Reproducible resistive switching in nonstoichiometric nickel oxide films grown by rf reactive sputtering for resistive random access memory applications

Ni1-δO binary oxide films were deposited on PtTi SiO2 Si substrates by radio-frequency reactive magnetron sputtering. The NiO-based metal-oxide-metal structures were fabricated for measurement of electrical properties. The electrical properties of the Pt Ni1-δO Pt structure as a function of growth temperature were investigated. The growth temperature was varied from room temperature to 400 °C. From all samples, negative resistance phenomenon and nonvolatile memory switching behavior were observed. The ratios between the high-resistance state (OFF state) and the low-resistance state (ON state) were larger than. 102. As the growth temperature was increased, both SET and RESET voltages increased due to the decrease of defects in nickel oxide films. On the basis of x-ray diffraction patterns, we confirmed that the defects in Ni1-δO film decreased with increasing the growth temperature due to sufficient diffusion and redistribution of adatoms. X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy analysis revealed that the nickel oxide films were Ni deficient and that Ni had three different Ni bond states caused by various defects in nickel oxide films. In order to investigate the influence of the upper limit of SET current (i.e., Compliance SET current), the compliance SET current was varied from 1 to 50 mA. This result showed that the ON-state current and the RESET voltage were strongly dependent on the magnitude of the compliance SET current. As the compliance SET current was increased, both the ON-state current and the RESET voltage increased due to the increase of the conducting path. The results suggest that the resistance switching behavior is related to the formation and fracture of the conducting path which is composed of defects in the nickel oxide film.