Fig. 6

Schematic illustration of the underlying working mechanism of the Cu/ZrO₂/Pt device. a The CF illustration after P-Forming process. A Cu CF is formed to bridge the two electrodes. b The CF illustration after N-Forming process. An oxygen vacancy CF is formed to bridge the two electrodes. c The CF illustration after N-SET1 behavior. The main ingredient of the CF is Cu atoms. d The CF illustration after N-SET2 behavior. The main ingredient of the CF is oxygen vacancy