X-ray transmission topography of GaAs/InGaAs strained layer superlattices

Abstract X-ray transmission topographs of GaAs/In 0.15 Ga 0.85 As strained layer superlattices are presented. Superlattices composed of 4-period are shown to be free of misfit dislocations and if composed of 10 periods they exhibit some misfit dislocations. The topographs of specimens prepared to have a very low angle chemically realized bevel show that the misfit dislocations are located at the first interface between the substrate and the superlattice, and that the amount of relaxation is about 4% in the case of a 10-period superlattice.