Origin of p-Type Doping in Zinc Oxide Nanowires Induced by Phosphorus Doping: A First Principles Study

We investigated the geometric and electronic properties and doping efficiency of phosphorus-doped zinc oxide nanowires along the [0001] direction using the first-principle calculation. For isolated point defects, the substitutional and vacancy defects prefer the edge of the nanowire, the Zn interstitial defects favor the tetrahedral site, and the most stable P and O interstitial defects have a dumbbell-like structure. A complex defect of PZn−2VZn is formed by the combination of a substitutional P at a Zn site (PZn) and two Zn vacancies (VZn), and it prefers the edge site. We found that PZn defects could be effective donors while VZn and PZn−2VZn defects could be effective acceptors. The PZn defects have low formation energies and high concentrations under the Zn- and P-rich conditions, and they can lead to n-type ZnO nanowires. The VZn defects have low formation energies and high concentrations under the O- and P-rich conditions. The VZn defects can greatly suppress the PZn defects. VZn and PZn−2VZn defects can lead to p-type ZnO nanowires under the O- and P-rich conditions.