It is shown that during a porous Si film formation by metal-stimulated etching a barrier layer is formed on a monocrystal p-Si substrate. The rectifying properties of the semiconductor structure can be explained by the fixation of the Fermi level in the near-surface layer of porous Si due to a high concentration of electrically active defects (deep centers or traps). It causes to energy bands bending and the appearance of a potential barrier. The study of Raman scattering showed the absence of size effects and a change in the band gap in the porous Si film. Activation energies of deep centers by the temperature dependence of the current-voltage characteristics and deep level transient spectroscopy study were determined.