21 % p-type industrial perc cells with homogeneous emitter profile and thermally grown oxidation layer

In recent year, anneal process have been used to reduce the dead layer and higher phosphorous active ratio by separating deposition and drive-in process. In this paper, two process flows are demonstrated on silicon mono-crystalline PERC cells to investigate the improvement with anneal process. Higher minority carrier lifetime and lower emitter saturation current density are shown due to higher active ratio and thermal oxidation layer passivation. Over 0.3% cell efficiency improvement with anneal process due to less recombination in emitter. With suitable front-side silver paste, cell efficiency showed additional 0.2% cell efficiency improvement and 21% in champion cell is achieved due to lower Ag/Si recombination and contact resistance with blanket emitter design.