Surface Plasmon Resonance on Gold and Silver Films Coated with Thin Layers of Amorphous Silicon−Carbon Alloys

The paper reports on a novel surface plasmon resonance (SPR) substrate architecture based on the coating of a gold (Au) or silver (Ag) substrate with 5 nm thin amorphous silicon−carbon alloy films. Ag/a-Si1−xCx:H and Au/a-Si1−xCx:H multilayers are found to provide a significant advantage in terms of sensitivity over both Ag and Au for SPR refractive index sensing. The possibility for the subsequent linking of stable organic monolayers through Si−C bonds is demonstrated. In a proof-of-principle experiment that this structure can be used for real-time biosensing experiments, amine terminated biotin was covalently linked to the acid-terminated SPR surface and the specific streptavidin−biotin interaction recorded.