Periodic density functional studies on Mg(H) _x -doped GaN semiconductor

Periodic density functional calculations have been performed to study a mechanism of passivation of Mg-doped GaN by hydrogen. Optimizing different initial positions of hydrogen we found some favorable positions for the hydrogen atoms within the unit cells. We have found that the hydrogen atoms bind to the Mg in agreement with experimental findings and theoretical considerations. In addition the calculations revealed that the hydrogen atoms strongly interact with close nitrogen atoms. Our novel model of the simultaneous bond formation was supported by the charge distributions in the doped crystals.