Universal behavior of the electron g factor in GaAs/AlxGa1-xAs quantum wells

The Zeeman splitting and the underlying g factor for conduction-band electrons in GaAs/AlxGa1-xAs quantum wells have been measured by spin-beat spectroscopy based on a time-resolved Kerr rotation technique. The experimental data are plotted as functions of the lowest band-to-band optical transition energy, i.e., the effective band gap of the quantum wells. The model calculations suggest that in the tracked range of transition energies E from 1.52 to 2.0 eV, the component of electron g factor along the growth axis follows closely the universal dependence g(parallel to)(E)approximate to 0.445+3.38(E-1.519)-2.21(E-1.519)(2) (with E given in eV), and this universality also embraces AlxGa1-xAs alloys. On the other hand, the in-plane g factor component deviates in a systematic way from this universal curve, with the degree of deviation controlled by the structural anisotropy. The experimental data are in good agreement with the theoretical predictions.