Photoluminescence Imaging for Photovoltaic Applications

Photoluminescence (PL) imaging is a versatile technique for the characterisation of silicon samples across almost the entire photovoltaic (PV) value chain. Within only a few years after the first demonstration of PL imaging on large-area silicon wafers at the University of New South Wales in 2005, this measurement principle has quickly evolved into a standard method for process monitoring in R&D and is now being used at most PV research institutes and leading wafer and solar cell manufacturers. The first part of this paper provides a brief overview on PL imaging and discusses some specific applications and quantitative analysis methods, including spatially resolved calibrated minority carrier lifetime and series resistance measurements. The high resolution and short measurement time of PL imaging also allow a range of applications for inline process monitoring in production. Emphasis is given in the second part of this paper to PL imaging applications in solar cell manufacturing at an early stage of the PV value chain, specifically the characterisation of silicon bricks and ingots prior to wafer cutting and of as-cut wafers prior to solar cell processing.