Contact Engineering of MoS2 Synaptic Transistors via Reactive Ion Etching

Abstract

Artificial synaptic devices based on two-dimensional semiconductors are often achieved or regulated by introducing additional functional media or complex device architectures, such as solid electrolytes, floating gates, or heterostructures. Here, we demonstrate a simpler strategy to improve synaptic performance by applying localized CF₄/Ar reactive ion etching only to the MoS₂/metal contact region in a conventional back-gated MoS₂ transistor. The treatment induces controlled thinning of the contact-region MoS₂, together with defect formation and surface chemical changes. As a result, the contactetched devices show improved metal/semiconductor contact, with a clear evolution from Schottky-like to more Ohmic-like contact behavior. At the same time, the defect-rich etched contact region provides more active trapping sites, promoting charge trapping/detrapping and enlarge the memory window, resulting in enhanced synaptic characteristics, including short-term plasticity and paired-pulse facilitation. These results demonstrate that localized contact-region RIE provides a simple device-level strategy to link contact-injection modulation with synaptic response in conventional back-gated MoS2 transistors.