Growth of ferroelectric Ba_0.8Sr_0.2TiO₃ epitaxial films by ultraviolet pulsed laser irradiation of chemical solution derived precursor layers

Highly crystalline epitaxial Ba_0.8Sr_0.2TiO₃ (BST) thin-films are grown on (001)-oriented LaNiO₃-buffered LaAlO₃ substrates by pulsed laser irradiation of solution derived barium-zirconium-titanium precursor layers using a UV Nd:YAG laser source at atmospheric conditions. The structural analyses of the obtained films, studied by X-ray diffractometry and transmission electron microscopy, demonstrate that laser processing allows the growth of tens of nm-thick BST epitaxial films with crystalline structure similar to that of films obtained through conventional thermal annealing methods. However, the fast pulsed nature of the laser employed leads to crystallization kinetic evolution orders of magnitude faster than in thermal treatments. The combination of specific photothermal and photochemical mechanisms is the main responsible for the ultrafast epitaxial laser-induced crystallization. Piezoresponse microscopy measurements demonstrate equivalent ferroelectric behavior in laser and thermally annealed films, being the piezoelectric constant ∼25 pm V⁻¹.