  We have demonstrated selective gas sensing with molybdenum disulfide (MoS2)
thin films transistors capped with a thin layer of hexagonal boron nitride
(h-BN). The resistance change was used as a sensing parameter to detect
chemical vapors such as ethanol, acetonitrile, toluene, chloroform and
methanol. It was found that h-BN dielectric passivation layer does not prevent
gas detection via changes in the source-drain current in the active MoS2 thin
film channel. The use of h-BN cap layers (thickness H=10 nm) in the design of
MoS2 thin film gas sensors improves device stability and prevents device
degradation due to environmental and chemical exposure. The obtained results
are important for applications of van der Waals materials in chemical and
biological sensing.
