Mechanism for an enhanced resistive switching effect of bilayer NiOx/TiO2 for resistive random access memory

Bilayer of NiOx/TiO2 thin film spin-coated and sputtering-deposited on the fluorine doped tin oxide (FTO) substrate is employed to develop a resistive random access memory device. An enhanced resistive switching (RS) behavior, which with appropriate resistance ratio of ∼103, switching cycle endurance for 102 and long retention time for 104 s, is observed in the bilayer NiOx/TiO2 based device. Construction of contact-potential barrier, formation and rupture of a localized conduction filaments and migration of oxygen vacancy existed in the interface near electrodes co-contribute to the enhanced RS memory effects, but the migration of Ag+, Ni2x+ and diffusion of oxygen vacancies are the dominated ones. This work might give an insight into the mechanism of RS memory behaviors of an oxide-stacked structure device.