Realization of Self-Rectifying and Self-Powered Resistive Random-Access Memory Memristor Using [001]-Oriented NaNbO₃ Film Deposited on Sr₂Nb₃O₁₀ Nanosheet at Low Temperatures

[001]-oriented NaNbO₃ films are deposited on Sr₂Nb₃O₁₀/TiN/SiO₂/Si substrates at 300 °C. The Sr₂Nb₃O₁₀ nanosheets are used as a template to form crystalline NaNbO₃ films at low temperature. The NaNbO₃ films deposited on one Sr₂Nb₃O₁₀ monolayer exhibit a bipolar switching curve due to the construction and destruction of oxygen vacancy filaments. Because the Sr₂Nb₃O₁₀ monolayer does not act as an insulating layer, the film does not exhibit self-rectifying properties. Self-rectifying properties are observed in the NaNbO₃ memristor, which forms on two Sr₂Nb₃O₁₀ monolayers that act as tunnel barriers in the memristor. The memristor exhibits extensive rectification and on/off ratios of 48 and 15.7, respectively. Tunneling is the current conduction mechanism of the device in the low-resistance state, and Schottky emission and tunneling are responsible for the conduction mechanism in the high-resistance state at low and high voltages, respectively. The piezoelectric nanogenerator produced using the [001]-oriented NaNbO₃ film generates high voltage (1.8 V) and power (3.2 μW). Furthermore, endurance of the resistive random-access memory and nonlinear transmission characteristics of the biological synapse are accomplished in the NaNbO₃ memristor powered by the NaNbO₃ nanogenerator. Therefore, the [001]-oriented crystalline NaNbO₃ film formed at 300 °C may be utilized for self-rectifying and self-powered artificial synapses.