First-principles techniques were used to investigate the interaction of H with Ga vacancies in the wurtzite phase. The results revealed that H could either compensate a vacancy, by donating an electron to a vacancy acceptor level, or passivate a vacancy by forming a H-vacancy complex. A Ga vacancy could bind to up to four H atoms, and the H removal energies were estimated as a function of the number of H atoms. The removal energies were found to depend strongly upon the Fermi level, and complexes which contained more than two H atoms were predicted to be unstable in n-type samples.

Interaction of Hydrogen with Gallium Vacancies in Wurtzite GaN. A.F.Wright: Journal of Applied Physics, 2001, 90[3], 1164-9