Figure 4.

The minimum reflectivity in SPR curve as a function of the number of WS₂ layers at 660 nm excitation wavelength with various thickness of the gold thin film and silicon nanosheet (a) 0 nm (b) 5 nm (c) 7 nm; and the corresponding changes in the resonance angle for a fixed refractive index change in the biomolecular analyte (∆n_bio = 0.005) as a function of the number of layers of WS₂ at 660 nm excitation wavelength with various thickness of gold thin film and silicon nanosheet (d) 0 nm (e) 5 nm (f) 7 nm.