Relevant pinhole characterisation methods for dielectric layers for silicon solar cells

A wide range of dielectrics are used for photovoltaic (PV) applications (anti-reflection, passivation, insulation and masking layers) usually applied on large surfaces often presenting a texture or an important roughness. The application range of such a layer can heavily suffer from uncontrolled pinhole density. Therefore four pinhole characterization techniques have been compared regarding their relevance for current PV dielectric characterization. Two of these techniques present a good potential for the qualitative and quantitative pinhole characterization of especially for PV dielectric, on flat and rough surfaces. As a test for the characterization method an evaluation of the impact of aluminum evaporation on thick PECVD SiOx pinhole density has been performed. This shows the ability of the characterization technique developed in this paper to perform quantitative pinhole characterization.