Phonon frequencies for Si-Ge strained-layer superlattices calculated in a three-dimensional model

We present the results of full three-dimensional calculations of phonon frequencies in silicon-germanium strained-layer superlattices (SLS’s) and compare with experimental data. We use a modified version of the six-parameter valence-force-potential model, incorporating the strained nature of the layers. We confirm that the dispersion relations for Si/Ge SLS’s fall into bands closely associated with the bulk dispersion relations of silicon and …