Laser Treatment to form An Effective Base Contact in a - Si:H/c-Si Heterojunction Solar Cells

Luca Serenelli, Massimo Izzi, Rosa Chierchia, Mario Tucci
2015 Energy Procedia  
In this paper we investigate the p-type a-Si:H/ia-Si:H/p-type c-Si structure, commonly used as base contact in amorphous/crystalline silicon heterojunction solar cell when fabricated on p-type c-Si wafer. Even though the most effective amorphous silicon/crystalline silicon heterostructure is based on n-type c-Si due to higher bulk lifetime, the p-type c-Si still remains the most common and cheaper substrate for silicon based solar cell. In particular we study the effect of localized 532nm
more » ... calized 532nm pulsed laser treatment at different laser conditions in order to reduce the cell series resistance due to the base contact. In this approach the p-type a-Si:H layer is used as a source of boron dopant. Depending on the thickness of the p-type a-Si:H film, when the laser beam is focused on p-type a-Si:H layer the boron can be transferred into the c-Si base to form an overdoped region and then an effective local Back Surface Field, able to enhance the hole collection at the metal of the base electrode in the p-type c-Si based heterojunction solar cell. The application of a thin Aluminum layer on top of the amorphous silicon to be treated by laser is also concerned. Series resistance of a transverse structure composed by the laser treated p-type a-Si:H/c-Si/opposite surface contacted by InGa is considered to optimize the laser procedure. Values as low as 0.5 cm 2 are obtained when the aluminum layer is adopted.
doi:10.1016/j.egypro.2015.12.318 fatcat:6am6gtesd5alzoqtnk4ys7dtia