It was found that, in the absence of threading dislocations in InxGa1-xN/GaN heterostructures, coherent generation of misfit dislocations occurred for x > 0.11 in 100nm-thick epilayers. The present work focussed on In0.17Ga0.83N grown onto a low defect-density GaN free-standing substrate (with 1.9% lattice mismatch). A diffraction contrast analysis carried out in a transmission electron microscope revealed straight line defects with Burgers vectors of 2/3<11▪0> (that is, 2a; where a was the hexagonal plane lattice parameter), which extended by many μm along approximately <1¯1▪0> directions; with an average lateral spacing of 90nm. Although these defects were complex and mostly sessile, evidence was found that they could dissociate into glissile misfit dislocations with Burgers vectors of 1/3<11▪0>. It was proposed that the defects were generated by a punch-out mechanism involving slip on inclined prismatic planes. The properties of these defects and their role in relieving misfit strains were considered.

Misfit Dislocation Generation in InGaN Epilayers on Free-Standing GaN. R.Liu, J.Mei, S.Srinivasan, H.Omiya, F.A.Ponce, D.Cherns, Y.Narukawa, T.Mukai: Japanese Journal of Applied Physics, 2006, 45[22], L549-51