Polycrystalline TiO2 Thin Films with Different Thicknesses Deposited on Unheated Substrates Using RF Magnetron Sputtering

Different film thicknesses of polycrystalline TiO2 thin films deposited on various unheated substrates using radio frequency (RF) magnetron sputtering is investigated. The crystalline structure, optical properties, and surface morphology and roughness were measured using an X-ray diffractometer (XRD), a field-emission scanning electron microscope (FESEM), an atomic force microscope (AFM), and a UV-Vis spectrophotometer. Polycrystalline phases were formed on unheated substrates due to the plasma particle bombardment. Crystalline structures more easily formed on the glass substrate and only nanocrystalline structures formed on the ITO glass substrate due to the surface roughness of substrates. The absorption edge and optical band gap depended on the crystalline particle size and phase structure. The XRD results indicate that 500-nm-thick film on a glass substrate had the strongest intensities of mixed anatase and rutile phases.