Heterostructure carbon-packed MoSSe nanospheres for flexible ReRAM and synapse devices

This paper reports on the synthesis of vacancy-assisted carbon-packed MoSSe (C@MoSSe) nanospheres and their use in memristor and neuromorphic devices. The heterostructure C@MoSSe nanospheres were fabricated using simple hydrothermal and sonication methods to synthesize large-scale, uniform C@MoSSe films on flexible substrates. The carbon skeleton, tightly adhered to the heterostructure MoSSe nanospheres, helped assign low sp 2 characteristics to the vacancies on the defective surfaces of the MoSSe nanospheres, thereby facilitating the realization of highly stable memristor and neuromorphic performance. In addition, the defects in the crystal lattice of the pure phase of MoSSe increased the band gap (around 4.39 eV) to be larger than the bulk and Janus structure of MoSSe (1.2 and 1.9 eV, respectively), resulting in carrier transport owing to trap filling. The C@MoSSe-based memristor successfully mimicked the basic and complex properties of synaptic plasticity, with a critical time window of around 460 μs, lower than that of the human brain. Bipolar memory performance, such as a high on/off current ratio, a reasonably low operating voltage, and stability, depended on the thickness of the C@MoSSe layers. The findings demonstrate the application potential of C@MoSSe-based memristors and can promote the realization of large-scale neuromorphic circuits. • Carbon-packed MoSSe (C@MoSSe) nanospheres for memristor and synapse devices. • C@MoSSe is fabricated using hydrothermal and density-gradient centrifugation method. • The memristor shows excellent endurance and retention due to the sp 2 nature of carbon. • A series of synaptic actions with a 460 μs time window are successfully mimicked.