Nanosecond laser-induced damage of transparent conducting ITO film at 1064 nm

Transparent conducting films with superior laser damage performance have drawn intense interests toward optoelectronic applications under high energy density environment. In order to make optoelectronic applications with high laser damage performance, a fundamental understanding of damage mechanisms of conducting films is crucial. In this study, we performed laser damage experiments on tin-doped indium oxide films (ITO, Bandgap = 4.0 eV) using a nanosecond (ns) pulse laser (1064 nm) and investigated the underlying physical damage mechanisms. Single ns laser pulse irradiation on ITO films resulted in common thermal degradation features such as melting and evaporation although the laser photon energy (1.03 eV, 1064 nm) was smaller than the bandgap. Dominant laser energy absorption of the ITO film is attributed to free carriers due to degenerate doping. Upon multi-pulse irradiation on the film, damage initiation and growth were observed at lower laser fluences, where no apparent damage was formed upon single pulse, suggesting a laser-induced incubation effect.