Influence of Stack Hybrid Configuration of MoS2 and Graphene on the Performance of Surface Plasmon Resonance Biosensor

Abstract

This paper investigates the influence of various configurations and flakes of: i) graphene, ii) graphene/MoS2/graphene and iii) MoS2/graphene/MoS2 over a thin layer of gold on the performance of a surface plasmon resonance (SPR) biosensor. The reflectance curves of the proposed SPR biosensor are obtained, analyzed and compared for different combinations and thicknesses of the biosensors’ layers in refractive indices (RI) of 1 and 1.02, resembling an air and a bacterial medium, respectively. An in-depth analysis based on finite difference time domain method is performed to describe the sensor response considering sensitivity, full width at half maximum and minimum reflectance. The obtained results show that the sensitivity of the biosensor with a 50 nm Au and a 5 nm TiO2 (as the adhesive layer between the Au- layer and the prism) is equal to 61°/RIU. In order to increase further the sensitivity, different stacks and thicknesses of MoS2/graphene/MoS2 and graphene/MoS2/graphene configurations on the Au layer are added. The achieved outcomes reveal that the sensitivity is improved for a monolayer of MoS2 (1L_MoS2) sandwiched between double layers of graphene (2L_G) on 50 nm Au and 5 nm TiO2 (1L_MoS2/2L_G/1L_MoS2/50nmAu/5nmTiO2/Prism-BK7). This combination yields a sensitivity of 71.5 °/RIU for RI changes in the sensing medium (Δn) of 0.02 with a great detection accuracy of 0.33. We hope that – based on the outcomes of this investigation - the proposed structures can open new windows to improve the SPR biosensor detection of biological species.