Effect of oxidizable electrode material on resistive switching characteristics of ZnOxsS_1-x films

We investigate the memory characteristics of ZnO_xS_1-x based resistive switching random access memory (ReRAM) devices with Al and Pt bottom electrodes (BEs). Both the ReRAM devices with Al and Pt BEs exhibit unipolar resistive switching behaviors, regardless of the materials of the BEs. The ratios of the high resistance state (HRS) to the low resistance state (LRS) of the Au/annealed ZnO_xS_1-x/Al and the Au/annealed ZnO_xS_1-x/Pt devices are more than 10⁶ and 10⁴, respectively. The HRS depends more significantly on the material of the BE than the LRS. The resistance in the HRS of the device with the Al BE is more stable in the endurance characteristics and higher in magnitude than that of the device with the Pt BE. For an anealed ZnO_xS_1-x/Al film, the oxygen signal in the auger depth profile shows the formation of an AlO_x layer at the interface between the annealed ZnO_xS_1-x layer and the Al BE. The difference between the memory characteristics of the annealed ZnO_xS_1-x devices with the Al and Pt BEs is explained with the presence or absence of the oxidized layers formed in the interfaces between the annealed ZnO_xS_1-x films and the BEs.