Title: Physical and optical waveguiding properties of sol-gel deposited nano-structured TiO₂ thin films: a study on the effect of synthesis parameters

Authors: Mohamed Atoui; Tahar Touam; Ilhem Hadjoub; Azeddine Chelouche; Boubekeur Boudine; Alexis Fischer; Azzedine Boudrioua; Abdellaziz Doghmane

Addresses: Faculty of Sciences, Department of Physics, Laboratory of Semiconductors, Badji Mokhtar-Annaba University, BP 12, Annaba 23000, Algeria ' Faculty of Sciences, Department of Physics, Laboratory of Semiconductors, Badji Mokhtar-Annaba University, BP 12, Annaba 23000, Algeria ' Faculty of Sciences, Department of Physics, Laboratory of Semiconductors, Badji Mokhtar-Annaba University, BP 12, Annaba 23000, Algeria ' Faculty of Technology, Laboratory of Environmental Engineering, Béjaia University, Béjaia 06000, Algeria ' Faculty of Sciences, Department of Physics, Laboratory of Crystallography, University of Constantine 1, Constantine 25000, Algeria ' Galilee Institute, Lasers Physics Laboratory, Paris 13 University, Villetaneuse 93430, France ' Galilee Institute, Lasers Physics Laboratory, Paris 13 University, Villetaneuse 93430, France ' Faculty of Sciences, Department of Physics, Laboratory of Semiconductors, Badji Mokhtar-Annaba University, BP 12, Annaba 23000, Algeria

Abstract: In this paper, amorphous and polycrystalline nano-structured TiO₂ thin films were prepared by sol-gel dip-coating process. The effects of different fabrication parameters (e.g., withdrawal speed, annealing temperature) on the structural, morphological and optical properties of the synthesised films were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and UV-visible Spectrophotometry. Waveguiding properties such as propagating modes and optical loss were measured at 632.8 nm by M-lines spectroscopy (MLS). The results indicate that all thin films annealed at 500ºC exhibit XRD patterns and FTIR data consistent with the TiO₂ anatase phase. AFM images have revealed that morphology and surface roughness of deposited thin films depend on withdrawal speed and heat treatment temperature. The UV-visible transmittance results show that all thin films were transparent with an average transmittance higher than 70% in the visible region. The results have also demonstrated from MLS measurements that TiO₂ thin film slab waveguides deposited at withdrawal speed of 2 cm/min and annealed at 500°C exhibit not only better light confinement but also lower optical loss than those dip-coated at the speed of 1 and 3 cm/min.

Keywords: sol-gel; TiO2 thin films; titanium dioxide; X-ray diffraction; optical properties; UV-visible transmittance; M-lines spectroscopy; waveguiding applications; nanotechnology; physical properties; synthesis parameters; morphology; surface roughness; withdrawal speed; heat treatment; temperature.

DOI: 10.1504/IJNT.2015.068879

International Journal of Nanotechnology, 2015 Vol.12 No.8/9, pp.572 - 583

Published online: 17 Apr 2015 *

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