Review on screen printed metallization on p-type silicon

Advanced solar cell contacts feature local contacts to p- and p+- Si. In this review existing models for contact formation to p and p+-Si are presented.The formation of the local Al BSF as applied in PERC like solar cell structures is inhibited by the formation of voids. It is shown that the formation of voids depends on process parameters and their influence on the contact formation is reviewed. Using an analytical model it is possible to predict the depth of the resulting Al BSF in dependence of the contact geometry and the peak firing temperature.Contact formation to B doped Si with pure Ag paste results in high contact resistances whilst contact formation to Al doped Si with Ag paste is less difficult. The contact formation with Ag paste to B doped Si is enhanced by the addition of Al to the Ag paste.