Crystalline NaNbO₃ Thin Films Grown on a Sr₂Nb₃O₁₀ Seed Layer at Low Temperature for Self-Rectifying and Self-Powered ReRAM Devices

Crystalline NaNbO₃ (NN) thin films were deposited on a Sr₂Nb₃O₁₀/TiN/Si substrate at 300 °C. The Sr₂Nb₃O₁₀ (SNO) nanosheets served as a template to form the crystalline NN films at low temperatures. When the NN film was deposited on one SNO monolayer, the NN memristor exhibited normal bipolar switching characteristics, which can be attributed to the formation and destruction of oxygen vacancy filaments. Additionally, the NN memristor with one SNO monolayer exhibited artificial synaptic properties. However, the NN memristor deposited on two SNO monolayers exhibited self-rectifying bipolar switching properties and two SNO monolayers behaved as a tunneling barrier in the memristor. The conduction mechanism of the NN memristor with two SNO monolayers in the HRS is attributed to Schottky emission, direct tunneling, and Fowler–Nordheim (FN) tunneling. Hence, the NN self-rectifying switching memory device with SNO multilayer can be attributed to fabricating high-density cross-bar devices. Moreover, the piezoelectric energy harvester (PEH) was fabricated using the [001]-oriented NN film grown on SNO/Ni at 250 °C and the NN ReRAM devices have been operated using the NN thin film PEH.