Thin film photosensor integrated on planar waveguide for lab-on-chip applications

We present a device based on amorphous silicon photosensors and glass-diffused waveguides to be used inside lab-on-chip systems, to perform biomolecular recognition by means of optical interaction with the analyte. A 150 × 300 μm2 p-i-n photosensor was fabricated on a 200 μm wide optical waveguide, by using standard thin film microelectronic techniques, such as: thermal diffusion processes, metals and dielectrics deposition, semiconductors growth, UV photolithography and wet-dry etching to define the structure geometries. The electro-optical characterization of the device shows the effectiveness of the optical coupling and suggests its use for on-chip detection in lab-on-chip applications.