WS₂ and MoS₂ thin film gas sensors with high response to NH₃ in air at low temperature

Abstract

Abstract Transition metal dichalcogenides (TMDs) have received immense research interest in particular for their outstanding electrochemical and optoelectrical properties. Lately, chemical gas sensor applications of TMDs have been recognized as well owing to the low operating temperatures of devices, which is a great advantage over conventional metal oxide based sensors. In this work, we elaborate on the gas sensing properties of WS 2 and MoS 2 thin films made by simple and straightforward thermal sulfurization of sputter deposited metal films on silicon chips. The sensor response to H 2 , H 2 S, CO and NH 3 analytes in air at 30 °C has been assessed and both MoS 2 and WS 2 were found to have an excellent selectivity to NH 3 with a particularly high sensitivity of 0.10 ± 0.02 ppm −1 at sub-ppm concentrations in the case of WS 2 . The sensing behavior is explained on the bases of gas adsorption energies as well as carrier (hole) localization induced by the surface adsorbed moieties having reductive nature.