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Title:
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Local carrier lifetime of non-passivated multi-crystallinesilicon wafers measured by the MFCA method
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Author(s):
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Published by:
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Publication date:
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ECN
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1995
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ECN report number:
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Document type:
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ECN-RX--95-060
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Other
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Number of pages:
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Full text:
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6
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Download PDF
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Abstract:
Contactless measurement techniques of excess carrier recombinationbehaviour in semiconductors are well known. The methods were applied to
characterise multi-crystalline silicon ingots or multi-crystalline wafers
with passivated surfaces. In the first case the material is thick enough to
neglect the influence of the surfaces, in the second case the surfaces can be
ignored because they are passivated. In this paper we will show that the
Modulated Free Carrier Absorption (MFCA) method can be used to measure the
local bulk lifetime of as-cut wafers without surface passivation techniques.
The wafer can be characterised directly at the input of a solar cell
manufacturing process without any treatments as for example a thermal oxide
passivation technique, which might alter the excess carrier recombination in
the bulk because of the temperature. Certainly this technique cannot be
applied in all cases, but by an uncertainty analysis it is shown that it
yields valuable information in most cases that are relevant to
multi-crystalline solar cell production. By different examples the results of
this characterisation technique are shown and a correlation between mean
carrier lifetime in the as-cut wafer and the final solar cell parameters is
demonstrated. 7 figs., 11 refs.
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