A PHOTOELECTROCHEMICAL STUDY ON ANODIC TANTALUM OXIDE-FILMS

Both anodic and cathodic photocurrents have been detected on tantalum oxide films depending on polarization. The optical band gap, E(g)opt, has been derived for anodic films grown in different conditions as wel l as for native oxides. Cathodic photocurrents at hv <E(g)opt have bee n attributed to electron injection at the metal/oxide interface. A cha nge in the sign of the photocurrent with the wavelength of the inciden t light has been observed near to the flat band potential. The latter has been estimated from the fitting of the photocurrent vs potential c urves.