Bipolar resistive switching characteristics of TaO₂ RRAM

The authors report the fabrication and characterization of a resistive random access memory (RRAM) with a Ti/TaO₂/Pt structure at room temperature. According to the X-ray photoelectron spectroscopy (XPS) analysis of the deposited TaO_x film and the data fitting of the XPS spectrum data, the deposited TaO_x film was then confirmed to be in the TaO₂ phase. The fabricated device was shown to exhibit bipolar resistance switching behavior over one hundred DC switching cycles and showed stable retention characteristics for over 10⁴ s under a 100 mV stress. It was also found that the electrical conduction mechanism in set process was firstly dominated by ohmic conduction and then transformed to the space-charge-limited process in the high resistance state. Finally, the conduction mechanism turned to ohmic conduction again in low resistance state.