Al electrode dependent transition to bipolar resistive switching characteristics in pure TiO2 films

Abstract

Stable bipolar resistive switching was demonstrated in polycrystalline TiO2 films involving two different top and bottom Al electrodes of two different structures (Al/TiO2/Pt and Pt/TiO2/Al) after a forming process. With an Al electrode, the transition to bipolar resistive switching was clearly observed, together with counterclockwise and clockwise switching directions, which depended on the position of the Al electrode. The transition from unipolar to bipolar resistive switching seems to be attributable to the redox reaction and trap/detrap at the interfaces between the Al electrode and TiO2 layer due to the migration of oxygen ions and electrons. However, current level analysis of devices reveals that the forming process method basically leads to the formation of conducting paths inside the TiO2 layers. The electrical device properties of the two different structures, the effects of compliance currents, and the operation voltages are also analyzed.