Retention mechanism of Cu-doped SiO₂-based resistive memory

Cu/SiO₂/Pt structures were fabricated to investigate their resistive switching behaviour and retention mechanisms. The device resistance can be reversibly switched between a high-resistance state (HRS) and a low-resistance state (LRS) by dc voltages, which can be explained using the conducting filament model with an electrochemical reaction. The HRS retention time was found to be much shorter than the LRS retention time. The HRS retention property degraded because of Cu diffusion within the SiO₂ layer and from the top Cu electrode; conversely, it was enhanced using an NH₃ plasma treatment which suppressed Cu diffusion. The HRS retention time was also influenced by the Cu concentration of the SiO₂ layer and the device area.