Optimization of Laser Scribing for Thin-Film PV Modules: Final Technical Progress Report, 12 April 1995 - 11 October 1997

This report covers the work done by the University of Toledo under this subcontract. Researchers determined the threshold power densities for the onset of ablation from thin films of CdTe, CuInSe2, SnO2:F, ZnO:Al, gold, and molybdenum for 12 different wavelength laser systems using wide variations of laser pulse durations. Optimum energy density for the most efficient removal of material duringscribing strongly depends on the wavelength of the laser and, to a smaller extent, on the pulse duration. The optimum energy densities range from 0.5 J/cm2 for the 532-nm, 8-nsec YAG pulse on CdTe to 0.2J/cm2 for the excimer laser at 308 nm on CIS. Poor scribing of CdTe was seen with the 1064-nm beam; ZnO was scribed poorly by all lasers except for the excimer laser. Excellent scribe profileswere observed with the 308-nm excimer lasers on all materials, including ZnO.