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

Publication date: Available online 2 December 2015
Source:Thin Solid Films
Author(s): Stefan Seeger, Klaus Ellmer, Michael Weise, Daniela Gogova, Daniel Abou-Ras, Rainald Mientus
Niobium-doped TiO2 films as highly transparent conducting oxides for electrical contacts were investigated. As-deposited films were amorphous and exhibited high resistivities ranging from 10 to 10⁵ 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 (α550nm <2x10³ 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>10²⁰ cm⁻³) increased with decreasing substrate temperature owing to metal-like phonon scattering in these samples.