MASS TRANSPORT OF GaN AND REDUCTION OF THREADING DISLOCATIONS

Mass transport of patterned GaN at around 1100°C in nitrogen with an ammonia atmosphere has been discovered for the first time. The mass transport process is found to be affected by the anisotropy of surface energy of GaN. Behaviors of threading dislocations which are predominantly of the mixed type and the pure edge type are affected by the anisotropy during mass transport. Mixed type dislocations are bent keeping the geometrical relationship normal to the surfaces, while pure edge type dislocations are bent horizontally. This new-found process, the so-called "mass transport epitaxy," is one of the best methods for achieving low dislocation density GaN on the highly lattice-mismatched substrate.