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Direct contacting of 2D nanosheets by metallic nanoprobes
* 1 , 1, 2 , 1, 2 , 1, 2 , 2 , 1, 2
1  CNR-SPIN Salerno Via Giovanni Paolo II 132, 84084 Fisciano, Salerno, Italy
2  Physics Department “E. R. Caianiello”, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, Salerno, Italy


We present a simple and fast methodology to realize metal contacts on two-dimensional nanosheets. In particular, we perform a complete characterization of the transport properties of MoS2 monolayer flakes on SiO2/Si substrates by using nano-manipulated metallic tips as metallic electrodes directly approached on the flake surface. We report a detailed experimental investigation of transport properties and contact resistance in back-gated field-effect transistor in which the Si substrate is used as the gate electrode. Moreover, profiting from the n-type conduction as well as the high aspect ratio at the edge of the MoS2 flakes, we also explored the possibility to exploit the material as a field emitter. Indeed, by retracting one of the metallic probes (the anode) from the sample surface, it has been possible to switch on a field emitted current by applying a relatively low external electric field of few tens of Volts for cathode-anode separation distance below 1µm. Experimental data are then analyzed in the framework of Fowler-Nordheim theory and its extension to the two-dimensional limit.

Keywords: Transition metal dichalcogenides; molybdenum disulfide; field emission; field-effect transistor