In order to remove parasitic emitter diffusion around wafer edges of Solar Cells, laser technology is gaining more and more interest. The technique is fast, suitable for inline process, and contactless for safe handling of thin solar cell wafers. We have developed a very efficient process that makes use of high power, high quality single mode laser emitting at 355 nm, resulting in a process as fast as 1.5 s/cell, with isolation efficiency as high as 99% (as mesured by LBIC technque). Furthermore, UV laser radiation, due to the high absorption coefficient, results in a nearly damage free groove structures in Silicon, thus maintaining high solar cells conversion efficiency. We have applied Light Beam Induced Current (LBIC) technique for the in-line detection of wafer edges leakage, which influence the final solar cell quality.Based on the use of a galvanometric x-y scanner system, three amplitude modulated lasers (633 nm, 780 nm and 830 nm) are focalised on the sample surface with a lateral resolution of 60 mm on an area of 12x12 cm2. The pictures shows the LBIC immage of an optimized UV laser isolation process, the parasitic leakage (right end side of the immage) is nearly absent.
Italiano
English