No abstract

In this paper, we investigate the transport and optical properties of the monolayer semiconducting transition metal dichalcogenides (STMDs) in the absence and presence of the NH 3 , NO, NO 2 , and O 2 gas molecules to assess their potentials as gas sensors. The firstprinciples calculations based on density functional theory indicate that absorption of the O 2 , NO 2 , NO gas molecules on the surface of these materials leads to significant changes in their transmission spectrum. Our calculations predict a charge transfer between the adsorbent gas and any of these STMDs. However, the presence of NH 3 molecule has little effect on the transport properties of these materials. The results show that when the STMDs are exposed to NO, NO 2 , and O 2 molecules, the dielectric function changes. Therefore, these materials can be employed as the sensing element in an optical gas sensor.

Transition rules and optical properties of armchair graphene nanoribbons embedded in hexagonal boron nitride lattices are studied for the first time. Based on tight binding calculations considering first and second nearest neighbors, we show that the optical transition rules of such structures are completely different from that of conventional graphene nanoribbons. These rules are explained by the symmetry properties of the subband wave functions. The optical spectrum, the quantum efficiency, and the photoresponsivity of different nanoribbons are evaluated and their application in photodetector devices is investigated. The results are verified with first principles calculations.

No abstract