Adsorption behavior of small molecule on monolayered SiAs and sensing application for NO2 toxic gas

Owing to the ultrahigh surface-to-volume ratio and excellent carrier transport property, two-dimensional (2D) materials are regarded as most promising candidates for gas sensor with high sensitivity. Using the first principles calculations, we have examined the adsorption behavior of typical gas molecules on the 2D SiAs monolayer. The monolayered SiAs could sensitively response physical absorption of SO2, O2, NO, and NO2 molecule due to substantial charge transfer, and these molecules have introduced various defective states around the Fermi level. Most importantly, the quantum transport calculations have shown that the I–Vb behavior is substantially enhanced due to the toxic gas absorption. Specifically, striking improvement on transport performance is induced by NO2 absorption due to remarkable charge transfer, making the SiAs monolayer a promising candidate to selectively and sensitively detect NO2 molecule. Furthermore, we have shown that the work function and the charge transfer can be manipulated by strain, allowing potential application for anisotropic electronics. Our findings could be helpful to the potential application of the NO2 toxic detection in future.