Synaptic MoS2 transistors based on charge trapping two-dimensionally confined in Sr2-xCoxNb3O10 nanosheets

Abstract

Two-dimensional (2D) synaptic devices based on charge trap/de-trap have attracted much attention due to their superior characteristics that is gate tunability, large switching ratio, long-term retention, and distinct synaptic potentiation/depression with low power. Here, we introduce a 2D Sr2-xCoxNb3O10 (SCNO) nanosheet layer be-tween the MoS2 channel and SiO2 substrate because charge trap sites confined in SCNO nanosheet layer are anticipated to precisely control the 2D channel conductance. The hysteretic and synaptic behaviors of MoS2 channel can be controlled by charge trap/de-trap in two-dimensionally confined nanosheet layer with different doping ratio of Co. As the x value for the MoS2/SCNO field effect transistor (FET) increases, the shift of the threshold voltage (Vth) in a transfer curve increases and more linear potentiation/depression curves are induced with lower gate voltage pulse. In addition, paired-pulse facilitation is successfully implemented in a MoS2/SCNO FET. Therefore, our results suggest the feasibility of improved and efficient emulation of biological synaptic behavior in MoS2 transistors in contact with 2D oxide nanosheet layer.