Influence of doping elements on the formation rate of silicon nanowires by silver-assisted chemical etching

Abstract Metal-assisted chemical etching (MACE) has gained great interest for the preparation of vertically aligned silicon nanowires (SiNWs); however, the process mechanism has not yet been identified. In this study, the influence of doping elements on the formation rate of SiNWs prepared by silver-assisted chemical etching was investigated. Two n-type silicon substrates, bulk silicon and silicon-on-insulator (SOI) samples, containing different dopant concentrations (from 1011 to 1019 atoms cm- 3) and species (phosphorous and arsenic), were considered. The SiNW formation rates increase with dopant concentration and are influenced by the dopant species. The use of {SOI} samples allowed highlighting the remarkable loss of the starting device layer in conventional process conditions, never previously observed; such occurrence limits the most achievable SiNW length. The study of the gas evolution both from bulk and {SOI} samples allowed for the first time the in situ {H2} detection as well as to identify one definite overall process reaction.