Morphology-driven parameters of engineered functional surfaces

The feasibility of correlating morphology to functional properties of engineered surfaces is today an issue in the characterization of surface features on large-area substrates to enable quality control in highly-parallel manufacturing. The study aims at investigating traceable parameters for determining the relationship between texture, form, sizes and resistance features of functional surfaces, e.g., printed electrodes on c-Si PV cells of standard design and test structure on a ceramic substrate. Test samples with electrodes of various sizes suitable to test surface features in a wide measurement range have been characterized by optical-confocal profilometry and by resistance measurements with dense data sampling. A significant correlation between cross-section-based calculated resistance from 3D topography measurements and local resistance measurements of fingers has been demonstrated either for PV cell and test structure. A roughness scaling of 0,7 with ceramic cell and of about 1 with c-Si cell has been determined from length-scale and log-log plots of Rq top roughness of surface finger. Fractal parameter of top finger profiles of test structure on ceramic substrate and of c-Si cell with standard design is of about 1,5.