Piezospectroscopy of GaAs-AlAs superlattices

Piezospectroscopic studies of type-I and type-II GaAs-AlAs superlattices have been made for stress lying along the plane or along the growth axis. Ground and excited states have been studied by means of reflectivity for type-I superlattices. In type-II superlattices the X symmetry of the conduction subband has been observed. A reversal of the ordering of the Xz- and Xₓ,y-type conduction subband has been found to appear when the thickness of the AlAs slab is changed. This was interpreted as a contribution of the internal strain experienced by the AlAs slabs lattice matched to the GaAs substrate. Stress-induced switching of ordering between Xz and Xₓ,y conduction states was observed in the case of stress perpendicular to the growth axis of the superlattice. We deduce the tetragonal shear deformation potential of AlAs conduction band: E₂=5.1±{}0.7 eV.