Interface vibrational Raman lines in GaAs/AlxGa1−xAs superlattices

We report the observation of interface phonons in GaAs/${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As superlattices using Raman scattering. As predicted by the theory, all the three interface phonons, two in the region of GaAs-like optical phonons and one in the region of AlAs-like optical phonons, are observed. The Raman intensities associated with the interface phonons are enhanced when the incident photon energy is close to the exciton energy in the GaAs quantum wells. The dependence of the interface mode frequency on the incident photon energy is found to be one of the important factors in distinguishing the interface modes from the bulk optical phonons.