Influences of electrode materials on the resistive memory switching properties of ZnO_xS_1-x: Mn thin films

In this study, we investigate the effect of top electrode (TE) materials on the resistive switching characteristics of TE/ZnO_xS _1-x:Mn/Al devices. Al, Cu, Au, Ni, and ITO are used as the TE materials of our devices. Except for the ITO TE devices, all the devices show unipolar resistive switching and maintain memory characteristics even after 10⁴ s. The ratios of high resistance state (HRS) and low resistance state (LRS) for the Al, Cu, Au, and Ni TE devices are 10⁵, 10 ⁵, 10⁴, and 10², respectively. The low ratio of HRS and LRS of the Ni TE device is attributed to a high magnitude of current at HRS. The Cu/ZnO_xS_1-x:Mn/Al device shows the smallest distribution of set voltages. The ITO TE device exhibits bipolar resistive switching and suffers change in the resistance at HRS after 10³ s. Considering the distribution of set voltages and the ratio of HRS and LRS, Cu is the most suitable TE material for the TE/ZnO_xS_1-x:Mn/Al devices.