Excitonic spectrum of [111] GaAs/GaxAl1−xAs quantum wells

We have studied the magneto-optical properties of GaAs/${\mathrm{Ga}}_{\mathit{x}}$ ${\mathrm{Al}}_{1\mathrm{-}\mathit{x}}$As quantum wells grown along the [111] crystallographic direction. The excitonic spectrum has been obtained by means of photoluminescence excitation measurements in the presence of an external magnetic field. From the analysis of the data we extract the binding energies and the excitonic reduced effective masses as a function of well width. A study of the polarization of the emission, exciting with circularly polarized light, yields information about the spin relaxation and its dependence on magnetic-field strength. The results are compared with available calculations and with those obtained in samples grown along the [001] direction.