Dislocation core structures in (0001) InGaN

Threading dislocation core structures in c-plane GaN and In_xGa_1−xN (0.057 ≤ x ≤ 0.20) films were investigated by aberration-corrected scanning transmission electron microscopy. a-type dislocations are unaffected by alloying with indium and have a 5/7-atom ring core structure in both GaN and In_xGa_1−xN. In contrast, the dissociation lengths of (a + c)-type dislocations are reduced, and new 7/4/9-atom ring and 7/4/8/5-atom ring core structures were observed for the dissociated (a + c)-type dislocations in In_xGa_1−xN, which is associated with the segregation of indium near (a + c)-type and c-type dislocation cores in In_xGa_1−xN, consistent with predictions from atomistic Monte Carlo simulations.