Chemical sensor based on porous silicon dual transducers.

Novel porous Si exhibiting dual optical properties, both Fabry-Perot fringe (optical reflectivity) and photoluminescence, were developed and used as chemical sensors. Porous Si samples were prepared by an electrochemical etch of p-type silicon under the illumination with a 300 W tungsten filament bulb for the duration of etch. The surface of porous Si was characterized by FT-IR instrument. The porosity of samples was about 80%. Both reflectivity and photoluminescence were simultaneously measured under the exposure of organic vapors. The shift of Fabry-Perot fringe to the longer wavelength under the exposure of chloroform vapors was obtained. The steady-state photoluminescence spectra and quenching photoluminescence under the exposure of various organic vapors were obtained. A set of organic compounds were analyzed by both quenching photoluminescence and change of optical thickness.