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 $X_z$- and $X_x$,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 $X_z$ and $X_x$,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: $E_2$=5.1±0.7 eV.