Solution Using a Codoping Method to Unipolarity for the Fabrication of p-Type ZnO

We have investigated the electronic structures of n - or p -type doped ZnO based on ab initio electronic band structure calculations. We find unipolarity in ZnO; n -type doping using Al, Ga or In species decreases the Madelung energy while p -type doping using N species increases the Madelung energy, in addition to causing substantial localization of the N states. Codoping using reactive codopants, Al, Ga or In, enhances the incorporation of N acceptors in p -type codoped ZnO. We find the delocalized states of N for p -type ZnO codoped with N and Al (Ga).