CTR and DCXRD studies of lateral ordering of quantum dots in multilayer periodic structures

Containing an array of vertically coupled InAs quantum dots (QDs) in GaAs m atrix, multilayer periodic InAs-GaAs structures grown by molecular beam epi taxy, were investigated by SR-CTR (synchrotron radiation-crystal truncation rods) and double-crystal X-ray diffraction (DCXRD). X-ray diffraction is v ery sensitive to the formation of vertically coupled QDs array, which chang es spatial distribution of the scattered radiation. The appreciable elongat ion of superstructural and substrate spots in lateral directions is explain ed by occurrence of an additional long-range lateral ordering of scattering objects and quasi-periodic deformation relief in the top GaAs layer. Perfe ct coherently-connected InAs and GaAs clusters are introduced as a novel qu alitative structural model of scattering layers. Based on this model the ma in features of spatial distribution of diffracted intensity have been expla ined.