Contribution (Oral/Poster/Keynote) Monolayer transition metal dichalcogenide based field-effect transistors

A great deal of interest in two-dimensional materials analogues of graphene has appeared among the scientific community since the demonstration of isolated 2D atomic plane crystals from bulk crystals [1]. Dimensionality is key for the definition of material properties and the same chemical compound can exhibit dramatically different properties depending on whether it is arranged in dots (0D), wires (1D), sheets (2D) or bulk (3D) crystal structure. Notably, experimental studies of 2D atomic crystals were lacking until recently because of the difficulty in their identification [1]. Representative of this class are the 2D monolayer of transition metal dichalcogenides (TMD) with a chemical formula MX2, where M stands for a transition metal and X for Se, S, or Te. The potential of this family of layered materials for flexible electronics was proposed by Podzorov et al., who demonstrate an ambipolar WSe2 p-FET with a hole mobility comparable to silicon (500 cm/V-s) [2]. The electronic properties of TMDs vary from semiconducting (e.g., WSe2) to superconducting (e.g., NbSe2). The semiconducting monolayer TMDs, like MoS2, MoSe2, MoTe2, WS2, and WSe2 are predicted to exhibit a direct gap in the range of 1–2 eV [3]. The wide gap together with a promising ability to scale to short gate lengths because of the optimum electrostatic control of the channel, by virtue of its thinness, make monolayer TMDs very promising for low power switching and optoelectronics applications. The first 2D crystal based FET relying on a semiconducting analogue of graphene was demonstrated using a monolayer MoS2 as the active channel [4]. Low power switching with an ION/IOFF10 and subthreshold swing (SS) of 74 mV/decade at room temperature, was experimentally measured. More recently, a monolayer p-type WSe2 FET with an optimum SS  60 mV/decade and ION/IOFF >10 was demonstrated [5].