Weak-beam dark-field electron tomography of dislocations in GaN

By combining weak-beam dark-field imaging with tomography, we have been able to reconstruct the three-dimensional structure of dislocation arrays in GaN. With a mixture of both threading and in-plane dislocations, owing to plastic relaxation of the film, we look at how well each dislocation is reconstructed and what limits are imposed by way of dislocation density and material anisotropy.