Resonance Raman Scattering by Confined LO and TO Phonons in GaAs-AlAs Superlattices

Abstract

It is shown that in GaAs-AlAs superlattices the confined longitudinal-optic Raman phonons created via either deformation-potential or Fr\"ohlich electron-phonon interaction are different. This effect is demonstrated by comparison of resonance and off-resonance Raman spectra. Phonons of ${A}_{1}$ symmetry (point group ${D}_{2d}$) dominate in resonance, while ${B}_{2}$ phonons are stronger in the off-resonance case. The resonance profile of the ${A}_{1}$ modes is discussed. We also report the observation of confined transverse-optic phonons under extremely resonant conditions.