Threshold voltage control of carbon nanotube-based synaptic transistors via chemical doping for plasticity modulation and symmetry improvement

Threshold voltage control of two-dimensional semiconductors enabled field-effect transistors (FETs) exhibits great potential for high-performance electronic and optoelectronic devices. However, few studies have paid attention to the threshold voltage tunability for the plasticity modulation of neuromorphic devices. Herein, a feasible chemical doping method was demonstrated to effectively modulate the electrical property of carbon nanotube-based FETs (CNFETs). The threshold voltage of CNFETs could be gradually adjusted by varying the doping concentration, annealing temperature, and annealing time. Moreover, pronounced hysteretic behaviors induced by the charge trapping/de-trapping process via the interface exhibited a strong dependence on AuCl₃ doping, which provided a unique opportunity to emulate tunable synaptic plasticity. By AuCl₃ doping, both excitatory and inhibitory synaptic behaviors were enhanced and an improved symmetry contributed to an increased recognition accuracy (∼98%) for the recognition of handwritten digits. This work provides an alternative strategy for plasticity modulation by chemical doping to develop future neuromorphic devices.