Capacity and Photocurrent Measurements at Passive Titanium Electrodes

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Abstract
The capacity and photocurrent behaviour of passive titanium electrodes has been investigated in dependence on the film thickness and the electrode potential, the photocurrents additionally on the wavelength. From capacity measurements a high donor concentration of 1020 cm−3 and a dielectric constant of D = 9 can be concluded. Compared to bulk TiO2 electrodes, the onset of the photocurrent is shifted to higher photon energies. The band gap is estimated to be Eg = 3.4 eV. At constant electrode potential ε the photocurrent decreases with increasing film thickness though the absorption of the film should be higher. This indicates the strong influence of the field strength in the film on the photocurrent which increases with thickness at constant field.