Etching of porous silicon in basic solution

This study reveals that a silicon sample with a porous layer immersed in strong basic solution is etched in several steps according to the surface area of the various materials to be dissolved (nano/macroporous or bulk silicon). As a result it demonstrates the possibility to produce various silicon surface morphologies. These morphologies range from macropore structure to inverted pyramids with crystalline facets. The technique used was the immersion of porous silicon in basic solution and the parameters varied were the immersion time and the concentration of the solution. This is a simple and interesting method to produce a desired morphology of silicon. Furthermore, this work shows the limit of the porosity determination by the weight measurement method.