An alternative approach to investigate the origin of p-type conductivity in arsenic doped ZnO

• Single crystalline ZnO films were grown onto semi-insulating GaAs substrate by MOCVD.
• Directional thermal diffusion of As from GaAs gave rise p-type conductivity in ZnO.
• DFT calculations revealed p-type nature along with ferromagnetism by AsZn–2VZn state.
• Magnetic measurements established ferromagnetism nature of the films after As doping.
• X-ray photoelectron spectra indicated the presence of AsZn–2VZn acceptor states.

P-type conductivity in MOCVD grown ZnO was obtained by directional thermal diffusion of arsenic from semi-insulating GaAs substrate. The films were single crystalline in nature and oriented along (002) direction. Ab initio calculations in the framework of density functional theory have been carried out with different chemical states of arsenic in ZnO. Present calculations suggested AsZn–2VZn defect is a shallow acceptor and results in ferromagnetism in ZnO. The magnetic measurements of the samples indeed showed ferromagnetic ordering at room temperature. X-ray photoelectron spectra confirmed the presence of AsZn and VZn. The core level chemical shift in binding energy of AsZn indicated the formation of AsZn–2VZn. Diffused arsenic substitutes zinc atom and creates additional zinc vacancies. The zinc vacancies, surrounding the oxygen atoms, result in unpaired O 2p electrons which in turn induce ferromagnetism in the samples.