Interdiffusion, segregation, and dissolution in InAs/GaAs quantum dot superlattices

We have investigated the effects of in situ and ex situ post-growth thermal annealing on the organization of InAs/GaAs quantum dot superlattices, whic h consist of regular arrays of InAs islands embedded in GaAs. Using large-s cale and high resolution cross-sectional scanning tunneling microscopy, we have mapped out the spatial distributions of the island arrays and the posi tions of indium atoms located both vertically and laterally between the isl and arrays. Both in situ and ex situ annealing induce vertical and lateral dissolution of the islands, which in turn significantly affects the organiz ation of the island arrays. Annealing-induced variations in the positions o f the indium atoms between the island arrays have enabled us to directly me asure indium-gallium interdiffusion and indium segregation lengths. We disc uss the effects of residual strain on these processes, which are critical f or the design of novel devices based upon semiconductor nanostructures.