A simple laser based process for the formation of a LBSF for n-type silicon solar cells

We present a simple laser process for the formation of a local back surface field (LBSF) for n-type silicon solar cells. Point contacts are formed by applying a laser process to a doped, passivating layer of amorphous silicon carbide (PassDop layer). In a single processing step, point contacts are opened and local doping of the underlying silicon is done. A variation in dopant content and laser fluency enables the control of the doping profile. The effectiveness of the LBSF structure is investigated on lifetime samples. We find that high dopant content of the PassDop layer and medium laser fluencies yield best values for the suppression of the recombination at the contact.