Far Infrared Spectroscopy of Confined LO Phonons in [113] GaAs/AlAs Superlattices

Abstract

We report on the observation of both, GaAs and AlAs confined longitudinal optical (LO) phonons in Fourier transform infrared (FTIR) reflection measurements of [113] GaAs/AlAs superlattices. This observation is possible due to the use of samples grown on doped substrates in combination with the technique of oblique beam incidence. The phonon dispersions determined from the energies of the confined LO 1 and LO 3 modes in the GaAs and AlAs layers are in good agreement with theoretical predictions if the influence of interface roughness is accounted for.