The interaction between electron excitations and LO phonons was studied by Raman scattering in δ-doping GaAs superlattices. The off-resonant spectra, to which the deformation potential contributes, reveal the coupling of the LO phonons with the superlattice plasmon; however, those measured close to the ${\mathit{E}}_0$+${\mathrm{\Delta }}_0$ resonance of GaAs present both the Fano-like coupling of the LO phonons with the quasicontinuum single-particle electron excitations and the coupling of the LO phonons with macroscopic depolarization fields of the intersubband electron excitations. It was shown that the Fröhlich interaction is responsible for the Fano-type electron–LO-phonon coupling. Due to the self-consistent origin of the electron-energy spectrum in δ-doping superlattices, the resonance of the Fano interference was found to be strongly dependent on the electron density as well as on the excitation energy. © 1996 The American Physical Society.

• Received 25 March 1996

DOI:https://doi.org/10.1103/PhysRevB.54.13927