In-situ optical spectroscopy of ablation plume for preparations of nanostructured TiO2 thin films by pulsed laser deposition

Nanostructured TiO2 thin films on alpha-Al2O3 (0001) substrates prepared by pulsed laser deposition (PLD) were analyzed and evaluated in terms of the buffer 02 gas pressure (0-80 Pa) dependencies by optical spectroscopy and surface morphology. Optical emission spectra of the ablation plume from Ti and TiO2 targets were measured in-situ. The contribution from TiO molecules was observed by narrow-band photometry. The surface morphology was observed by an atomic force microscope (AFM), revealing the pressure dependence of nanostructures. The crystalline structures of prepared TiO2 thin films were observed by X-ray diffraction (XRD). The optically observed band-gaps of the prepared thin films show that the crystal structures are mixed crystals of rutile and anatase. Evaporated Ti particles combine with buffer O-2 gas thereby producing TiO molecules, which affect the formation of nanostructures on TiO2 thin films.