Low-Power Resistive Switching Characteristic in HfO₂/TiO_x Bi-Layer Resistive Random-Access Memory

Resistive random-access memory devices with atomic layer deposition HfO₂ and radio frequency sputtering TiO_x as resistive switching layers were fabricated successfully. Low-power characteristic with 1.52 μW set power (1 μA@1.52 V) and 1.12 μW reset power (1 μA@1.12 V) was obtained in the HfO₂/TiO_x resistive random-access memory (RRAM) devices by controlling the oxygen content of the TiO_x layer. Besides, the influence of oxygen content during the TiO_x sputtering process on the resistive switching properties would be discussed in detail. The investigations indicated that "soft breakdown" occurred easily during the electrical forming/set process in the HfO₂/TiO_x RRAM devices with high oxygen content of the TiO_x layer, resulting in high resistive switching power. Low-power characteristic was obtained in HfO₂/TiO_x RRAM devices with appropriately high oxygen vacancy density of TiO_x layer, suggesting that the appropriate oxygen vacancy density in the TiO_x layer could avoid "soft breakdown" through the whole dielectric layers during forming/set process, thus limiting the current flowing through the RRAM device and decreasing operating power consumption.