Reflectivity of an etched silicon surface with pyramids: II. Experimental results from different etching conditions

An etched silicon (1 1 1) surface is developed for pyramids of different heights, which were obtained from anisotropic etchings of single-crystal silicon wafers under different etching temperatures or etchant concentrations. Experimental results of reflectivity are obtained from an optical test performed on an optical system, including an integration sphere and a photo detector. At relatively lower etching temperatures, the number of pyramids becomes fewer, and size and height vary within a relatively smaller range. In addition, reflectivity is lowered by increasing the etching temperature. The effect of increasing the etchant concentration is very similar to that of increasing the etching temperature. Under a change in the etching temperature, the range of the total reflectivity variations is enlarged by increasing etchant concentration.