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Silver crystals at the interface of silver thick film contacts carry the current across such contacts and therefore govern the contact resistance. The crystals grow nearly exclusively in pits in the silicon surface, which form during contact formation before the crystals and hence determine the amount and size of crystals. We simulate the mechanism of pit formation at such contact interfaces by using a model based on the removal probability of silicon surface atoms. The model leads to good agreement between experimentally observed and simulated pits. The results enable the prediction of pit formation in dependence of contact processing parameters

The influence of the doping profile under the metallization for laser doped selective emitter solar cells is investigated. Laser doping allows profile tailoring to some extent by adapting the pulse energy, resulting in Gaussian doping profiles. Numerical calculations using PC1D show that the doping profile influences the recombination at the metal-semiconductor interface. The value J0e,met is used to characterize this influence on solar cell level employing calculations with the 2-diode-model. Selective emitter solar cells have been fabricated to validate, whether this effect can be observed on cell level. IV measurements show a dependence of the open circuit voltage on the profile. This is determined to be partly due to a different 2nd diode recombination current J02 for different doping profiles underneath the contact. The effect of J0e,met is also ascertainable

Nanoscale silver crystals located on the silicon surface at the interface of silver thick film contacts carry the current across the contacts. By quantifying the interface area between the silver crystals and the silicon from scanning electron microscopy images of the silicon surface beneath the contact, we calculate the macroscopic specific contact resistance for contacts of different quality. We find good agreement with experimental contact resistance measurements. The presented results enable the prediction of the macroscopic specific contact resistance from the nanostructure found at the contact interface