Selective chemical vapor sensing with few-layer MoS₂ thin-film transistors: Comparison with graphene devices

We demonstrated selective gas sensing with MoS₂ thin-film transistors using the change in the channel conductance, characteristic transient time, and low-frequency current fluctuations as the sensing parameters. The back-gated MoS₂ thin-film field-effect transistors were fabricated on Si/SiO₂ substrates and intentionally aged for a month to verify reliability and achieve better current stability. The same devices with the channel covered by 10 nm of Al₂O₃ were used as reference samples. The exposure to ethanol, acetonitrile, toluene, chloroform, and methanol vapors results in drastic changes in the source-drain current. The current can increase or decrease by more than two-orders of magnitude depending on the polarity of the analyte. The reference devices with coated channel did not show any response. It was established that transient time of the current change and the normalized spectral density of the low-frequency current fluctuations can be used as additional sensing parameters for selective gas detection with thin-film MoS₂ transistors.