Fano-like resonant interference in Raman spectra of electronic and LO-vibronic excitations in periodically δ-doped GaAs

The asymmetry in the one-phonon Raman lines of a Si:GaAs {δ}-doped doping superlattice is interpreted as a quantum-mechanical interference process in which an incident photon is inelastically scattered by a resonance excitation composed of a bulk LO one-phonon state mixed to a continuum of electron intersubband transitions. The dependence of the line shape on the frequency as well as on the polarizations relative to the crystal axis of the incident and the inelastically scattered radiation is produced by the difference in Raman-scattering amplitudes associated with each component of the mixed excitation.