Piezospectroscopy of GaAs-AlAs superlattices

Abstract

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\ifmmode\pm\else\textpm\fi{}0.7 eV.