Reactive Twin-magnetron Sputtering of Ti1-xNbxO2 Transparent Conducting Oxide Films

We obtained Ti1-xNxO2 (TNO) by doping Nb to TiO2. TNO transparent conducting film was fabricated by reactive midfrequency (MF) twinmagnetron sputtering method with assistance of a multicell anode layer ion sources, and the sputtering process was controlled by plasma emission monitor (PEM). The films were characterized by Xray diffraction (XRD), atomic force morphology (AFM), spectroscopic ellipsometry, spectrophotometer and xray photoelectron spectroscopy (WS). The behaviors of the carrier concentration and mobility of TNO thin films were investigated by means of the Hall technique. The results demonstrate that the reactive process can be controlled stably during the metaloxide transition with monitor of PEM, and the disadvantages of titanium target poison and anode disappear were also successfully overcome. Polycrystalline TNO thin films with 0.03 <= x <= 0.06 show a resistivity (rho) of lower than 2.0X103 Omega cm, and internal optical transmittance higher than 90% at 600 nm. The firstprinciple band calculations demonstrate that Ti2p, Nb3d and Ti3d states are strongly hybridized with each other to form dnature conduction band, substituted Nb atoms are ionized and release electrons into the hybridized conduction band without forming midgap state.