Triple-Period Partial Misfit Dislocations at the InN/GaN (0001) Interface: A New Dislocation Core Structure for III-N Materials

The lattice-misfit InN/GaN (0001) interface supports a triangular network of α-core 90° partial misfit dislocations. These misfit dislocations provide excellent strain relief. However, in their unreconstructed form the dislocation contains numerous high-energy N dangling bonds, which must be eliminated by reconstructing the dislocation core. Existing single-period (SP) and double-period (DP) dislocation reconstruction models eliminate these dangling bonds via a like-atom dimerization, such as N-N dimers. However, we show that these N-N dimers are unstable for the III-N materials, so an entirely new reconstruction mechanism is needed. A "triple-period" (TP) structural model is developed which eliminates N dangling bonds via the formation of N vacancies instead of N-N dimers. The model contains no N-N (or III-III) bonds, fully bonds all N atoms to four group-III neighboring atoms, and satisfies the "electron counting rule" by transferring charge from In dangling bonds to Ga dangling bonds.