Nonvolatile Unipolar and Bipolar Resistive Switching Characteristics in Co-doped TiO2 Thin Films with Different Compliance Currents

The resistive switching behavior of 100nmthick Co-doped TiO2 thin films grown by using a conventional rf magnetron sputtering system was investigated by using structural and electrical measurements The Co-doped TiO2 thin films dispaly a rutile phase and a column-like structure. An unusual result, a switching transition from a unipolar to a bipolar behavior, was clearly observed at a high compliance current. The experimental results suggest that the switching transition is related to the formation of trap sites (CoOx, TiO2-x, and Co-x-Ti1-xO2) under large electrical stress conditions. The improved reproducible switching properties of our Co-doped TiO2 materials under forward and reverse bias stresses demonstrate the possibility of future non-volatile memory elements.