News Article
Laytec get the thumbs up from German module manufacturer
Measurement time of 0.1 s gives improved accuracy in high volume production
To improve the production process of Cu(In,Ga)Se2 thin film modules, it is essential to ensure the quality of the absorber.
LayTec"˜s spectroscopic photoluminescence (PL) system PearL has been evaluated by the German solar equipment and module manufacturer Manz CIGS Technology GmbH. Measurements on more than 2000 production and test modules proved that PearL performed well under production conditions:
"¢ reliable CIGS characterization across the full module length at different points
"¢ spatially resolved information about band gap, material composition and quality of the CIGS absorber material
"¢ absorber parameters are reported directly after its deposition without interference of other layers
"¢ faulty substrates are identified before the cost-intensive back-end processing
"¢ the measurement time of PearL is only 0.1 s, which makes the tool much more appropriate for high volume production than X-ray fluorescence
To monitor the CIGS coating process and to optimize the module performance, an exact identification of Ga/(Ga+In) ratio (GGI) is of high importance. Since the GGI is directly correlated to the band gap of the absorber, this parameter has an influence on the open circuit voltage Voc and external quantum efficiency EQE(λ) of the device. line scan across the length of a CIGS coated substrate was performed by both PearL and XRF. With the XRF method, the element composition of the absorber is determined and the GGI can be computed. The agreement of both measurement methods to determine the Ga/In ratio is very good (see Fig. 2), which proves that the spectrally resolved PL is a reliable and fast method to obtain in-line GGI line scans.
These results were presented by Manz and LayTec at the last EUPVSEC conference
Fig. 1: Three measurement heads of PearL installed over a module.
Fig. 2: Direct comparison of the GGI results measured by XRF (blue) and PearL (red) across a substrate.
