Semiconductor Physics, Quantum Electronics & Optoelectronics, 29 (3), P. 292-301 (2026).
DOI: https://doi.org/10.15407/spqeo29.03.292

Femtosecond laser processing of titanium dioxide films prepared with sol-gel method

I.M. Dmytruk¹, N.I. Berezovska¹, P.A. Manoryk², N.I. Romanovska², G.P. Podust¹, Ye.S. Hrabovskyi¹, P.S. Khort¹, O.S. Kondratenko³, V.R. Romanyuk³, S.V. Mamykin³

¹Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska street, 01601 Kyiv, Ukraine
²L.V. Pisarzhevsky Institute of Physical Chemistry, National Academy of Sciences of Ukraine,
31, prospect Nauky, 03028 Kyiv, Ukraine
³V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine,
41, prospect Nauky, 03680 Kyiv, Ukraine
^*Correspondence author e-mail: nataliya.berezovska@knu.ua

Abstract. The self-cleaning and photocatalytic properties of TiO₂ films are crucial for coating of optical elements that operate in harsh environmental conditions. During our research, the optimal chemical composition of the sol-gel mixture and conditions for spin-coating of TiO₂ films were selected. Ellipsometry studies showed that before calcination at 450 °C, the TiO₂ film on glass had a thickness of 247 nm and was quite porous with significant roughness. After calcination, the thickness of the TiO₂ film decreased to 89 nm. It became significantly denser. Further modification of TiO₂ films was performed using femtosecond laser pulses with a wavelength of 800 nm. Treatment of TiO₂ films with laser radiation resulted in the formation of laser-induced surface features, including nanoparticles and nano-cracks. The selected laser processing conditions were aimed to maintain sufficient transparency of the TiO₂ film that was achieved at the density of irradiation pulse energy of 0.025 J/cm². The laser-treated surface exhibits improved hydrophilic properties. The optical properties of TiO₂ films on glass, studied using photoluminescence and Raman scattering, showed that after post-synthetic processing, including femtosecond laser treatment, a predominantly anatase crystal structure was formed.

Keywords: titanium dioxide, thin film, sol-gel method, femtosecond laser pulses, laser-induced surface structures, photoluminescence, Raman scattering.