Effect of different atmospheres on the electrical stabilization of NiO films

Sputtered nickel oxide (NiO) films have a wide range of applications including their use in transparent conductive anodes for organic light-emitting diodes (OLEDs) where stable electrical properties are essential. Unfortunately, NiO films show electrical aging phenomenon in air. In the present experiments, the phenomenon of aging was investigated in different atmospheres including H2, CO, O2, CO2, N2, and Ar together with varying the humidity. It was found that NiO films were relatively stable in Ar but very unstable in H2, CO and humid argon atmospheres. The aging rate increased rapidly as the humidity was increased from 2 to 20 relative humidity (RH) and became constant from 20 to 40 RH.