Effect of Au electrode on the resistance change response of HfO x -based ReRAM device under voltage pulse trains

Abstract The demand for neuromorphic computing is increasing, and resistive random access memory (ReRAM) devices are intriguing candidates for synaptic applications. We studied a Ti/HfO x /Au ReRAM device with this potential in view, and fabricated a Ti/HfO x /Pt device for comparison. Both devices exhibited bipolar switching characteristics. In response to voltage pulse trains, gradual resistance change was observed in the Ti/HfO x /Au device for both the SET and RESET processes, indicating its suitability for artificial synapse application. In contrast, an abrupt resistance change was observed in the SET process of the Ti/HfO x /Pt device. A significant diffusion of Au atoms occurred in the HfO x layer of the Ti/HfO x /Au device, and the Au atoms were oxidized at the interface. This led to an increase in the O vacancy concentration, which assisted the achievement of the gradual resistance change. The present study indicates that the Ti/HfO x /Au device demonstrates good potential for use as an artificial synaptic device.