Conduction and switching behavior of e-beam deposited polycrystalline Nb2O5 based nano-ionic memristor for non-volatile memory applications

Highlights: • Nb₂O₅ thin film based non-volatile memories with Pt and BCP as top electrodes fabricated by e-beam evaporation method. • The bipolar resistive switching nature of Nb₂O₅ thin film under a low operational voltage i.e. < ± 1 V has been demonstrated. • Excellent non-volatility followed by reproducible resistive switching behavior has been observed. -- Abstract: Investigation has been done of bipolar resistive switching mechanism of Pt/Nb₂O₅/Pt and Bare conductive paint (BCP)/ Nb₂O₅/Pt memristive devices with orthorhombic phase prepared by e-beam evaporation method. The device exhibits reproducible switching with a ratio of (R_off/R_on) of 20 or higher which is good enough in read out for practical memory devices. The device exhibits reversible switching and better consistency during the switching from a high resistance state to a low resistance state and vice versa under a low operational voltage ( < ±1 V) due to its controlled formation and/or annihilation of conduction path. Switching mechanism is elucidated using a model invoking drift and diffusion of oxygen vacancies for the formation and rupture of conduction path during the Set and Reset process. The as deposited Nb₂O₅ thin film shows itself as amorphous in nature and transferred to orthorhombic phase by post annealing at 600 °C/30 min in O₂ ambient. The reliability test of memristive device stack structures has been investigated by observing the retention of 600 min and reproducible switching through endurance test of over 1000 cycles which is better than the reported structures employing single layer of Nb₂O₅. The device does not show any performance degradation during the test.