Pristine and modified silicene based volatile organic compound toxic gas sensor: a first principles study

Abstract

In this work, we have investigated the sensitivity of two Volatile Organic Compounds (VOCs), formaldehyde (FD) and acetaldehyde (AD) on the surface of two-dimensional (2D) Armchair Silicene Nanoribbon (ASiNR) by analysing the structural, electronic and transport properties using density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalism. Different models of ASiNR have been considered viz; pristine, Al-doped, P-doped, Al/P co-doped and vacancy-defected ASiNR. The findings revealed that the vacancy-defected models shows a significant increase in the adsorption energies for both VOCs compared to other models. Apart from that, in all the models, the current increases with the applied voltage and the maximum value of current was found in Al/P co-doped model at a higher bias voltage of 2 V. The variation of the computed transmission spectrum peaks from −2 to 2 eV of energy values also confirms the sensitivity of the proposed models towards the VOC molecules. Moreover, the projected device density of states (PDDOS) revealed that all the models remain semiconducting before and after adsorption, which completely agrees with the transmission spectrum. Furthermore, Al/P co-doped model shows high sensitivity of 68% and77% towards FD and AD molecules respectively. Thus, it is concluded that the modeled ASiNR VOC gas sensors will aid in sensing cancer.