Transparent conductive Nb-doped TiO2 films deposited by direct-current magnetron sputtering using a TiO2-x target

Nb-doped anatase TiO2 films were deposited on unheated glass by dc magnetron sputtering using a slightly reduced TiO2-x target (2-x= 1.986; conductivity, 3.7 S cm(-1); density, 4.21 g/cm(3)) with Nb2O5 pellets on it. After post-annealing in a vacuum (6 x 10(-4) Pa) at 400 degrees C for 1 h, these films were crystallized into a polycrystalline anatase TiO2 structure. The resistivity of the films decreased to 1.3 x 10(-3) Omega cm with increasing Nb concentration up to 6.4 at.%, where the carrier density was 1.3 x 10(21) cm(-3) and the doping efficiency was estimated to be 65%. Such films exhibited high transparency of over 60-70% in the visible light region. (C) 2007 Elsevier B.V. All rights reserved.