(PHOTO)ELECTROCHEMICAL CHARACTERIZATION OF TIN-DOPED INDIUM OXIDE

Tin-doped indium oxide (ITO) films, prepared by dc magnetron sputterin g, were characterized by (photo)electrochemical measurements in aqueou s H2SO4 solutions. Wavelength dependent photocurrent measurements were used to determine the optical band gap energy of these films. Electro n excitation from the valence band to localized states in the band gap was observed. The presence of such energy levels resulted in an Urbac h tail. Impedance measurements were used to determine the flatband pot ential and the charge carrier concentration of ITO. A change in the ch arge carrier concentration due to different deposition conditions resu lted in a change of the resistivity and in a shift of the flatband pot ential. This shift could be explained by a Moss-Burstein shift of the optical band gap.