Fig. 3.

2D TMDC FET sensors for oxidizing and reducing gas detection. a Top and side views of favored configurations of NO₂ and NH₃ adsorbed on MoS₂ and in situ PL spectra of MoS₂ with NO₂ and NH₃. The insets present the difference in electron transfer process between gases and channel: NO₂ and NH₃ on the surface of MoS₂ act as electron acceptor and donor, respectively. Reprinted with permission from Ref. [16], Copyright 2015, Springer Nature. b Dynamic sensing responses of MoS₂ FET to NO₂ and NH₃ with different layer numbers of MoS₂. Reprinted with permission from Ref. [89], Copyright 2013, American Chemical Society. c Real-time response (relative conductance change) of p-type MoTe₂ FET sensor to NO₂ and n-type MoTe₂ FET sensor to NH3 under different gate biases. Reprinted with permission from Ref. [42], Copyright 2017, IOPscience