Influence of intrinsic or extrinsic doping on lattice locations of carbon in semi-insulating GaN

We demonstrate that different doping approaches can significantly influence the lattice locations of carbon (C) in GaN grown by MOCVD. For intrinsically doped GaN with TMGa as the C source, an annealing induced switching process of C atoms from Ga sites to N sites is observed, revealing the existence of substitutional C atoms on both Ga and N sites. While for extrinsically doped GaN with propane as the C precursor, C atoms incorporate almost on N sites. From the viewpoint of growth dynamics, we propose a mechanism for C incorporation into different lattice locations.