In-line Monitoring of Electrical Wafer Quality Using Photoluminescence Imaging

Abstract

Solar cell efficiency and related performance data such as the open circuit voltage and the short circuit current are shown to correlate in a predictable fashion with electrical defect metrics that are derived from photoluminescence images taken on as-cut multicrystalline silicon wafers. The electrical defect metrics are obtained by employing proprietary image processing techniques, the output of which can be used to make decisions about wafer supply and cell processing conditions. Photoluminescence imaging inspection systems are introduced that are capable of capturing megapixel images on as-cut wafers with image acquisition and data processing times that are compatible with line speeds in wafer and cell production.