SEMICONDUCTING PROPERTIES OF TIO2 FILMS THERMALLY FORMED AT 480-DEGREES-C

Titanium oxide films, TiO2, were prepared on metallic titanium substrates employing a thermal treatment at 400 degrees C under normal air atmosphere, with various annealing times (15, 25 and 45 min). Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to study the electrochemical and electrical characteristics of these films. The potential range for the voltammetric measurements was -0.80 to 8.00 V vs MSE (mercurous sulfate reference electrode). An analysis of the capacitance values of these semiconducting oxide films gave information about their electronic characteristics. From Mott-Schottky plots the donor concentration (N-D) and the flat band potential (E(fb)) were obtained. ND values ranged from 14 x 10(22) cm(-3) to, 3.3 x 10(22) cm(-3), while E(fb) values ranged from -0.40 to -0.98 V vs MSE, depending on the heating times for the oxide growth. The thickness of the space charge region, calculated from the minimum value of the capacitance at high band bending, varied between 1.45 and 2.13 nm.