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Fast Measurements of Effective Optical Reflectivity Using a Conventional Flatbed Scanner
L. Korte, S. Bastide, C. Lévy-Clément
Light Trapping, Oblique Incident Sunlight, Qualification and Testing
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Mono- and Multicrystalline Silicon Cells and Materials, Processing Technology of
Event: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain
Session: 2CV.4.33
1431 - 1436
ISBN: 3-936338-24-8
Paper DOI: 10.4229/23rdEUPVSEC2008-2CV.4.33
0,00 EUR
Document(s): paper


The use of a conventional flatbed scanner as a means to assess the optical properties of multicrystalline silicon wafers after texturization has been explored. It was found that it is necessary to i) introduce an additional diffusor between the wafer under test and the scanner’s document glass, and b) to obtain scans in four perpendicular directions of the wafer. Averaging over the four scans gives a reflectivity map with a resolution of ~ 0.1x0.1 mm². It is shown that the map can be calibrated to yield a spatially resolved image of the effective reflectivity of the wafer, with an accuracy of about 1%. Furthermore, the difference image of two scans in different directions contains additional information on the directional dependence of reflectivity. It is envisaged that in combination with etching procedures that are selective to grain orientation, the information contained in the difference images can be used to obtain grain orientation maps similar to electron backscatter diffraction (EBSD) pictures. Acquisition and processing times of the images are below one minute, and equipment cost a few 100 €, making the technique suitable both for rapid prototyping in the lab and for process control in production.