Interfaces, confinement, and resonant Raman scattering in Ge/Si quantum wells

We address the question of confinement of the Ge-Ge mode in five-monolayer-Ge single and multiple quantum wells. Using Raman scattering, our data show strong dependence of the interface quality on the number of quantum wells and thereby on the confinement of both the phonons and the electronic states in the Ge wells. The dependence of line shape and peak position of the Ge-Ge Raman line with laser photon energy gives a clear indication of the existence of terraces in the interfaces of the Ge/Si multiple quantum wells.