Hydrogen Dissociation from Mg-doped GaN

We have investigated the thermal activation process of Mg dopant in Mg-doped GaN by secondary ion mass spectrometry (SIMS) and Hall measurement with the van der Pauw configuration. We have found a systematic relationship between the amount of the hydrogen dissociated from the Mg-doped GaN layer by thermal annealing and the electronic conductive properties of the layer, i.e., Hall mobility, Hall carrier density and resistivity of the layer. The hydrogen in the Mg-doped GaN layer has been classified into at least two different modes. The first mode involves relatively larger activation energy of the dissociation process from the Mg-doped GaN layer, and the dissociation energy from the Mg-doped GaN to the atmosphere is 0.8–1.5 eV. The second mode has the dissociation energy of 0.2–0.5 eV. The former mode may be associate with the hydrogen passivation of the Mg dopant in GaN and the latter one may be closely related to the passivation of the electrical compensation mechanism for the positive hole carriers in the Mg-doped GaN.