Micro/nano-structures formation on ITO thin film irradiated by different femtosecond laser wavelengths

This study presented the fabrication of micro/nano crystalline indium tin oxide (c-ITO) patterns on glass substrate using a femtosecond laser-induced crystallization followed by chemical etching. In the proposed approach, an amorphous ITO (a-ITO) thin film was transformed into a c-ITO micro/nano structure over a predetermined area using femtosecond laser beam irradiation, under two different wavelengths, 1064 nm and 532 nm, of 1 MHz repetition rate femtosecond fiber laser. The residual a-ITO thin film was removed by an etchant solution, in order to form a uniform c-ITO pattern. The formation was due to the heat accumulation effect provided by the high-repetition rate of the femtosecond laser pulses. When the laser power approached the ablation threshold of the a-ITO thin film, periodic-like c-ITO nanostructures with one-quarter of the irradiation laser wavelength were formed by linearly-polarized laser beam irradiation.