Doping Concentration Modulation in Vanadium-Doped Monolayer Molybdenum Disulfide for Synaptic Transistors

Abstract

Doping is an effective way to modify the electronic property of two-dimensional (2D) materials and endow them with additional functionalities. However, wide-range control of the doping concentrations in monolayer 2D materials with large-scale uniformity remains challenging. Here, we report <i>in situ</i> chemical vapor deposition growth of vanadium-doped monolayer molybdenum disulfide (MoS₂) with widely tunable doping concentrations ranging from 0.3 to 13.1 atom %. The key to regulate the doping concentration lies in the use of appropriate vanadium precursors with different doping abilities, which also generate large-scale uniform doping to MoS₂. Artificial synaptic transistors were fabricated using the heavily doped MoS₂ as the channel material. Synaptic potentiation, depression, and repetitive learning processes were mimicked by the gate-tunable changes of channel conductance in such transistors with abundant vanadium atoms to trap/detrap electrons. This work develops a feasible method to dope monolayer 2D semiconductors and demonstrates their applications in artificial synaptic transistors.