Onset of plastic relaxation in semipolar (112bar2) InxGa1-xN/GaN heterostructures

The onset of plastic relaxation via misfit dislocation (MD) formation in In_xGa_1-xN layers grown by metal-organic chemical vapor deposition on the (112bar2) 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_xGa_1-xN 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 {11bar00}-typem-planes, which eventually leads to an increase in threading dislocation density.