Density-functional theory and the generalized gradient approximation were utilized to investigate the interaction of N interstitials with neutral MgH centers in p-type GaN. Formation energies and the corresponding local-energy minimum configurations of the defect complex were reported along with the energy to dissociate the complex into isolated MgH and a N interstitial. The conclusion was that N interstitials will bind with MgH centers in p-type GaN(Mg,H), with binding energies of 0.71, 0.44 and 0.29eV in the +3, +2, and +1 charge states, respectively. Hydrogen local-mode vibrational frequencies for the bound complex were estimated and compared to previous results for isolated MgH. The binding of a N interstitial to MgH perturbed the H stretch-mode frequency by 25/cm. These results were explained in the context of experiments which suggested that N interstitials, created by proton irradiation, became mobile during subsequent annealing and bonded with MgH centers in p-type GaN(Mg,H).

Binding of the N Interstitial with Neutral MgH in p-Type GaN Investigated with Density Functional Theory. R.R.Wixom, A.F.Wright: Physical Review B, 2005, 72[2], 024114