STUDY OF ELECTRONIC STRUCTURE OF TIN-DOPED In2O3 (ITO) FILM DEPOSITED ON GLASS
and Asghar Zeini-Isfahani
Department of Chemistry, University of Isfahan, 81745, Isfahan, Iran
Electronic properties of lowly tin doped In2O3 (ITO) electrode with nanoscale particles (ca. 36 nm) prepared by electron-beam evaporation on glass substrate in contact with 0.1 mol dm-3 H2SO4 solution under visible light was investigated by means of linear sweep voltammetry and electrochemical impedance spectroscopy techniques. Differential capacitance results showed that in the high frequency region of EIS data, ITO and impurity element oxides may develops a p-n junction (Esaki tunnel diode) with low charge carrier concentration (ND = 2.07×109 cm-3). In this EIS data region, a reverse semicircle with a negative resistance was appeared. In contrast, in the low frequency region of EIS data, these semiconductors were converted into only n-type one. The flat-band potential of ITO film at low frequency region as determined from capacitance measurements was found to be around -0.0344 volt vs. SCE. Also, from the slope of linear portion of Mott-Schottky plot, charge carrier concentration was calculated to be about ND = 7.1501×1021 cm-3.
Key words: EIS, Mott-Schottky plot, electronic structure, electron beam evaporation, ITO