Optical Characterisation of Random Pyramid Texturization

The reflection property of alkaline textured wafers is an important parameter for texture evaluation. Nevertheless, the geometric properties of the surface structure influence cell performance and cannot be distinguished by reflection measurements only. The pyramid size distribution can affect, e.g. contact formation or emitter passivation. Confocal images allow the recognition of shiny areas, the pyramid number and pyramid size distribution. The laser intensity and height information images were evaluated by image processing techniques. The pyramid segments of the pyramids were found to be a good indicator for peak size and recognition of long pyramid edges. The derived pyramid height distribution can be used to distinguish different pyramid homogeneity.