Field Effect Transistor Gas Sensors Based on Mechanically Exfoliated Van der Waals Materials

Abstract

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.

Enhanced NO2 Sensitivity of Vertically Stacked van der Waals Heterostructure Gas Sensor and Its Remarkable Electric and Mechanical Tunability

“…To validate the above model and demonstrate the enhanced performance and broad tunability of vdW heterostructure gas sensors, we opted for MoS 2 and WS 2 as suitable layered vdW materials. These materials were selected due to their semiconducting nature, along with their high carrier mobility, substantial current on–off ratios, and ultrafast charge transfer characteristics, as extensively reported in prior studies. − Additionally, the distinct adsorption energies for NO 2 with WS 2 and MoS 2 are 206 and 150 meV, , respectively. Finally, the adsorption of NO 2 on the surface of MoS 2 generates a flat band 0.4 eV above the Fermi level, while on WS 2 , the induced flat band is located near the Fermi level .…”

“…Upon exposure to NO 2 , NO 2 molecules adsorb onto the surfaces of both WS 2 and MoS 2 . The adsorption energies for WS 2 and MoS 2 when sensing NO 2 are 206 and 150 meV, , respectively. This suggests a more robust adsorption of NO 2 on WS 2 compared to MoS 2 .…”

Twisted van der Waals Quantum Materials: Fundamentals, Tunability, and Applications

“…This is exemplified in field effect transistor gas sensors that rely on mechanically exfoliated VdW materials. These sensors offer an appropriate framework to explore the Langmuir absorption model . Furthermore, gas sensors employing these materials frequently operate by detecting alterations in resistance or conductance upon exposure to gas molecules.…”

Chemiresistive Materials for Alcohol Vapor Sensing at Room Temperature

“…Changes of resistance, impedance or conductance in sensitive layer are induced by physical/chemical interaction with analytes molecules (e.g., chemiresistive sensors) [6][7][8][9] Electrochemical Changes of electrical current in an electrochemical cell are induced by oxidation or reduction of analytes molecules (e.g., amperometric sensors) [10,11] FET Changes of work function in a field effect transistor are induced by a charge transfer between the sensing material and the adsorbed analytes molecules (e.g., FET sensors, thin film field effect transistor TFT) [12][13][14] Capacitive Changes of dielectric constant of dielectric layer thickness are induced by physical/chemical interaction with analytes molecules (gas capacitors) [15] Gravimetric Changes of the vibration resonant frequency in an electromechanical oscillator are induced by the mass of adsorbed analytes (e.g., surface acoustic wave, micro/nano cantilevers) [16] Thermal Changes of thermal conductivity are induced by physical/chemical interaction with analytes molecules (e.g., MEMS) [17] Optical Changes of optical properties (absorption, fluorescence, reflection, refractive index, interferometry, optical path length, surface plasmon effects) are induced by physical/chemical interaction with analytes molecules (e.g., Fabry-Perot sensors; absorptive, reflective, and fluorescence-based sensors) [18][19][20] Magnetic Changes of magnetic properties (magnetization, spin orientation) are induced by physical/chemical interaction with analytes molecules (e.g., Hall effect-based magnetic sensors, Kerr effect-based magnetic sensors, magnetostatic surface spin wave oscillator MSSW) [21] Memristor Change of memristance in sensitive layer are induced by physical/chemical interaction with analytes molecules (e.g., gasistor) [22] Sensor devices also include memristors, an emerging technology, based on resistiveswitching phenomena. A memristor is a nonlinear electrical component theoretically described by Leon Chua in 1971 and commonly employed for digital memory applications.…”