Exciton binding energy in (Al,Ga)As quantum wells: Effects of crystal orientation and envelope-function symmetry

We report the first observation of 2s-excitonic features in the luminescence of non-(001)-oriented (Al,Ga)As multiple-quantum-well structures and conclude that the heavy-hole excitonic binding energy does not depend significantly on the orientation of the quantum well in the crystalline lattice. This is substantiated by calculations showing only minor changes (0.3 meV) in the binding energy for the lowest heavy-hole exciton. However, a 10% anisotropy is predicted for the light-hole exciton, which is caused by mixing with the nearby second heavy-hole exciton.