Quantitative structural characterization of annealed InAs/GaSb superlattices*

MBE grown InAs/GaSb superlattices without \textit{in situ} thermal processing were post-growth annealed in vacuum and analyzed by a combination of XRD and structural refinement. The refinement shows a FWHM of satellite peak broadening and a d-spacing contraction in InAs constituent layers, which are caused by interfacial roughness and inhomogeneous strain, when the annealing temperature is above 200 $^{o}$C. Furthermore, the annealing above 450 $^{o}$C destroys the superlattice structure and annihilates all satellite peaks. An additional series of satellite peaks showing InSb-like behavior was found in annealed superlattices which is reduced by further annealing at 200 $^{o}$C. The refinement reveals that these peaks arise from the ``superlattice'' composed of InSb-like structure. The surface morphology studied using AFM shows that the InAs/GaSb superlattice surfaces evolve from flat plane, porous structure, and pebble structure to island structure as the annealing temperature increases.