Switching facilitated by the simultaneous formation of oxygen vacancies and conductive filaments in resistive memory devices based on thermally annealed TiO2/a-IGZO bilayers

Resistive random access memory (ReRAM) devices have been gaining popularity in recent years as prime contenders to achieve high-performance non-volatile memory, as such devices offer simple structure, good stability, and high performance and low power consumption. Here, we present a resistive memory based on the bilayer of 2 nm TiO2 and 20 nm amorphous indium-gallium-zinc oxide (a-IGZO) thin films. The device is fabricated on a glass substrate with indium-tin-oxide bottom and silver top electrodes. Annealing temperature of the active layer is optimized by a comparative study of the memory devices, resulting in the widest memory window at 350 °C. X-ray photoemission spectroscopy was utilized to assess the change in the film stoichiometry caused by the annealing process. A memory mechanism is proposed with the generation and migration of oxygen vacancies and the formation of conductive filaments. Based on the device characteristics under repeated sweeps, SET and RESET voltages are selected at 2.0 and −2.0 V respectively, with READ voltage at 0.2 V, demonstrating low voltage operation. The optimized ReRAM has good retention stability for more than 1000 s and its endurance stability exceeds 500 s. The applicability is demonstrated in a circuit with an a-IGZO-based thin film transistor.