X-ray and Raman characterization of AlSb/GaSb strained layer superlattices and quasiperiodic fibonacci lattices.

Double crystal rocking curves of samples grown on (001) oriented GaSb substrates by molecular beam epitaxy have been analyzed by fitting computer simulations to data for the symmetric (004) and (002) reflections and for asymmetric (115) reflections. Rocking curves revealed a multiplicity of superlattice diffraction peaks. Dynamical diffraction theory using Abeles method was applied for the symmetrical reflections. We compare our results to standard kinematical simulations, and we find that there are significant differences. For the asymmetric reflections a new dynamical simulation code involving an 8 x 8 matrix solution of Maxwell's equations was used. Lattice incoherency was determined from measurements of the in-plane mismatch. Dramatic diffraction peak broadening was observed for incoherent superlattices, and this broadening was attributed to a mosaic structure formed by misfit dislocations. Peak broadening was used to infer both a growth direction as well as an in-plane coherence length.