Spin-flip Raman scattering in GaAs/AlxGa1−xAs multiple quantum wells

Abstract

Strong spin-flip-related Raman scattering (SFRS) from p-type Be-doped GaAs/${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As multiple quantum wells (MQW’s), as well as from an undoped sample, has been observed. In both cases the SFRS exhibits a strong dependence on the geometry of the experiment. A theory is developed that explains SFRS in p-type MQW’s as related to a spin flip of a hole bound to an acceptor via exchange interaction with a neighboring exciton. SFRS in the undoped MQW’s is explained as a flip of the angular momentum of an exciton localized by interface roughness via interaction with acoustic phonons (doubly resonant scattering by acoustic phonons). The g tensor of the hole bound to the acceptor is determined to be ${\mathit{g}}_{\mathrm{\parallel }}$=+2.3, ${\mathit{g}}_{\mathrm{\perp }}$≃0, and that of the localized exciton (${\mathit{g}}_{\mathit{h}}$-${\mathit{g}}_{\mathit{e}}$ ${)}_{\mathrm{\parallel }}$=+1.5, (${\mathit{g}}_{\mathit{h}}$-${\mathit{g}}_{\mathit{e}}$ ${)}_{\mathrm{\perp }}$≃0 for the narrowest wells measured (∼40 Å).