X-ray photoelectron spectroscopy study of Al- and N- co-doped p-type ZnO thin films

The chemical state of nitrogen, aluminum, oxygen and zinc in Al–N co-doped p-type ZnO thin films was investigated by X-ray photoelectron spectroscopy (XPS). N1s peak were detected in both the two p-type ZnO thin films, showing two components. The higher binding energy peak may be due to the Al–NO–H species, and the lower one perhaps derive from the (NH2)− cluster for the ammonia introduction. These two peaks both contribute to the p-type behavior in the ZnO films. A symmetry 74.4 eV binding energy in Al2p3/2 photoelectron peaks revealed an Al–N bonding state, a key factor to the co-doping method.