Optimization of Laser Scribing for Thin-Film PV Modules: Annual Technical Progress Report, 12 April 1995 - 11 April 1996

This report covers the first year of a 2-year project to investigate the use of four different types of lasers for scribing materials used for polycrystalline thin-film photovoltaics. The materials under investigation include semiconductors (cadmium telluride and copper indium gallium diselenide), transparent conducting oxides (fluorine-doped tin oxide and aluminum-doped zinc oxide), and a metal(molybdenum). The laser systems are all commercially available and were chosen for the range of pulse durations and wavelengths. In collaboration with Solar Cells, Inc., International Solar Electric Technologies, and C J Lasers, Inc., we used a continuous krypton-lamp-pumped, Q-switched Nd:YAG laser; a flashlamp-pumped Nd:YAG laser; a copper-vapor laser; and a XeCl-excimer laser. The lasersystems and beam focusing options are being evaluated from the pont of view of the efficiency of pulse-energy utilization, potential for high scribing velocity, and scribe quality (e.g., electrical isolation, narrow scribe width, small heat-affected zone, and minimum ejecta rim at the scribe edge).