On the atomic structure of periodic [0 0 0 1] tilt boundaries in GaN: dislocation mobility and boundary-dislocation interaction

We have investigated the mobility of the crystal dislocations and their interaction with certain tilt boundaries in GaN by means of atomic computer simulation. Among the three possible stable cores of the 1/3 [2,1̄,1̄,0] (a-type) edge prism dislocation, namely, C5/7, C4 and C8, it was found that the C4 and C8 cores move under an applied strain whereas the C5/7 core is sessile. The a edge basal, a screw and c dislocations are not mobile under strains up to 5%. The simulation also shows that a C4 or C8 units at the interface of certain tilt boundaries move under an applied strain. In turn, dislocations can either annihilate or incorporate on these boundaries.