Light as a Controlling Tool: White Light Interferometry in Quality Assurance of Photovoltaic Samples

The photovoltaic industry is characterized by a permanent, substantial growing during the last years. Today improving efficiencies and reduction of manufacturing cost of solar cells is essential for the success in the competitive market. The reduction of manufacturing costs is associated with high volume manufacturing of the solar cells by perpetuation of high quality standards and requirements for small tolerances. Measurements of the topography of solar cells now start to play an important role in the quality assurance of the manufacturing process. It allows the three‐dimensional mapping of a complete area with subsequent parameter extraction: so the efficiency of a solar cell depends on the wafer structure: Perfect smooth surfaces absorb less photons than surfaces with a certain, optimized roughness, whereas protecting layers should be as smooth and flat as possible. Similar to all Microsystems the structures can be investigated and compared to the target values: examples are layer thickness, widths and depths of structured lines, the volume‐determination of hollows, defects, pores or abrasion/deposition rates. It also encompasses the 3D profile of printed circuit board tracks or special structures for sophisticated high efficiency photovoltaic elements.