Micro-Raman phonon scattering by InAs/AlAs quantum dot superlattices

Raman scattering from the planar surface and the cleaved (110)-oriented edge of the nanostructures was investigated. Doublets of folded longitudinal acoustic (FLA) phonons up to 7th order were observed in the Raman spectra measured in the z(x,x)-z scattering geometry whose energy positions are well described by the elastic continuum model of Rytov. The in-plane Raman scattering spectra measured in the y′(x′,x′)-y′ geometry reveal the changing energy positions and intensities of the FLA doublet components which are consistent with the changing effective wave vector in the nanostructures induced by the momentum transfer of the light. The Raman selection rules for the FLA phonons with different symmetries are discussed.