A WSe 2 vertical field emission transistor

We report the first observation of a gate-controlled field emission current from a tungsten diselenide (WSe 2 ) monolayer, synthesized by chemical-vapour deposition on a SiO 2 /Si substrate. Ni contacted WSe 2 monolayer back-gated transistors, under high vacuum, exhibit n-type conduction and drain-bias dependent transfer characteristics, which are attributed to oxygen/water desorption and drain induced Schottky barrier lowering, respectively. The gate-tuned n-type conduction enables field emission, i.e. the extraction of electrons by quantum tunnelling, even from the flat part of the WSe 2 monolayers. Electron emission occurs under an electric field ~100 V ?m -1 and exhibits good time stability. Remarkably, the field emission current can be modulated by the back-gate voltage. The first field-emission vertical transistor based on the WSe 2 monolayer is thus demonstrated and can pave the way to further optimize new WSe 2 based devices for use in vacuum electronics. © The Royal Society of Chemistry.