Folded acoustic phonons in InAs-AlAs strained-layer superlattices
Raman spectroscopy is used to characterize highly mismatched (7%) InAs‐AlAs superlattices grown by atomic layer molecular beam epitaxy. In particular, folded acoustic modes are presented and compared with two different theoretical models (Rytov and linear chain). We find good agreement between theory and experiments. We estimate, with a simple model, the magnitude of the effect of the strain on the phonon frequency shifts.
Raman scattering study of folded acoustic phonons in GaAs/InxGa1−xAs strained‐layer superlattices
The excitation of zone‐folded longitudinal acoustic phonons in GaAs/InxGa1−xAs strained‐layer superlattices is observed by Raman scattering. The Raman data agree well with theory and are consistent with high indium concentrations achieved in the fabrication of these metastable superlattices of good crystalline quality.
Bulk and surface phonons in superlattices of diatomic crystals
Abstract The vibrations of a superlattice are studied within a model of diatomic linear chain crystals. For such an infinite or a semi-infinite superlattice the Green's function is calculated in explicit form. The dispersion of the bulk phonons are then obtained analytically, as well as the complex wavevector inside the gaps separating the bulk bands. Localized surface modes, decaying inside the superlattice, may exist in these gaps for a semi-infinite system. The model is applied to bulk and surface longitudinal phonons in GaAsAlAs superlattices.