Electrochemical behaviour of thermally treated Cr-oxide films deposited on stainless steel

The semiconductive behaviour of amorphous and crystalline Cr-oxide films deposited on stainless steels was studied by capacitance and photoetectrochemical measurements. The amorphous films presented metallic behaviour. For the crystalline films, bandgaps were determined for direct and indirect transitions. Doping densities evaluated from Mott-Schottky plots were below 10(19) cm(-3) for the films treated at high temperature, and decreased with the treatment temperature. The crystalline films were described as a thick layer of non-stoichiometric chromium oxide with a bi-polar character. (C) 2002 Elsevier Science Ltd. All rights reserved.