The time dependence of electrical current of Ar ion-etched ZnO

The time dependence of electrical current of Ar ion-etched ZnO is studied. It is found that Ar ion etching is beneficial for introducing vacancy defects such as the oxygen vacancy and zinc vacancy. At a high enough electrical bias voltage, there is an abrupt increase in electrical current with increasing bias voltage time, indicating the growth and formation of a conducting filament. The light illumination has proved to be helpful for filament formation and growth. A quantified relation between the electrical current and time is obtained. The filament growth mechanism can be ascribed to nucleation and growth of a new phase, which is determined by the Johnson-Mehl-Avrami equation.