this study presents the electric behavior of sandwich devices based on porous silicon (ps) thin films with au/ps/si/cu structure when the material’s surface is exposed to different gases. ps thin films were fabricated by the electrochemical anodization method of si–c (100) substrates with resistivity 1.4-2.6 ωcm. samples were anodized in a solution of hf (48%), c2h5oh (99.98%) and distilled wat...