The analysis of thin film solar cells can be successfully performed with Micro-XRF. It is possible to measure the structures both in air and under vacuum. The absorption in air for the lowest energies of interest is aceptable. Thus this method can be comfortably used for in-line control during the production process as well as for final testing. Quantification can be done standardlessly. Comparisons with EDS and with WDXRF show good agreement regarding the composition of layers. For EDS quantification results depend on the element lines used. For all these methods the results for layer thickness are in very good agreement.
The analyses in this application example were performed with the Bruker instruments M1 MISTRAL and M4 TORNADO. Both instruments are Micro-XRF spectrometers but use different measurement conditions. The M1 MISTRAL can only measure in air and uses collimators which limit spot sizes to 300 μm. The M4 TORNADO can also measure in vacuum and produces spot sizes down to 25 μm using poly-capillary X-ray optics.