Epitaxial growth and properties of Nb-doped anatase TiO2 films on LSAT by MOCVD

High quality single crystalline Nb-doped anatase phase TiO2 films with different Nb concentrations were deposited on LSAT (100) substrates by metal organic chemical vapor deposition (MOCVD) at 600 °C. The influences of Nb concentration on the structural, electrical and optical properties of the films have been investigated. The obtained films were single crystalline anatase TiO2 and the epitaxial relationship between the films and the substrates was confirmed as TiO2 (001) || LSAT (100) with TiO2 [010] || LSAT [010]. The resistivity of the films was reduced by almost 8 orders of magnitude after Nb doping and a minimum resistivity of 4.0 × 10−2Ω⋅cm was obtained in 0.6% Nb-doped samples. The films achieved a maximum mobility as high as 13.5 cm2⋅V−1⋅s−1. The carrier concentration was in a range of 9.4 × 1017-1.7 × 1019 cm−3. The optical transmittance of the films in the visible range exceeded 93% and the optical band gap was varied from 3.48 to 3.53 eV.