Due to their high surface area, monoatomic wall thickness, electronic structure (band gap, van Hove singularities) and properties (high mobility, ambipolar transport), single-walled carbon nanotubes (SWNTs) stand as a promising active material for chemical sensors. In a sensor context, they however suffer from lack of selectivity. For the same reasons that they are highly sensitive to analytes, they will be affected by their environment: interference from ambient gases (i.e. O₂ / H₂O redox couple) are to be expected [1,2], and vicinal charges and dipoles [3,4] will change the local electrostatics felt by the SWNTs. The dielectric environment being an integral part of the field-effect transistor (FET) stack, we sought to understand its effect on the transfer characteristics of devices with a carbon nanotube network as the active channel component.

References

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[2] Lefebvre, J. et al. Hysteresis free carbon nanotube thin film transistors comprising hydrophobic dielectrics. Appl. Phys. Lett. 107, 243301 (2015).

[3] Kobayashi, S. et al. Control of carrier density by self-assembled monolayers in organic field-effect transistors. Nat. Mater. 3, 317–322 (2004).

[4] Lee, S.-H. et al. Effect of Polymer Gate Dielectrics on Charge Transport in Carbon Nanotube Network Transistors: Low-k Insulator for Favorable Active Interface. ACS Appl. Mater. Interfaces 8, 32421–32431 (2016).