Surface Photovoltage studies of Porous Silicon in presence of polluting gases: toward a selective gas sensor

摘要

The work function of nano Porous Silicon (PS) has been studied by the kelvin probe method as a function of the exposure to different gaseous species. Characterisation has been performed in dark and in presence of sub band and supra band gap light - Surface Photovoltage (SPV) measurements. Traces of ammonia and nitrogen dioxide change drastically the shape of SPV as a function of photon energy: light induces transitions from and to surface states produced by gas adsorption. The results foresee the possibility to improve semiconductor sensor selectivity by using monochromatic light at well denned frequency able to activate/deactivate surface states where species are adsorbed