Low-temperature Fabrication of Transparent Conducting Anatase Nb-doped TiO2 Films by Sputtering

We present a low-temperature (similar to 300 degrees C) process for preparing transparent conducting anatase Nb-doped TiO2 (TNO) polycrystalline films by sputtering. We first deposited amorphous films composed of an oxygen-rich bottom layer and oxygen-deficient top layer at room temperature. These films were then crystallized in a reducing atmosphere. The oxygen-rich bottom layer behaved as a seed layer during crystallization of the top layer, resulting in significant improvement of crystallinity and reduction of crystallization temperature. We obtained TNO polycrystalline films showing a resistivity of 6.4 x 10(-4) Omega cm and absorption below 10% in the visible region by post-deposition annealing at 400 degrees C. The developed low-temperature process was applied to fabricating TNO films on plastics and glass with low glass-transition temperature. (C) 2008 The Japan Society of Applied Physics