Coexistence of unipolar and bipolar resistive switching characteristics in ZnO thin films

Abstract

This paper reports the coexistence of unipolar and bipolar resistive switching (BRS) in an Ag/ZnO/Pt structure fabricated by sputtering deposition at room temperature. The structure shows reproducible and stable unipolar resistive switching after electroforming with high compliance current (I-c) = 40 mA, regardless of the applied voltage polarity. With low I-c = 5 mA at electroforming, BRS was also observed; this phenomenon depended on the voltage polarity. Both states were stable and reproducible over 100 cycles. The switching mode was changed with adjusting Ic but the transition was irreversible. Based on the results, switching mechanism based on filament theory is proposed to explain both resistive switching. (C) 2010 American Institute of Physics. [doi:10.1063/1.3489882]