Exciton states in GaAs/AlGaAs Bragg confining structures studied by resonant Raman scattering

Abstract

We report on the study of the low temperature resonant Raman scattering (RRS) in GaAs/Al 0.32 Ga 0.68 As Bragg confining structures (BCS). The LO-phonon RRS is observed in the spectral range of the (e B :hh B ) and (e B :lh B ) Bragg confined excitons. The RRS profiles show an outgoing beam resonance that is much stronger than the incoming beam resonance. These profiles are analyzed by a model in which the exciton dimensionality affects the in-plane exatonic dispersion and the Frohlich interaction dependence on the phonon wavevector. The exciton scattering, in its translational motion, is assumed to be due to heavy point defects (short range potential fluctuations). Detailed calculations of the RRS profiles result in excellent agreement with the observed spectra. From them we conclude that the Bragg confined (e B :hh B ) exciton is approximately 2-dimensional