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Pore formation in silicon by wet etching using micrometre-sized metal particles as catalysts

“…This phenomenon suggests that part of the positive holes diffused from the bottom of the pores, where Au particles existed, to the sidewalls of the Si sample and formed nanoporous Si layers. Since the nanoporous Si gradually dissolves into the HF solution, [20][21][22] Si is etched more at places where the surface is in contact with the HF solution for a longer time. This results in the formation of pores with conical shapes, as shown in Fig.…”

Thin Porous Silicon Films Displaying a Near-Surface Dip in Porosity

“…Their analysis of the initial response during galvanostatic conditions show characteristic regions in the electrochemical dynamics related to doublelayer formation in the first 30 µs, space charge region formation in the following 100 ms, pore nucleation in the following 3-10 s, depending on current density and HF concentration, and pore etching following that period. Pascual, et al (15) argue that nucleation of pores takes place during the first minutes of the anodization, but is less detectable after the first seconds because after that time pore propagation has also started. Pascual,et al (15) further describe PS growth kinetics with equations similar to those used to describe nucleation and growth of new phases in condensed matter.…”