SPIN-FLIP RAMAN-SCATTERING IN GAAS/ALXGA1-XAS MULTIPLE QUANTUM-WELLS

Strong spin-flip-related Raman scattering (SFRS) from p-type Be-doped GaAs/AlxGa1-xAs 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 g parallel-to = + 2.3, g perpendicular-to congruent-to 0, and that of the localized exciton (g(h) - g(e)) parallel-to = + 1.5, (g(h) - g(e)) perpendicular-to congruent-to 0 for the narrowest wells measured (approximately 40 angstrom).