Low-temperature atomic layer deposition of TiO2 activated by laser annealing: Applications in photocatalysis

This work reports an innovative method to obtain anatase TiO2 films on polymeric substrate. The low temperature atomic layer deposition (LT-ALD) of TiO2 on polymeric substrate was combined with the laser irradiation. TiO2 amorphous films were deposited by LT-ALD on polyethylene naphthalene (PEN) substrate at a temperature of 90 C. Successively, a KrF excimer laser was used for the annealing of the TiO2 films. The laser annealing induced the crystallization of the films in the form of anatase. A detailed morphological, structural, and chemical characterization was performed by ellipsometry, scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). The photocatalytic aptitude of the investigated films was demonstrated by the degradation of the methylene blue (MB) dye in aqueous solution under UV light irradiation. Simulations of the temperature depth profiles as a function of the time during the laser processes were performed. The results demonstrate that the matching of the extremely low temperature growth by ALD with the laser irradiation allows to synthetize anatase TiO2 films on flexible substrate that could find applications in photocatalysis, especially for wastewater remediation.