Structural investigation and electronic band transitions of nanostructured TiO2 thin films

Abstract

Titanium dioxide (TiO2) thin film was deposited on n-Si (100) substrate by reactive DC magnetron sputtering system at 250 degrees C temperature. The deposited film was thermally treated for 3 h in the range of 400-1000 degrees C by conventional thermal annealing (CTA) in air atmosphere. The effects of the annealing temperature on the structural and morphological properties of the films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. XRD measurements show that the rutile phase is the dominant crystalline phase for the film annealed at 800 degrees C. According to AFM results, the increased grain sizes indicate that the annealing improves the crystalline quality of the TiO2 film. In addition, the formation of the interfacial SiO2 layer between TiO2 film and Si substrate was evaluated by the transmittance spectra obtained with FTIR spectrometer. The electronic band transitions of as-deposited and annealed films were also studied by using photoluminescence (PL) spectroscopy at room temperature. The results show that the dislocation density and microstrain in the film were decreased by increasing annealing temperature for both anatase and rutile phases. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim