Influence of hydrogen impurities on p-type resistivity in Mg-doped GaN films

The effects of hydrogen impurities on p-type resistivity in Mg-doped GaN films were investigated. It was found that hydrogen impurities may have the dual role of passivating Mg-Ga acceptors and passivating donor defects. A decrease in p-type resistivity when O-2 is introduced during the postannealing process is attributed to the fact that annealing in an O-2-containing environment can enhance the dissociation of Mg-Ga-H complexes as well as the outdiffusion of H atoms from p-GaN films. However, low H concentrations are not necessarily beneficial in Mg-doped GaN films, as H atoms may also be bound at donor species and passivate them, leading to the positive effect of reduced compensation. (C) 2014 American Vacuum Society.