Using hybrid functional calculations, a study was made of the diffusion and thermal stability of H in Mg-doped GaN. Compared with the generalized gradient approximation, a higher activation barrier was obtained for dissociating a Mg-H complex. This was attributed to an increase in the binding energy of Mg-H. Kinetic Monte Carlo simulations yielded an annealing temperature of around 800C for activating Mg acceptors. This was close to measured values. The results provided an insight into the fact that the annealing temperature generally increased with Mg-H concentration, and that the re-trapping of H was partly responsible for the low doping efficiencies at high Mg concentrations.

Diffusion and Stability of Hydrogen in Mg-Doped GaN: a Density Functional Study. J.S.Park, K.J.Chang: Applied Physics Express, 2012, 5[6], 065601