Fig. 4: Switching behaviors of the memristive devices with different Ge implantation fluences.

a–d Confirmation of the current-voltage characteristics for each conductance region by making devices with a Cu-based bilayer structure. The voltage was swept 100 times, following the sequence: 0 V → +7 V → 0 V → −7 V → 0. e–h Cumulative probability values of Ron and Roff for the memristive devices with varying Ge implantation fluences. All resistance values were measured at 1 V.