I'm working on the defects control in mc-Si during process fabrication of the solar cell, using in particular gettering technique. So, I find your project interesting. Please Dr Schmidt, could you inform us on the main aims of your project ? Thank you in advance, - Nabil
Dear Nabil,
Yes i know that you intend Jan, but allow me to render this comment: The control of the defects at the grain boundaries was and still an an interesting research topic. Grain boundaries affect the carrier transport in two ways: They reduce the mobility of the charge carriers across them such that that if their number is large they can control the resistance of the material rather than the bulk scattering and the defects in them can act as recombination centers for the minority carriers reducing their life time. Multi crystalline material have columnar structures such that the grain boundaries lie parallel to flow of the majority carriers and therefore they will scatter them from the side only.
It remains to passivate the crystallographic defects at the grain boundaries by preferential oxidation or hydrogenation or preferential doping.
One of the main serious sources of activating the crystallogarhic defects are the heavy metal atoms which are normally fast diffuser especially along grain boundaries. So, basically one has to take care of heavy metals as they are lifetime killers. In the old literature you can find good work in this issue.
Best wishes
Thanks Dr Schmidt, please let me know if you're also working on the simulation of defects in silicon based solar cells or not, especially the part concerning the behavior of metallic impureties and their complexe during high-temperature processes, like POCl3 emitter formation and co-firing. Regards, - Nabil
Dear Dr Abdelhalim, yes you're right; multicrystalline silicon is a complicated material particularly when one want to investigate the reaction of minority carrier with all the kind of defects existing inside material. the complexity will become biger when one try to combine all these with the fabrication process conditions and steps. Regards, -Nabil
Dear Dr. Schmidt, thank you for your explanation. Personally I find your activities very interesting.
I inform you that I have already worked on the effect of gettering, during emitter formation and co-firing, on the performance of mc-Si based solar cells. In this context, I developed a software that simulates the phosphorus diffusion gettering of some 3d metals such as Cr, Fe and Ni. This software has the flexibility to simulate a multi-plataux PDG in the bulk as well as in the diffused region n+.
Because mc-Si contains several types of defects (other than metals such as B-O complexes), I wanted to start the simulation (with experimental validations) of the reaction between the different defects and their responses to gettering.
The main goal of this work is the control of these defects during the manufacturing process of solar cells and therefore the improvement of their efficiency.
I would be very happy to read your new publications!
Best regards, -Nabil
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