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Combined thin-film thickness measurement and surface metrology of photovoltaic thin films using Coherence Correlation Interferometry

Accurate measurement of the thickness of transparent and semi-transparent thin films is important in all thin film photovoltaic technologies. Surface roughness measurements are also important to interpret the performance of photovoltaic devices. Here we report on a new capability for coherence correlation interferometry that enables it to provide thin film thickness measurements with comparable accuracy to spectroscopic ellipsometry as well as measuring surface roughness with sub-nanometre precision. Applications of the technique's new capability for thin film thickness measurements are presented for a range of photovoltaic materials. In particular, we report on the close correlation between results obtained by coherence correlation interferometry and spectroscopic ellipsometry. Coherence Correlation Interferometry is a fast, sensitive, non-contacting, non-destructive metrology technique with the potential for use as an in-line quality assurance tool in the large scale production of photovoltaic modules.