Identification and characterization of performance limiting regions in poly-Si wafers used for PV cells

This study demonstrates the usefulness of combining multiple techniques to analyze performance-limiting regions in the poly-Si wafers that are used for photovoltaic (PV) cells. This is done by first identifying performance-limiting regions using macroscale techniques including photoluminescence (PL) imaging, microwave photoconductive decay, and reflectometry), then using smaller-scale techniques such as scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), cathodoluminescence (CL), and transmission electron microscopy (TEM) to understand the nature of such regions. This analysis shows that structural defects as well as metallic impurities are present in performance limiting regions, which together act to decrease conversion efficiencies in poly-Si PV cells.