Impact of Cu electrode on switching behavior in a Cu/HfO₂/Pt structure and resultant Cu ion diffusion

In a newly proposed switching device using polycrystalline HfO₂ thin film with ion diffusion path, we have found that a Cu electrode could contribute to improved switching performance. Current-voltage measurements at room temperature revealed clear resistive switching, not accompanied by a forming process, in our Cu/HfO₂/Pt structure. The current step difference from one state to the other one was in the order of 10 ³-10⁴, giving a sufficient on/off ratio. Voltage sweep polarity suggested that filamentary Cu paths were formed due to Cu ion diffusion and annihilated at the HfO₂/Pt interface at reversed bias. This filament path formation and annihilation was the origin of the switching device performance.