Reactive magnetron sputtering of Nb-doped TiO2 films: Relationships between structure, composition and electrical properties

Abstract Niobium-doped TiO 2 films as highly transparent conducting oxides for electrical contacts were investigated. As-deposited films were amorphous and exhibited high resistivities ranging from 10 to 10 5 Ω cm. A slight oxygen deficiency in as-deposited films was essential to gain low resistivities (10 − 3 Ω cm) and low optical absorption coefficients ( α 550 nm 3 cm − 1 ) in the annealed films. Therefore, we controlled the oxygen stoichiometry during the film deposition by adjusting the magnetron discharge voltage, while the oxygen gas flow was kept constant. The Hall mobility of degenerately doped films (electron concentration > 10 20 cm − 3 ) increased with decreasing substrate temperature owing to metal-like phonon scattering in these samples.