Materials design for the fabrication of low-resistivity p-type GaN using a codoping method

On the basis of band-theoretical investigation using the augmented-spherical-wave (ASW) method, we propose a valence-control method, the ''codoping method'', to fabricate low-resistivity p-type GaN materials. p-type dopants lead to an increase in the electrostatic energy in GaN materials. This gives rise to destabilization of ionic charge distributions due to a shift, of N 2p levels towards higher energy regions. We clarified that codoping of n-type dopants, Si or O atoms, lead lo a stable p-type GaN:Mg atom material and investigated differences in the roles of Si-and O on the fabrication of low-resistivity p-type GaN materials.