Temperature-dependence of resistive switching behaviors and tunneling mechanism of (111) epitaxial NiO films on metal seed layer

Abstract

Since 2000, resistive switching random access memory (ReRAM) based on binary metal oxide has become one of potential candidates for next generation of nonvolatile memory due to its simple structure, high writing/read speed (~5 ns), good endurance (~109 cycles), long retention time (~10 years) and low energy consumption (~ dozens of pJ). NiO has been extensively studied as one of promising materials applied for commercial ReRAMs. However, it exhibits diverse resistive switching (RS) behaviors that heavily dependent on fabrication technologies, methods and conditions. Up to now, RS performances and mechanisms of polycrystalline NiO films have been extensively investigated, while there are few discussions on RS performances of epitaxial NiO films, especially on metal seed layer. On the other hand, with the expanding scope of human activities, researches on stabilities of ReRAM devices under extreme environmental conditions are necessary. In this paper, temperature-dependence of RS behaviors and tunneling mechanism of epitaxial NiO(111) films on Pt seed layers have been discussed. A set of highly textured NiO(111) films on Pt seed layers were prepared by means of Radio Frequency magnetron sputtering. Their microstructural characteristics and temperature-dependence of RS performance were investigated. Microstructural investigation demonstrated the “cube-to-cube” lattice relationship of NiO(111)/Pt(001) interfaces. Under the applied electric field, the drift of oxygen ions in NiO film and the redox of Ag ions near upper electrodes result in the formation/rupture of oxygen-vacancy conductive filaments at a set/reset voltage lower than ± 1 V. Moreover, current-voltage ( I - V ) curves of Ag/NiO(111)/Pt memory cells exhibit stable bipolar switching behaviors in the temperature range from RT to 80°C. Moreover, their Arrhenius form (ln I vs. 1000/ T ) and Schottky tunneling (ln( I / T 2) vs. 1000/ T ) plots are the best linear fitting relationship. It reveals that the leakage current of Ag/NiO(111)/Pt memory cell on high resistance state can be explained by the Schottky tunneling mechanism.