N interstitial and its interaction with substitutional Mg in p -type GaN

Abstract

Density-functional theory and the generalized gradient approximation were utilized to investigate the local-energy-minimum configurations and formation energies of N interstitials and their interaction with substitutional Mg in p -type GaN. Along with previously proposed configurations of the N interstitial, a new variant of the split interstitial is discussed. Split interstitials are more stable than the other configurations of the interstitial. The formation energies are such that N interstitials are not expected to form under equilibrium conditions, however, they may form during nonequilibrium processes and become mobile during annealing. The N interstitial is found to bind with substitutional Mg, with the binding energy of the complex being 0.75, 0.53, and 0.35 eV for the +2, +1, and neutral charge states of the complex. © 2005 American Institute of Physics.