Strain Accommodation in GaSb/AlSb Superlattices on (001) GaSb Substrates with AlSb Buffers

We report the observation that AlSb layers thinner than the epilayer critical thickness for the onset of plastic relaxation undergo lattice relaxation when used as buffers for GaSb/AlSb superlattices on (001) GaSb substrates. It is found that this is induced by the external stress from the overlaying superlattice, and that the mechanism is consistent with relaxation processes involving the nucleation and expansion of half-loops earlier suggested for strained epilayers. Photoluminescence spectroscopy conforms with the in-plane strains calculated from double-crystal and small-angle X-ray diffraction measurements.