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Title:
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Contact optimisation on lowly doped emitters using the Corescan on non-uniform emitter cells
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Author(s):
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Published by:
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Publication date:
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ECN
Solar Energy
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1-6-2004
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ECN report number:
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Document type:
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ECN-RX--04-059
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Conference Paper
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Number of pages:
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Full text:
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4
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Download PDF
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Presented at: 19th European Photovoltaic Solar Energy Conference and Exhibition, Paris, France, 7-11 juni 2004.
Abstract:
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 POCl
3 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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