Codoped configuration effect on p-type doping efficiency in GaN

The ab initio ´mixed-basis + norm conserving non-local pseudopotential´ method ´was performed on calculating the electronic structures of four Mg-Si or Mg-O codoped configurations in wurtzite GaN. The results show that dense states generate around the valence band edges after codoping. The top of valance band split widely and shift up towards the conduction band in those codoped configurations, that the donor impurity (Si or O) is fixed in the site above the acceptor impurity (Mg). These electronic structure shifts can enhance the hole concentration about 103 times higher than that of Mg-doped GaN.