In
this work, we develop a gate-tunable gas sensor based on a MoS2/hBN heterostructure field effect transistor. Through experimental
measurements and numerical simulations, we systematically reveal a
principle that relates the concentration of the target gas and sensing
signals (ΔI/I
0)
as a function of gate bias. Because a linear relationship between
ΔI/I
0 and the gas
concentration guarantees reliable sensor operation, the optimal gate
bias condition for linearity was investigated. Taking NO2 and NH3 as target molecules, it is clarified that the
bias condition greatly depends on the electron accepting/donating
nature of the gas. The effects of the bandgap and polarity of the
transition metal dichalcogenides (TMDC) channel are also discussed.
In order to achieve linearly increasing signals that are stable with
respect to the gas concentration, a sufficiently large V
BG within V
BG > 0 is required.
We expect this work will shed light on a way to precisely design reliable
semiconducting gas sensors based on the characteristics of TMDC and
target gas molecules.
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