DOI: 10.1007/s11534-005-0009-3 Research article CEJP 4(1) 2006 105–116 Structural study of TiO 2 thin films by micro-Raman spectroscopy Ahti Niilisk * , Mart Moppel, Martti P¨ ars, Ilmo Sildos, Taavi Jantson, Tea Avarmaa, Raivo Jaaniso, Jaan Aarik Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia Received 8 August 2005; accepted 5 October 2005 Abstract: The Raman spectroscopy method was used for structural characterization of TiO 2 thin films prepared by atomic layer deposition (ALD) and pulsed laser deposition (PLD) on fused silica and single-crystal silicon and sapphire substrates. Using ALD, anatase thin films were grown on silica and silicon substrates at temperatures 125–425 ◦ C. At higher deposition temperatures, mixed anatase and rutile phases grew on these substrates. Post-growth annealing resulted in anatase-to-rutile phase transitions at 750 ◦ C in the case of pure anatase films. The films that contained chlorine residues and were amorphous in their as-grown stage transformed into anatase phase at 400 ◦ C and retained this phase even after annealing at 900 ◦ C. On single crystal sapphire substrates, phase-pure rutile films were obtained by ALD at 425 ◦ C and higher temperatures without additional annealing. Thin films that predominantly contained brookite phase were grown by PLD on silica substrates using rutile as a starting material. c  Central European Science Journals Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved. Keywords: Titanium dioxide, thin films, atomic layer deposition, pulsed laser deposition, Raman spectroscopy PACS (2006): 68.55.J; 78.30.Hv; 81.15.-z 1 Introduction Metal oxides comprise compounds that have been widely studied because of their impor- tant applications. For instance, in the last 5–6 years, oxides with wide band-gap and high dielectric constant, known as high-k oxides [1–5], have attracted great attention in the * E-mail: niilisk@fi.tartu.ee Unauthenticated Download Date | 2/23/16 9:27 AM