Indirect, quasi-direct, and direct optical transitions in the pseudomorphic 4X4 monolayer Si/Ge strained layer superlattice on Si(001).

Estimates are presented for the lower lying optical transitions in the pseudomorphic 4X4 monolayer Si/Ge strained layer superlattice on Si(001). Band lineups incorporate a full self-consistent treatment of the 4X4 supercell. Confinement energies are obtained using a modified Kroenig-Penny model. We find that the lower lying q=0 superlattice transitions tend to cluster into three groups having energy centroids near 0.8, 1.2, and 2.2eV; in reasonable agreement with recent electroreflectance measurements on these structures.