Impact of air exposure on the chemical and electronic structure of ZnO:Zn3N2 thin films

The chemical and electronic surface structure of ZnO:Zn3N2 (ZnO:N) thin films with different N contents was investigated by soft x-ray emission spectroscopy. Upon exposure to ambient air (in contrast to storage in vacuum), the chemical and electronic surface structure of the ZnO:N films changes substantially. In particular, we find that the Zn3N2∕(Zn3N2+ZnO) ratio decreases with exposure time and that this change depends on the initial N content. We suggest a degradation mechanism based on the reaction of the Zn3N2 content with atmospheric humidity.