Precision testing and analysis methods are a great advantage in the research and development of materials, cells, modules and systems suitable for photovoltaics. The availability of the best methods for measuring, characterising, testing and standardising them is in fact crucial to the success of research and development projects. Many materials, especially silicon and most semiconductors, are transparent to terahertz radiation. As a result, layer thicknesses and material parameters such as conductivity or carrier life time can be analysed more easily and accurately with terahertz radiation. A fundamental research project to be carried out in cooperation of CTR Carinthian Tech Reserach with Vienna University of Technology will explore test processes to evaluate the potential of terahertz radiation in characterising photovoltaic substrates.
The figure above shows measurements of the carrier life time for two monocrystalline silicon wafers. It enables the results of terahertz spectroscopy (right) to be compared with those of microwave photoconductive decay (MWPCD) measurement (left). Areas of short carrier life time are coloured red and detected by both the measurement methods. In addition, terahertz (THz) tomography also provides the opportunity to examine the wafer’s layer structure.
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