On black solar cells or the tetrahedral texturing of a silicon surface

High-efficiency silicon solar cells have been reported that use a surface alteration to reduce reflection. The process here reported purposely alters the cell surface with an anistropic etching in ternary mixtures of KOH, H2O, and ethyl glycol. Wafers were "sensitized" with a carbon compound to insure etching uniformity. It is suggested that the organic compound creates SiC nucleation sites, which in turn facilitates the formation of a tetrahedral structure on the cell surface. This structure promotes multiple interaction of the light beam between millions of pyramids per square centimeter on the surface. The surface geometry increases the light absorption and reduces reflectivity, thus increasing the cell efficiency.