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

Abstract

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.