EXCESS CURRENTS IN HIGH EFFICIENCY Si SOLAR CELLS.

Silicon N/P junction solar cells have now reached efficiency levels which range from 17% to 19%. Some are the violet-type cell having textured surface, multiple A/R coatings, or back surface fields. Some have surface passivation in the form of an oxide between grid lines to improve ultraviolet response. Others are of the MINP variety in which a 20 - 25 angstrom oxide grown over the entire ion implanted N-region reduces surface recombination. The top metal grid is composed of a low work function metal rather than the typical Ti/Pd/Ag contact. Excess current mechanisms for the MINP cell and the passivated violet-type cell (N/P-P) are compared. These currents must be identified since they limit solar cell efficiency.