V-pit defekty v InGaN/GaN studované rentgenovou difrakcí

Stránská Matějová, Jana

V-pit defects in InGaN/GaN heterostructures were studied by high-resolution x-ray diffraction accompanied by numerical simulations. The work is focused on the role of the V-pits in strain relaxation, on their impact on the appearance of the x-ray reciprocal- space maps and on their relation to the threading dislocations. Analysis of the diffuse part of the diffracted intensity by kinematical scattering theory, together with principal strains and their directions in the vicinity of the V-pit, explains why the lateral position of the InGaN peak is not affected by the V-pits presence. The strain relaxation by V-pit formation was confirmed, while plastic relaxation by misfit dislocations was not observed. The density of the V-pits in the epilayer turned out to be given by the content of threading dislocation with a screw component in the substrate. Pure edge threading dislocations do not affect the V-pit density. The In concentration has an influence on the size of the V-pits, but not their density. 1

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