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-Si_1?xC _x:H and Au/a-Si_1?xC_x: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.