Surface transport and band gap structure of exfoliated 2H-MoTe 2 crystals

摘要: Semiconducting transition metal dichalcogenides (TMDs) have emerged as materials that can be used to realize two-dimensional (2D) crystals possessing rather unique transport and optical properties. Most research has so far focused on sulfur selenium compounds, while tellurium-based attracted little attention far. As a first step in the investigation of Te-based semiconducting TMDs this context, we studied MoTe2 with thicknesses above 4 nm, focusing surface quantitative determination gap structure. Using ionic-liquid gated transistors, show ambipolar at material is reproducibly achieved, hole electron mobility values between 10 30 cm2 V−1s−1 room temperature. The structure determined through three different techniques: transistors scanning tunneling spectroscopy, which allow measurement indirect (Eind), transmission spectroscopy thickness, enables both direct (Edir) gap. We find temperature Eind = 0.88 eV Edir 1.02 eV. Our results suggest thin layers may exhibit before mono-layer thickness. They should also drastically extend range gaps accessible 2D TMDs.