An experimental study of the influence of solution resistivity and the effect of post-anodizing treatments of PS films on the electrical and optical properties of the metal/PS/Si photodiodes was performed. Porous silicon (PS) samples were made from p-Si in ethylene-glycol/HF or ethanol/HF solutions of different concentrations. The anodized sample was left in the dark for different times in the HF/base electrolyte in which the porous layer had been fabricated or in methanol. The results show a strong influence of the etching solution parameters and PS surface post-treatments on kinetic changes of the device's electrical properties. The mechanism of electrical conduction was interpreted in terms of charge carrier transport through shallow traps associated with the surface impurities. (C) 2002 Elsevier Science B.V. All rights reserved.