Bipolar resistive switching characteristics of cobalt-doped HfO₂-based memory films

In this work, the resistive switching behavior of HfO₂ and cobalt-doped (Co:HfO₂) films were demonstrated. X-ray photoelectron spectroscopy was used to explore the effect of Co dopants upon the chemical composition of HfO₂ film. Both films showed bipolar resistive switching behaviors, while the Co:HfO₂ film exhibited decreased switching voltages and narrower variations in the switching parameters, including voltages and resistances, than those of the HfO₂ film owing to the modulation of defects. The Pt/Co:HfO₂/Cu device also exhibited an increased ON/OFF ratio because of the increased resistance in the high resistance state, as well as good endurance and retention. The switching mechanisms for the fabricated devices were discussed based on the conductive filament model.