Refractive Index Sensing-Based Sensitivity Enhancement Using Surface Plasmon Resonance Sensor with Integration of Tin Diselenide and Zirconium Diselenide

A highly sensitive surface plasmon resonance (SPR) sensor is theoretically presented, including Silver (Ag), Tin Diselenide (SnSe2), Zirconium Diselenide (ZrSe2) and a sensing layer using the Kretschmann configuration. At the optimized thickness of the Ag layer, the sensitivity was measured using the angular interrogation method with a refractive index (RI) of 1.33–1.35. The sensitivity of the sensor was found to be 337.98°/RIU for a 2 nm SnSe2 layer thickness at RI of 1.34 and 320.94°/RIU for a 1 nm SnSe2 layer thickness at RI of 1.35 throughout with remarkable figure of merit (FoM) of 60.78/RIU and 64.57/RIU at 633 nm wavelength. The maximum sensitivity was achieved with 1 nm thickness of the SnSe2 layer. By systematically optimizing the Ag thickness, significant improvements in sensitivity, minimum reflectance (Rmin), detection accuracy (DA), and figure of merit (FoM) were achieved compared with the conventional Ag-only configuration. These additional SnSe2 layers increase the confinement of the electromagnetic field, increase the number of adsorption sites for biomolecules, and increase the effective change in the RI, resulting in larger shifts in the resonance angles. The proposed multilayer sensor provides a promising platform for high-performance, stable, and repeatable biosensing applications in chemical detection, environmental monitoring, and medical diagnostics, according to the results obtained.