The porous silicon (PSi) material, an electrochemical derivative of silicon, is a natural nano-structured material that can be prepared easily without much sophistication. The history of PSi research is quite remarkable. This material was accidentally discovered by Ulhir at Bell Labs, USA, in 1956
, followed by Turner
during a study on the electropolishing of silicon in hydrofluoric acid solution. After the discovery, only a small amount of interest in the field developed as a result of the poor understanding of the porous structure. In the 1970’s, it was found that by thermal oxidation the porous structure could be easily transformed into silicon dioxide and used as an isolation dielectric material.
Further advances in electronic isolation technology by Japanese groups in the 1980’s led to the development of full isolated porous oxidized silicon (FIPOS)
and the silicon-on-insulator (SOI)