Enhancement of nitride-gas sensing performance of SiC7 monolayer induced by external electric field

Abstract

The geometrics, adsorption energy, charge transfer, electronic and optical properties of molecules (NO, NH3, NO2, H2, N2, O2 and CO2) adsorbed on the SiC7 monolayer with and without electric field were studied using first principles calculations. Our results show that the SiC7 monolayer has high sensitivity and selectivity toward NO, NH3, and NO2 monitoring. However, the strong interaction between the three molecules and monolayer makes it difficult for molecules desorption from the SiC7 monolayer, and resists the monolayer as a reusable gas sensor. When an external vertical electric field is applied, the adsorption energy can be decreased obviously, thereby effectively decrease the recovery time. In addition, the applied electric field can also effectively modify the electronic and optical properties of molecules adsorbed on the SiC7 monolayer. Our results indicate that the gas-sensing performance of the SiC7 monolayer toward NO, NO2, and NH3 can be significantly improved by applying an external electric field. Therefore, it is predicted that the SiC7 monolayer is a promising candidate for reusable gas sensors with high sensitivity and selectively for detecting NO and NH3 gases at room temperature with the applied electric field, and a disposable gas sensor for detecting NO2 gas.