Density effects of graphene oxide quantum dots on characteristics of Zr0.5Hf0.5O2 film memristors

Memristor characteristics have been reported to be enhanced by inserting graphene oxide quantum dots (GOQDs) in oxide layers. However, it has not been studied how the density of GOQDs affects the resistive switching behavior of memristor devices. In this work, memristor devices in the structure of Ag/Zr0.5Hf0.5O2 (ZHO)/GOQDs/ZHO/Pt are fabricated and tested. The device measurement results show that as the applied voltage is scanned, if the density of GOQDs increases, the resistance adjustment of fabricated memristor devices shifts from abruptly to gradually. Moreover, the resistance of a high-GOQD-density device is modulated by controlling the amplitude, width, polarity, and number of applied voltage pulses. Furthermore, the fabricated memristor device demonstrates basic synaptic behavior, including tunable conductance, short-term plasticity, long-term plasticity, spike-timing-dependent facilitation, and paired-pulse facilitation. These phenomena are attributed to the high density of GOQDs, which prevents Ag+ from migrating through the switching layers, and hence, the formation of Ag conductive filaments is slower. This study reveals that the proposed memristor device with an appropriate density of GOQDs has great potential in artificial electronic synaptic applications.