Laser cutting thin films for solar panels

The thin films used in the fabrication of solar panels can all be cut using lasers. Narrow tracks must be cut in order to section the films to create cells which are linked in series to generate a useful voltage from a single-sheet solar panel. Ideal tracks should be as narrow as possible to maximize the fill factor, yet still able to ensure a high electrical impedance across the cut. Each cut should not damage the underlying thin film. Track widths of the order of 15 /spl mu/m have been cut in ITO (transparent tin oxide), amorphous silicon and aluminium, and various anti-reflection layers. For the cutting process, which is extremely fast and therefore highly cost effective, the optimum laser wavelength depends upon the film itself. Machines have been constructed which use 1.06 /spl mu/m and 503 nm Nd:YAG wavelengths and 248 nm excimer laser wavelength.