Engineering of the resistive switching properties in V₂O₅ thin film by atomic structural transition: Experiment and theory

Bipolar resistive switching has been reported in ITO/V₂O₅/ITO structures. Synthesized from the sol-gel process, the nanostructured V₂O₅·nH₂O xerogel thin film endures significant structural transition during the post-annealing step. The impact of the structural transition of the V₂O₅ film on the resistive switching properties is studied in this work. The switching voltage decreases from 6.5 V to 3.0 V when the annealing temperature increases from 220 °C to 280 °C and then increases up to 5.0 V at 350 °C. Above the annealing temperature of 350 °C, the reversible switching characteristics disappear. The thermogravimetric measurement shows that intercalated H₂O molecules fully evaporate above 350 °C. X-ray diffraction shows that the xerogel phase gradually vanishes as the annealing temperature increases, and only α-V₂O₅ and β-V₂O₅ exist at high annealing temperatures. Ab initio simulations are performed to evaluate the formation energies of the oxygen vacancy in xerogel, α-V₂O₅, and β-V₂O₅ phases. The results are in good agreement with the experiments: the formation energy of the oxygen vacancy is significantly lower in xerogel than in α-V₂O₅ and β-V₂O₅, enabling the occurrence of reversible switching when the xerogel phase exists in the sandwich structure.