Quantitative characterization of dry textured surfaces

In the photovoltaic industry light trapping by texturing is an increasing important issue with decreasing crystalline silicon wafer thickness down to 150 µm to further increase solar cell efficiency. In this study plasma texturing starting on as cut mono-crystalline silicon wafers, using the Expanding Thermal Plasma (ETP) technique and the Linear Microwave Plasma (LMP) technique by SF6/O2 chemistry is investigated optically in more detail by means of confocal microscopy and atomic force microscopy (AFM). The results are compared to a standard wet chemical KOH/IPA texturing process, which is anisotropic caused by the dependency of the etch rate on the crystallographic orientation of the wafer and results therefore in a pyramidal texture. An approach for a complete analysis of the created textures is presented including statistical roughness parameters, scatter angle distributions as well as surface reflectances