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

Available online: 12 Apr 2015 *

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