Tailoring surface enhanced Raman scattering platform based on pulsed laser deposited MoS2 - Ag hybrid nanostructure

Abstract

Surface enhanced Raman scattering (SERS), is a widely used sensing technique in which Raman scattering by molecules is significantly enhanced by adsorbing the molecules onto corrugated metal surfaces enabling even single molecular detection. In the present work, we focus on the development of SERS substrate based on MoS2 film fabricated using pulsed laser deposition (PLD) technique taking advantage of the charge transfer interaction between MoS2 film and the probe molecule. Rhodamine 6G (R6G) is used as the probe molecule for the qualitative evaluation of SERS performance of the fabricated substrates. Additionally, silver nanoparticles (Ag NPs) are deposited on the PLD grown MoS2 film and is developed as SERS substrate. SERS performance is optimised by varying deposition time during the fabrication of MoS2 film and also by altering the concentration of Ag NPs. The enhancement depends on both the number of MoS2 layers and on the distribution of Ag NPs. Simulation based on finite difference time domain (FDTD) method is used to validate this result. Enhancement factor of the order of 105 and 108 is obtained for the monolayer MoS2 film and for the optimised MoS2 - Ag hybrid films respectively.