The development of the physical and electrical characteristics of multi-layer TiO2–W–TiO2 thin films

Abstract

In this study, two different thin films, TiO2 thin film and TiO2–W–TiO2 multi-layer thin films (W, tungsten), are prepared by RF magnetron sputtering onto glass substrates. The crystal structure, morphology, and transmittance of TiO2 and TiO2–W–TiO2 multi-layer thin films are investigated by X-ray diffraction, SEM, and UV-Vis spectrometer, respectively. The amorphous, rutile, and anatase TiO2 phases are observed in the TiO2 thin film and in the TiO2–W–TiO2 multi-layer thin films. The deposition of tungsten as the inter-layer will have large effect on the transmittance and phase ratios of rutile and anatase phases in the TiO2–W–TiO2 multi-layer thin films. The crystal intensities of amorous TiO2 will decrease as the tungsten is used as the middle layer in the multi-layer structure. The band gap energy values of TiO2 thin film and TiO2–W–TiO2 multi-layer thin films are evaluated from (αhν)1/2 versus energy plots, and the calculated results show that the energy gap decreases from 3.21 eV (TiO2 thin film) to 3.08∼3.03 EV (TiO2–W–TiO2 multi-layer thin films).