Electronic relaxation in PLD TiO2 films processed with femtosecond UV-laser

Modifications of shallow electron trap states near conduction band was analyzed after surface structuring of TiO2 thin films prepared via pulsed laser deposition method. Laser-induced periodic surface structures (LIPSS) were produced on the large-area films after irradiation with femtosecond KrF laser (λ = 248 nm). While spatial period of LIPSS Λ ≈ 190 ± 10 nm was not affected by laser fluence, coherence was increased with an increase of laser dose. Time-resolved microwave conductivity measurements accompanied by theoretical modelling revealed energetic positions of shallow electron trap states, connected to LIPSS. A possibility to alter the trap states energy via surface structuring of the material was shown.