Strain relaxation in InGaN/GaN epilayers by formation of V-pit detects studied by SEM, XRD and numerical simulations

V-pit defects in InGaN/GaN were studied by numerical simulations of the strain field and X-ray diffraction (XRD) reciprocal space maps. The results were compared with XRD and scanning electron microscopy (SEM) experimental data collected from a series of samples grown by metal-organic vapor phase epitaxy. Analysis of the principal strains and their directions in the vicinity of V-pits explains the pseudomorphic position of the InGaN epilayer peak observed by X-ray diffraction reciprocal space mapping. The top part of the InGaN layer involving V-pits relieves the strain by elastic relaxation. Plastic relaxation by misfit dislocations is not observed. The creation of the V-pits appears to be a sufficient mechanism for strain relaxation in InGaN/GaN epilayers.

Automated summary

This study investigates V-pit defects in InGaN/GaN and finds that the formation of V-pits is a sufficient mechanism for strain relaxation, with no observed plastic relaxation caused by misfit dislocations in the epilayers.