Gamma -X mixing in GaAs/AlxGa1-xAs coupled double quantum wells under hydrostatic pressure.

We have investigated the energies of the electronic states of GaAs/Al x Ga 1-x As strongly coupled double quantum wells and uncoupled multiple quantum wells as functions of hydrostatic pressure up to 35 kbar. The energies of the quantum-well states at 4 K were determined at each pressure by photoluminescence excitation spectra. The pressure coefficients of the energies of the allowed transitions between the valence-band and conduction-band quantized states of wide (200 A) uncoupled wells were all equal to the pressure coefficient of the bulk GaAs band gap