On the application of MoS2 monolayer for enhanced performance in metallic grating based plasmonic sensor structure

Abstract

Two dimensional (2D) materials are evolving as promising candidates for various optoelectronics applications. The distinctive structure and band gap properties make molybdenum disulfide (MoS2) a promising 2D material for applications in different biosensors (optical and electrochemical), solar cells, batteries and terahertz related areas. However, the application of MoS2 monolayer in metallic grating based plasmonic sensors is still unexplored. In view of its favourable characteristics at nanoscale level, the present work has analytically demonstrated the sensing application of gold (Au) grating structure deposited on MoS2 atop thin silver (Ag) layer. The considered substrate material is silicon dioxide (SiO2). Here, MoS2 will act as a protecting layer for Ag as well as strong adsorbing medium for different analytes (e.g., H2O, D2O, and gaseous media). The sensing performance of the proposed sensor is evaluated with rigorous coupled wave analysis in terms of figure of merit (FOM) and sensitivity. A significantly large FOM value of 72.77 RIU−1 and 89.74 RIU−1 are calculated for D2O-H2O and gaseous analyte systems, respectively. The FOM is found to be considerably improving for marginally thicker Ag layers owing to radiation damping effects. The effects of important dimensional parameters of grating on sensor’s performance parameters have also been discussed. Furthermore, an average FOM magnitude of 94.01 RIU−1 is obtained using the proposed sensor configuration for CO2 gas concentration (0.04–40%) in air. The present work will open new avenues for MoS2 in grating based plasmonic gas- and bio-sensors. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.