Magneto-optical study of quantum-well electronic structure using disorder-induced resonant acoustic-phonon Raman scattering

We study the electronic structure of a (100/103)-Å GaAs/${\mathrm{Al}}_{0.35}$${\mathrm{Ga}}_{0.65}$As multiple quantum-well sample using the resonant enhancement of disorder-induced continuous Raman emission by acoustic phonons at interband magneto-optical transitions between Landau levels. Calculations are compared to fan plots of excitation energy vs resonance magnetic field and material parameters are determined. We find a significant difference between the electron effective mass for confinement (${\mathit{m}}_{\mathit{e}}^{\mathrm{\perp }}$=0.068${\mathit{m}}_0$) and that which describes Landau quantization (${\mathit{m}}_{\mathit{e}}^{\mathrm{\parallel }}$=0.073${\mathit{m}}_0$). Both masses are enhanced as compared to the bulk value (${\mathit{m}}_{\mathit{e}}$=0.0665${\mathit{m}}_0$). Our results confirm theoretical predictions on the influence of conduction band nonparabolicity and anisotropy on effective masses in quantum wells.