Characterization of electroless nickel plating on silicon solar cells for the front side metallization

The selective deposition of nickel on silicon wafers from an electroless bath is a very attractive process for the front side metallization of silicon solar cells. The anti-reflection coating (ARC) at the front side of the wafers is used as a mask for the deposition. Nickel is plated from an alkaline nickel sulfate bath with sodium hypophosphite as a reducing agent and ammonia for pH control. Characterization of the deposition depending on bath conditions, substrate doping and light application will be presented in this paper. Silicon solar cells with SiO2 and SiNx as ARC have been processed featuring dielectric passivation and Laser Fired Contacts (LFC) at the back side. Efficiencies up to 18.9% have been achieved using this technology. The samples have been characterized by SEM and measurement of the IV curves.