Anomalous electrical response in ethanol-adsorbed zinc oxide thin films under visible light

In this paper we report a unique electrical response of ethanol-adsorbed ZnO films subjected to a constant potential difference. Current measurements were obtained in both dark and illuminated conditions. A significant delay in achieving saturation current was observed indicating a nonlinear and time varying effective resistance; a time-dependent equation describing this behavior was developed, allowing the calculation of a time constant for the transition regime. To determine the role of the surface properties in this behavior, microwave plasma was used to etch the ZnO film by varying degrees, resulting in an enhancement of the resistance switching for extended etching times.