*3.4.3. Laser ablation*

Laser-based front-contact openings and metal deposition are considered to constitute the most appropriate method for fabricating cells with Ni/Cu contacts on the industrial scale. In 1990, laser-based contact patterning was done for EFG polycrystalline silicon solar cells [63]. The laser process was used to fabricate laser-grooved buried contact (LGBC) solar cells at the University of New South Wales (UNSW), Australia [64]. Later on, a BP Solar was involved to produce LGBC solar modules commercially [65].

Laser-based ARC ablation can not only help in patterning the grid more easily with Ni deposition, but can also assist in producing cells with higher efficiencies. Thin-width laser grooves for the LGBC cells and selective emitter doping can be performed with the laser-based process for solar cell applications. Thinner finger lines and selective emitter doping ensure that a high open-circuit voltage (Voc) and higher efficiencies can be realized. Moreover, the heavy diffusion step for selective emitter solar cells can be conducted relatively easily [66, 67]. At Fraunhofer ISE, laser chemical processing (LCP) was demonstrated involving the performance of local etching by the use of phosphorus doping and laser grooving with damage free silicon microstructuring [68]. LCMD and LTC methods were also adopted to pattern the front-contact grid and Ni seed layer deposition simultaneously for solar cell applications [51, 52].
