Ricerc@Sapienza

We present the design and fabrication of an evanescent waveguide sensor based on a-Si:H photodiodes for biomedical applications. The complete device presents a noise level lower than 2fA and a responsivity of 300mA/W at 532nm.

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.