First-principles study of MoS_2, phosphorene and graphene based single electron transistor for gas sensing applications

摘要

Two dimensional single crystals like graphene, transition metal dichalcogenides, phosphorene, etc. can be useful for sensing applications due to their enhanced surface to volume ratio. A single electron transistor (SET) device made of such materials is proposed here as a futuristic low power device prototype for sensing purposes. The operation and performance of these SET devices are investigated for the first time using Density functional theory based Ab-initio calculations to understand their relative sensitivities towards sensing different gas molecules. The adsorption of CO, CO_2, NH_3 and NO_2 on monolayers of graphene, MoS_2 and phosphorene are investigated to find their most stable configurations and relative orientations on the host layers. The structural and electronic properties of the host layers have been found to be unaffected as a result of the adsorption processes. Phosphorene offers highest strength of physio-adsorption for all these molecules, indicating its superiority than the other two materials. It is observed that Phosphorene and MoS_2 are additionally sensitive towards the N-based molecules and magnetism could be induced in the presence of a paramagnetic molecule. Present results indicate that the charge stability diagram of the SET is unique for a specific gas molecule on the Two-dimensional (2D) layer and this is sensitive up to the addition/removal of a single molecule from the island. The wide temperature range of operation, extreme detection sensitivity and the versatility of the 2D materials for gas sensing make these SET devices very powerful candidates for practical application.