AZO work function enhanced by oxygen plasma immersion ion implantation

The surface of aluminum-doped ZnO (AZO) films was modified using the oxygen plasma immersion ion implantation method, which is also called O-PIII. The modified AZO films were analyzed by an X-ray photoelectron spectroscopy system (XPS), X-ray diffraction (XRD), a UV–visible spectrophotometer, atomic force microscopy (AFM), and a Kelvin probe instrument (KP). The results showed that O-PIII modification can further enhance the work function (WF) of AZO based on oxygen plasma (O-ICP) treatment. The optical characteristics of AZO thin films are nearly entirely preserved, and the surface morphology is enhanced. The variation in WF was strongly linked to the surface stoichiometry. The reduction of oxygen vacancies should be attributed to the high WF. The WF of the modified AZO films decreased rapidly with exposure time in the air promptly following O-ICP and O-PIII modification. Nonetheless, the O-PIII treatment had a longer-lasting effect. •The method called oxygen plasma immersion ion implantation (O-PIII) was introduced to modify the surface of AZO thin films.•The surface work function of AZO can be further enhanced by O-PIII treatment based on O-ICP treatment.•The work function of AZO treated by O-PIII increased by 1.1eV, a further improvement of 0.5 eV compared with O-ICP.•It was suspected that the elimination of oxygen vacancies on the AZO surface was responsible for the high work function.•The AZO films modified by O-PIII were more stable than those processed by the O-ICP treatment.