well as an interface phonon at $\sim 245{\mathrm{cm}}^{-1}.$ We present evidence that the interface phonon is localized at the interface between the CdSe dots and the ZnSe cap layer.