抄録
Locally selective formation of gold nanostructures on a silicon wafer without photolithography, electrolysis, or hydrofluoric acid was reported previously. With our previous method, gold nanostructures grow selectively on the locally amorphized surface on a silicon wafer when the silicon wafer is exposed to a customized Au ion-containing solution. The locally amorphized surface is produced by, for example, irradiation of a focused ion beam (FIB) or a femtosecond laser. The Au ion-containing solution is prepared by mixing (3-mercaptopropyl)trimethoxysilane (MPTMS) with an aqueous solution of HAuCl4. Here, the mechanism of selective growth of gold nanostructures on the amorphized silicon is explained. Au ions in the solution placed on the FIB- or laser-processed silicon are reduced by the amorphized silicon. Silicon-dangling bond defects, which exist in the amorphized silicon, seem to reduce the Au ions. Finally, we find that the use of MPTMS is unnecessary and a simple HAuCl4 aqueous solution produces desired results.
