RAMAN-STUDY OF FANO-LIKE ELECTRON-PHONON COUPLING IN DELTA-DOPING GAAS SUPERLATTICES

The interaction between electron excitations and LO phonons was studie d by Raman scattering in delta-doping GaAs superlattices. The off-reso nant spectra, to which the deformation potential contributes, reveal t he coupling of the LO phonons with the superlattice plasmon; however, those measured close to the E(0)+Delta(0) resonance of GaAs present bo th the Fano-like coupling of the LO phonons with the quasicontinuum si ngle-particle electron excitations and the coupling of the LO phonons with macroscopic depolarization fields of the intersubband electron ex citations. It was shown that the Frohlich interaction is responsible f or the Fano-type electron-LO-phonon coupling. Due to the self-consiste nt origin of the electron-energy spectrum in delta-doping superlattice s, the resonance of the Fano interference was found to be strongly dep endent on the electron density as well as on the excitation energy.