Semiconducting properties of the passive films on copper
Master of Arts
The semiconducting properties of the passive films on copper have been investigated through capacitance, photoresponse and kinetic measurements. Mott-Schottky plots show that the passive films on copper are p-type semiconductors. The metal deficits form the electron acceptors, which give rise to p-type conductivity. The passive films show photovoltages under illumination. The band gaps of the anodic films and thermal oxides are similar to that of CuO (1.7 eV). The band gap of the film formed in CuSOi+ is close to that of Q12O (2.2 eV). The electron transfer between the passive electrodes and the redox couple shows diffusion controlled kinetics. The large exchange current is explained in terms of the formation of an accumulation layer in the valence band.