Simulation of surface-modified porous silicon photonic crystals for biosensing applications

In this work realistic biosensing structures based on the integration of porous silicon photonic crystals with polymer coating technology are presented. Microcavities and rugate filters are chosen as the photonic crystal configuration. The deposition of a polymer layer on the pore walls of these structures is proposed to improve the selectivity and sensitivity of the sensing function. A complete effective refractive index model including the polymer layer, the target and external effects like silicon oxidation has been developed in order to accurately simulate the structures. It is expected that the proposed structures could be used as low cost, highly integrated and highly sensitive biological sensors.

• Porous silicon photonic crystals (microcavities and rugate filters) as biosensing structures.
• A complete effective refractive index model is developed to simulate an optical response of the structures.
• Functionalisation of pore walls by a polymer layer does not deteriorate the response if the layer is thin.
• Silicon oxidation must be carefully controlled to avoid sensitivity degradation.