Growth parameter-dependent functional properties of polycrystalline Nb:TiO2 thin films deposited at room temperature
Abstract
Transparent conducting oxides (TCOs) are the important class of materials having potential applications in optoelectronic devices, solar cells, liquid crystal displays (LCDs) and light emitting diodes (LEDs). In this work, the structural, chemical and electro-optical properties of Nb:TiO2 films was investigated using XRD, XPS, UV-visible-NIR spectroscopy and van der Paw and Hall method. The films were deposited on glass, silicon and polymer substrates by RF sputtering and were subsequently annealed under the argon atmosphere at 350 °C. The lowest resistivity obtained on glass substrate was 7.45 × 10-4 Ω.cm with average visible transmittance of 78 %. The figure of merit of the prepared Nb:TiO2 films is comparable to state of the art tin doped indium oxide. Our work indicates that the conductivity of the films is strongly correlated with the crystalline structure particularly on the amount of anatase phase with respect to rutile and with the oxygen vacancies in the films. "