Silicon nanostructures from electroless electrochemical etching

Recent advances in the production of Si nanostructures from electroless etching are reviewed, including stain etching, metal-assisted etching and chemical vapour etching. A brief review of the explosion in applications of porous silicon over the past 18 months is also given. The stain film that results from the etching of (poly- or single-)crystalline Si is composed of a porous network of nanocrystalline silicon. Few mechanistic studies of electroless etching have been performed, but the more extensively studied anodic etching of silicon in fluoride solutions provides many clues as to how porous films are formed. Intriguing recent results have shown that control over the properties of the film can be obtained by exercising control over the composition of the etchant.