The lattice-misfit InN/GaN (00•1) interface supports a triangular network of α-core 90° partial misfit dislocations. These misfit dislocations provided excellent strain relief. However, in their unreconstructed form the dislocation contained numerous high-energy N dangling bonds, which must be eliminated by reconstructing the dislocation core. Existing single-period and double-period dislocation reconstruction models eliminated these dangling bonds via a like-atom dimerization, such as N-N dimers. However, it was shown that  these N-N dimers were unstable for the III-N materials, so an entirely new reconstruction mechanism was needed. A “triple-period” structural model was developed which eliminated N dangling bonds via the formation of N vacancies instead of N-N dimers. The model contained no N-N (or III-III) bonds, fully bonds all N atoms to four group-III neighbouring atoms, and satisfies the “electron counting rule” by transferring charge from In dangling bonds to Ga dangling bonds.

Triple-Period Partial Misfit Dislocations at the InN/GaN (0001) Interface: a New Dislocation Core Structure for III-N Materials. L.Zhang, W.E.McMahon, Y.Liu, Y.Cai, M.H.Xie, N.Wang, S.B.Zhang: Surface Science, 2012, 606[21-22], 1728-38