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2009
Conference Paper
Titel
Comparing luminescence imaging with illuminated lock-in thermography and carrier density imaging for inline inspection of silicon solar cells
Abstract
Electroluminescence (EL) and Photoluminescence (PL) imaging have in recent years been gradually improved and are now important measurement techniques for the characterization of silicon solar cells. The contactless PL is applicable throughout the whole production process, including the characterization of as-cut wafers. In this paper we will demonstrate the application of EL and PL as tools for quality control and compare it with reference techniques like Illuminated Lock-in Thermography and Carrier Density Imaging. The focus of this paper is on the characterization of multicrystalline silicon wafers on an inline-compatible timescale. We find that effective lifetimes measured during processing do not scale with the open circuit voltage of the cell. PL images taken on as-cut wafers already reveal defects from crystallization which limit the cell efficiency. In particular, crystal defects, e.g. dislocations have a significant influence on the open circuit voltage of a solar cell. Thus, by recognizing these features, an electric rating for the wafers can be done before production.