New porous silicon formation technology using internal current generation with galvanic elements

Silicon Porosification: State of the Art

“…It is the same effect as in different current densities utilized by anodization. 269 This metallization is performed by various techniques such as sputtering, thermal evaporation, electrochemical deposition, or electroless deposition in HF solutions.…”

“…Thus, pores ranging form mesopores to macropores could be obtained. Ashruf et al 259 and Splinter et al 269 believe that the main advantage of this porous formation technique is that a special sample holder to contact the Si is not required. The process of anodization is easy to handle; it has no etching cell and needs an external current source.…”

Silicon Nanocrystals in Porous Silicon and Applications

“…It offers reasonably high etch rates. For example, for p þ -type Si, an etch rate of about 9 mm/min was shown [17]. PSi obtained by this method can show good lateral and in-depth uniformity.…”

“…When the solution is in contact with air, oxygen is the natural oxidizing agent. Other oxidizing agents, in particular peroxodisulfate [14] and hydrogen peroxide [14,17], may be added to enhance the etch rate.…”

Fabrication and chemical surface modification of mesoporous silicon for biomedical applications

“…The current could be obtained, for example, using Si-wafers with a backside deposited Pt/Au layer, which is immersed in an HF based electrolyte. The internal current leads to a similar etching process as in electrochemical anodization, and quite thick (>10 m) PSi layers could be produced with the method [18,19].…”