Electric Transport in Few-Layer ReSe 2 Transistors Modulated by Air Pressure and Light.

We report the fabrication and optoelectronic characterization of field-effect transistors (FETs) based on few-layer ReSe 2 . The devices show n-type conduction due to the Cr contacts that form low Schottky barriers with the ReSe 2 nanosheet. We show that the optoelectronic performance of these FETs is strongly affected by air pressure, and it undergoes a dramatic increase in conductivity when the pressure is lowered below the atmospheric one. Surface-adsorbed oxygen and water molecules are very effective in doping ReSe 2 ; hence, FETs based on this two-dimensional (2D) semiconductor can be used as an effective air pressure gauge. Finally, we report negative photoconductivity in the ReSe 2 channel that we attribute to a back-gate-dependent trapping of the photo-excited charges.