Polarisation analysis of luminescence for the characterisation of defects in silicon wafer solar cells

Abstract

Photoluminescence and electroluminescence imaging has progressed significantly in recent years and is now routinely used to extract spatially resolved characteristics of silicon wafer solar cells and other electronic devices. In this paper, we report on the expansion of the luminescence imaging technique by the application of spatially resolved polarisation analysis. Luminescence imaging of silicon wafer solar cells is extended to yield the partial polarisation of luminescence. It is hypothesised, and then shown experimentally, that certain defects in silicon wafer solar cells generate strongly polarised electroluminescence. In particular, extended crystalline defects in silicon wafers are shown to exhibit a partial polarisation of electroluminescence as high as 60%. The linear polarisation is found to be oriented to the dislocations in the multicrystalline silicon wafer solar cells. The luminescence polarisation effect is discussed in relation to internal charge anisotropy of defects in silicon wafer solar cells. These results may be used to advance the characterisation of solar cells, to understand the electrical properties of defects in silicon wafer solar cells, to study the formation of defects during crystal growth, or to probe the Bloch band anisotropy at regions of a high dislocation density. Copyright © 2011 John Wiley & Sons, Ltd.