ABSTRACT
Porous semiconductor materials have been around for many years. Porous Si was first inadvertently produced in 1956 during studies of electrochemical polishing of silicon wafers [1]. Fabrication of porous Si was next reported by Turner [2] in 1958. For some considerable time, when the formation of porous Si was mentioned, it was regarded as a negative side effect, which sometimes accompanied electrochemical etching of Si aimed at developing electropolishing techniques for Si wafers. The situation, however, changed after 1975, when researchers at Nippon Telegraph and Telephone Public Corporation suggested the so-called IPOS process (insulation by porous oxidized silicon) [3], where formation of porous layers in n-Si was playing a key part. However, even until now, the concept of a porous semiconductor is regarded as a phenomenon in semiconductor physics, as the mechanism of porous semiconductor formation is still not clear. Indeed, porous Si is credited with the largest number of attempts to explain the formation of porous structure as a result of anodization (see, e.g., the review by R.L.Smith and S.D.Collins [4]). Yet the fabrication of porous materials based on AIIIBV and AIIBVI semiconductors made it clear that the models developed for Si cannot fully address the general phenomenon of porous semiconductor formation, and new approaches are in demand (for a recent review on porous semiconductors, see, e.g., the paper by Chazalviel et al. [5]).
