Conduction and luminescent properties of wet porous silicon

Carrier transport and photoluminescence-quenching mechanisms in reverse-bia sed p-type porous silicon in contact with an aqueous electrolyte are invest igated. Concerning transport mechanisms investigation, experiments are base d on the study of the photo-induced current as a function of the porous lay er thickness. The liquid-impregnated porous silicon skeleton is found under equipotential conditions. Transport of electrons (supplied by the substrat e) in porous silicon is shown to be dominated by a diffusion process. Photo luminescence-quenching is investigated by using a reverse-biased p-type por ous silicon illuminated at 365 and 809 nm simultaneoulsy. The first illumin ation generate photoluminescence and the second supplies carriers in the su bstrate. A progressive photoluminescence-quenching has been observed, under a constant applied voltage, by increasing progressively the electron conce ntration in the porous layer. This original experiment allows to reject the hypothesis of an electric-field-induced separation of carriers as the phot oluminescence-quenching mechanism in wet porous silicon, while it strongly supports the mechanism based on Auger recombination.