Optimization of laser scribing for thin-film photovoltaics

In this paper, the authors report on studies of four different lasers for the scribing of thin-film photovoltaic materials including CdTe, CIS, SnO₂, ZnO, and Mo. They have used cw-lamp-pumped and flashlamp-pumped Nd:YAG lasers (λ=532/1064 nm), a copper-vapor laser (511/578 nm), and an XeCl-excimer laser (308 nm), with pulse durations ranging from 180 nsec down to 8 nsec. The purpose of this work is to identify the effects of laser wavelength and laser pulse duration on the most effective energy utilization and on the quality of the scribe line. Ablation spots and scribe lines were examined by optical microscopy and stylus profilometry. The ablation threshold has been identified for the combinations of four lasers and five materials. The energy density for optimum removal of material has been identified for two of the laser systems (three wavelengths)