posted on 2023-03-27, 19:03authored byYue Zhao, Gang Wu, Kuan-Ming Hung, Jiung Cho, Miri Choi, Cormac Ó Coileáin, Georg S. Duesberg, Xiang-Kui Ren, Ching-Ray Chang, Han-Chun Wu
The high surface-to-volume ratio and flatness of mechanically
exfoliated
van der Waals (vdW) layered materials make them an ideal platform
to investigate the Langmuir absorption model. In this work, we fabricated
field effect transistor gas sensors, based on a variety of mechanically
exfoliated vdW materials, and investigated their electrical field-dependent
gas sensing properties. The good agreement between the experimentally
extracted intrinsic parameters, such as equilibrium constant and adsorption
energy, and theoretically predicted values suggests validity of the
Langmuir absorption model for vdW materials. Moreover, we show that
the device sensing behavior depends crucially on the availability
of carriers, and giant sensitivities and strong selectivity can be
achieved at the sensitivity singularity. Finally, we demonstrate that
such features provide a fingerprint for different gases to quickly
detect and differentiate between low concentrations of mixed hazardous
gases using sensor arrays.