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Titel:
Contact optimisation on lowly doped emitters using the Corescan on non-uniform emitter cells
 
Auteur(s):
 
Gepubliceerd door: Publicatie datum:
ECN Zonne-energie 1-6-2004
 
ECN publicatienummer: Publicatie type:
ECN-RX--04-059 Conferentiebijdrage
 
Aantal pagina's: Volledige tekst:
4 Download PDF  (580kB)

Gepresenteerd op: 19th European Photovoltaic Solar Energy Conference and Exhibition, Paris, France, 7-11 juni 2004.

Samenvatting:

A method is presented to find with one cell the maximum emitter sheet resistance that can be contacted for a given combination of paste and firing conditions. Cells with non-uniform emitter are made and both emitter sheet resistance and contact resistance are scanned. Plotting the local contact resistance against the local emitter sheet resistance enables the determination of the maximum sheet resistance with good contact. The sheet resistance is mapped with a scanning four point probe, the contact resistance with the Corescan. Non-uniform emitters were created using the side heater in the diffusion belt furnace, in addition some non-uniform emitters were used from experiments in a POCl3 diffusion furnace. One combination of paste and firing conditions was used for all cells, the threshold sheet resistance was found to be 70 W for Cz-Si and > 85 W for mc-Si. The difference may be due to a difference in the acid etch recipe for saw damage removal, leading to a different distribution of crystal planes at the surface. For the POCl3 cells, a threshold of around 60 W was found; above this value, the contact resistance increases much stronger than for the belt furnace cells.


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