Onset of plastic relaxation in semipolar (112¯2) In Ga1−N/GaN heterostructures

The onset of plastic relaxation via misfit dislocation (MD) formation in In x Ga 1− x N layers grown by metal-organic chemical vapor deposition on the ( 11 2 ¯ 2 ) semipolar plane of GaN substrates is investigated using high-resolution X-ray diffraction, transmission electron microscopy and cathodoluminescence. The results of critical thickness calculations for MD formation as a function of In x Ga 1− x N alloy composition x are compared with experimental observations. MD generation is observed initially as a result of slip on the (0001) slip plane, and subsequently as a result of additional slip on inclined { 1 1 ¯ 00 } - type m -planes, which eventually leads to an increase in threading dislocation density.