Optics of multiple quantum wells uniaxially stressed along the growth axis

Data are presented on in-plane transmission of light and photoluminescence for GaAs/AlAs multiple quantum wells (MQW’s) uniaxially stressed along the z^=[001] growth axis. This stress leads to the simplest possible form of competition between confinement and stress in these microstructures. We show that by measuring the frequency-dependent birefringence in the energy window between the absorption edge of the MQW’s and that of the substrate (GaAs), direct information about the competition between uniaxial stress and confinement can be obtained. We find that the inclusion of finite k mixing between heavy- and light-hole bands is necessary in order to account for the otherwise very puzzling polarization rules of the luminescence. The piezobirefringence in the transparency region is found to be of the same order of magnitude than that of bulk GaAs. © 1996 The American Physical Society.