Laser Direct Writing of Crystallized TiO2 by Photothermal Effect Induced by Gold Nanoparticles

Near-infrared (NIR) laser annealing is successfully used to crystallize TiO2 thin films from a sol-gel solution deposited on gold nanoparticle arrays (AuNPs). The AuNPs are used as nano-heaters allowing a local temperature increase up to 500 degrees C in the film. The temperature reached under the laser is deduced from the presence of the anatase phase in the samples obtained by laser exposure, showing that crystallized TiO2 can be obtained by the photothermal effect. Different analytical techniques supported this study, such as grazing X-ray diffraction (GIXRD), UV-vis, and Raman spectroscopy. The temperature increase is confirmed by a numerical model that emphasizes the role of NPs coupling in the photothermal effect. Direct laser patterning by NIR laser and in combination with Deep-UV photolithography (DUV) are demonstrated. This fabrication method opens new perspectives in applications such as photonics, photocatalysis, or biosensing.

Automated summary

This study successfully crystallizes TiO2 thin films from a sol-gel solution using near-infrared laser annealing, with gold nanoparticle arrays as nano-heaters. The presence of the anatase phase confirms the temperature increase achieved by the laser, and different analytical techniques support the findings. A numerical model highlights the role of nanoparticle coupling in the photothermal effect. Direct laser patterning and photolithography techniques are demonstrated. This fabrication method has promising applications in photonics, photocatalysis, and biosensing.