Improved contact resistance in ReSe2 thin film field-effect transistors

We report the fabrication and device characteristics of exfoliated, few-layer, ReSe2 field effect transistors (FET) and a method to improve contact resistance by up to three orders of magnitude using ultra-high-vacuum annealing (UHV). Many devices were studied in the absence of light and we found an average contact of 750 Ω · cm after UHV treatment. The median FET metrics were similar to other transition metal dichalcogenides: field effect mobility ∼6.7 cm2/V · s, subthreshold swing ∼1.2 V/decade, and Ion/Ioff ∼ 105. In devices with low Rc current saturation was observed and is attributed to injection limited transport.