FANO-LIKE RESONANT INTERFERENCE IN RAMAN-SPECTRA OF ELECTRONIC AND LO-VIBRONIC EXCITATIONS IN PERIODICALLY DELTA-DOPED GAAS

The asymmetry in the one-phonon Raman lines of a Si:GaAs delta-doped d oping superlattice is interpreted as a quantum-mechanical interference process in which an incident photon is inelastically scattered by a r esonance 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 t o the crystal axis of the incident and the inelastically scattered rad iation is produced by the difference in Raman-scattering amplitudes as sociated with each component of the mixed excitation.