Pinch-Off Formation in Monolayer and Multilayers MoS Field-Effect Transistors.

The discovery of layered materials, including transition metal dichalcogenides (TMD), gives rise to a variety of novel nanoelectronic devices, including fast switching field-effect transistors (FET), assembled heterostructures, flexible electronics, etc. Molybdenum disulfide (MoS), a transition metal dichalcogenides semiconductor, is considered an auspicious candidate for the post-silicon era due to its outstanding chemical and thermal stability. We present a Kelvin probe force microscopy (KPFM) study of a MoS FET device, showing direct evidence for pinch-off formation in the channel by in situ monitoring of the electrostatic potential distribution along the conducting channel of the transistor. In addition, we present a systematic comparison between a monolayer MoS FET and a few-layer MoS FET regarding gating effects, electric field distribution, depletion region, and pinch-off formation in such devices.