Working mechanism of a SiC nanotube NO_2 gas sensor

The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO_2 gas sensor system is established based on an (8, 0) silicon carbide nanotube (SiCNT) with a NO_2 molecule adsorbed. The transport properties of the system are studied with a method combining density functional theory (DFT) with the non-equilibrium Green's function (NEGF). The adsorbed gas molecule plays an important role in the transport properties of the gas sensor, which results in the formation of a transmission peak near the Fermi energy. More importantly, the adsorption leads to different voltage current characteristics of the sensor to that with no adsorption; the difference is large enough to detect the presence of NO_2 gas.