Self-assembled growth and green emission of gold nanowhiskers

Unique structured Au nanowhiskers were fabricated via electroless metal deposition on Si wafer in KAuCl4–HF solution. A self-assembled localized microscopic electrochemical cell model and a diffusion-limited aggregation process are associated with the formation of Au nanowhiskers. A green photoluminescence (PL) band was recorded. Spectral analyses suggest the green PL arises from the radiative recombination of sp-band electrons with d-band holes in the Au nanowhiskers and its intensity enhancement is due to local electric field connected with the Au particle plasmons oscillation. A red PL band was also observed from long-time etched Si substrates and proposed to be related to Si nanocrystals in the surface layer of etched Si wafer. Its stability was considered to be owing to the formation of stable Si–Au bonds on the surfaces of Si nanocrystals.