Coexistence of the bipolar and unipolar resistive switching behaviors in vanadium doped ZnO films

• The coexistence of BRS and URS behaviors are observed in the V-doped ZnO film.
• The transition from URS to BRS is realized by controlling Icc and voltage range.
• Both BRS and URS modes possess good retention property and endurance.

The coexistence of bipolar and unipolar resistive switching (BRS and URS) modes are observed in the vanadium doped ZnO polycrystalline thin films fabricated by a sol–gel method. These two switching modes can be activated separately depending on the different compliance current (Icc) during the first voltage sweeping process: the fabricated device shows reproducible BRS behavior with a low compliance current Icc = 0.1 mA, while with a high Icc = 0.01 A, URS behavior was observed after electroforming. The conversion between BRS and URS is reversible. The conducting filament formation/rupture models with electrochemical redox reactions and thermal effects were suggested to explain the BRS and URS behaviors respectively.