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-resistivityp-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 2plevels towards higher energy regions. We clarified that codoping ofn-type dopants, Si or O atoms, lead to a stablep-type GaN:Mg atom material and investigated differences in the roles of Si and O on the fabrication of low-resistivityp-type GaN materials.