Light-emitting porous silicon formed by photoetching in aqueous HF/KIO₃solution

The formation of light-emitting porous silicon (PSi) in a HF solution by adding an oxidizing agent KIO 3 is presented. The PSi layers are formed by photoetching under Xe lamp illumination. The use of a Xe lamp enables the formation of large PSi layers on n-Si substrates. Yellow photoluminescence peaking at ∼2.0 eV is observed for the sample prepared in a HF/KIO 3 solution for 6 min, which is about 80 times stronger than that formed in a pure HF solution for 105 min. The surface topography as characterized by atomic force microscopy reveals features of the order of 20–100 nm. The PSi formation mechanism can be successfully explained with the aid of a surface energy-band diagram of n-Si in the HF/KIO 3 electrolyte.