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Titel:
Qualification of multi-crystalline silicon wafers by optical imaging for industrial use
 
Auteur(s):
 
Gepubliceerd door: Publicatie datum:
ECN Zonne-energie 24-9-2012
 
ECN publicatienummer: Publicatie type:
ECN-M--12-047 Conferentiebijdrage
 
Aantal pagina's: Volledige tekst:
5 Download PDF  (447kB)

Samenvatting:
We have developed a method to qualify multi-crystalline silicon (mc-Si) wafers that are being used in a production process. An optical image of an etched wafer is made. This etching can be a standard industrial acid etching for mc-Si wafers as is commonly used for saw damage removal and simultaneous iso-texturing. Digital image processing is then applied to identify the number of dislocations and their distribution over the wafer. This information is used as input for a cell performance prediction model, where the performance is characterized by the open circuit voltage (Voc) or the efficiency. The model can include various levels of sophistication, i.e. from using an average density of dislocations to the full spatial resolution of the dislocations in a 2D simulation that includes also the metallization pattern on the cell. The predicted performance is then evaluated against pre-selected criteria. The possibility to apply this optical qualification method in an initial stage in the production enables early rejection of the wafers, further tailoring of the cell production process or identification of instabilities in the production process.


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