Micro characterization of laser structured solar cells with plated Ni-Ag contacts

An evolutionary approach to increase the cell efficiency of the industrially widely used Al-BSF Si solar cell design is the implementation of a lightly doped emitter and plated Ni-Ag front side contacts. This work shows that this approach can give a significant advantage to fully screen printed solar cells with cell efficiencies up to 19%. However, the adhesion of the plated contacts strongly depends on the tempering induced silicidation of the Ni layer. The application of macroscopic and microscopic characterization techniques indicates that the tempering induces local non-ohmic shunts due to a silicide spiking in the space charge region. The application of an additional selective emitter doping in this experiment could decrease the shunting probability but could not prevent it completely due to inhomogeneous doping depths on the textured surface.