First-Principles Calculations on Mg Impurity and Mg–H Complex in GaN

Abstract

First-principles calculations are performed in order to investigate the atomic geometry and stability of the Mg impurity and Mg–H complex in GaN. We find that a doped Mg atom is stable at a Ga substitutional site with only slight lattice relaxation, suggesting that the Mg impurity induces a shallow acceptor level. It is also found that this Mg impurity forms a very stable complex with an incorporated hydrogen; the hydrogen atom intervenes between the N and Mg atoms to form the stable Mg–H complex. The formation of this stable Mg–H complex is expected to be the reason for the experimental result that the acceptor is passivated by the hydrogen. Local vibrational frequencies of the Mg–H complexes are also discussed.