Artificial synapses based on two-dimensional van der Waals materials for brain-inspired computing

Abstract

Artificial electronic synapses with two-terminal floating-gate (FG) configurations have undergone enormous development because of the advantage in terms of easy modulation and quick fabrication. Although synaptic features can be effectively modulated via the FG field effect, the tunability remain limited, especially for the commonly used n-type transition metal dichalcogenides (TMDCs). This paper focuses on a two-terminal MoS2 FG artificial synaptic device, the surface of which has been functionalized by an ultrathin deposition (0.1 nm) of MoO3 on the channel region. The surface functionalization together with the gating effect greatly enhance hysteresis behaviors of the device with expanded memory window from 6 to 14.8 V and significantly increased ON/OFF current ratio from 10 to 107. In addition, essential synaptic functions were successfully emulated in this synaptic two-terminal device, including transition from short-term to long-term potentiation, paired-pulse facilitation/depression, and spike timing-dependent plasticity. These findings promise surface charge transfer doping as an effective method to broaden the functionality of two-dimensional TMDCs-based electronic devices and provide a platform for the development of electric-modulated neuromorphic architectures.