Environmental Effects on the Electrical Characteristics of Back-Gated WSe(2) Field-Effect Transistors

We study the effect of polymer coating, pressure, temperature, and light on the electrical characteristics of monolayer [Formula: see text] back-gated transistors with [Formula: see text] contacts. Our investigation shows that the removal of a layer of poly(methyl methacrylate) (PMMA) or a decrease of the pressure change the device conductivity from p- to n-type. From the temperature behavior of the transistor transfer characteristics, a gate-tunable Schottky barrier at the contacts is demonstrated and a barrier height of [Formula: see text] 70 meV in the flat-band condition is measured. We also report and discuss a temperature-driven change in the mobility and the subthreshold swing that is used to estimate the trap density at the [Formula: see text] interface. Finally, from studying the spectral photoresponse of the [Formula: see text] , it is proven that the device can be used as a photodetector with a responsivity of [Formula: see text] at [Formula: see text] and [Formula: see text] optical power.