Structural, electrical and optical properties of molybdenum-doped TiO2 thin films

Abstract Molybdenum doped TiO 2 (MTO) thin films were prepared by radio frequency (RF) magnetron sputtering at room temperature and followed by a heat treatment in a reductive atmosphere containing 90% N 2 and 10% H 2 . XRD and FESEM were employed to evaluate the microstructure of the MTO films, revealing that the addition of molybdenum enhances the crystallization and increases the grain size of TiO 2 films. The optimal electrical properties of the MTO films were obtained with 3 wt% Mo doping, producing a resistivity of 1.1×10 −3  Ω cm, a carrier density of 9.7×10 20  cm −3 and a mobility of 5.9 cm 2 /Vs. The refractive index and extinction coefficient of MTO films were also measured as a function of film porosity. The optical band gap of the MTO films ranged from 3.28 to 3.36 eV, which is greater than that of the un-doped TiO 2 film. This blue shift of approximately 0.14 eV was attributed to the Burstein–Moss effect.