| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 77645 | Solar Energy Materials and Solar Cells | 2016 | 8 Pages |
•We examine the impact of metal spikes on B-emitters on metal contact recombination.•A three dimensional model with the QSSPC technique is used for simulation.•Shallow spikes have minor effect on j0,met, deep spikes increase j0,met abruptly.•Spikes should not penetrate a critical zone starting 150 nm above the pn-junction.•Deeper profiles are more robust against deep spikes, as samples confirm.
With this work, we introduce numeric three-dimensional simulation of metal spiking into highly boron-doped surfaces of n-type silicon solar cells, which is moreover performed with a simulation of the quasi-steady-state photoconductance technique. This setup serves as a virtual experiment to simulate the dark saturation current density j0,met of metallized boron-doped emitters with respect to metal spikes originating from the silver–aluminum (Ag–Al) contact. With the results obtained from this simulation model we approach quality and quantity of increased j0,met and give detailed insight to which degree a solar cell’s performance is possibly harmed by this effect. We show that metal spikes penetrating into boron-doped emitters are of harmless nature concerning j0,met until their tips reach depths where boron doping concentration is lower than approximately 1018 cm−3. Deeper spikes then lead to an exponential increase in j0,met as more and more carriers from emitter and also the base are able to diffuse to its tip and recombine there. With the help of j0-results obtained experimentally in combination with the simulation results, we discuss the influence of spikes on emitter recombination, the benefits that can be achieved with deeper emitter doping profiles, and suggestions for the further development of pastes to contact boron-doped surfaces.
