Selective deposition of gold particles onto silicon at the nanoscale controlled by a femtosecond laser through galvanic displacement.

Abstract

Control of the deposition location and morphology of metals on semiconductors is of considerable importance for the fabrication of metal–semiconductor hybrid structures. For this purpose, selective nanoscale deposition of gold on silicon was successfully achieved by a two-step method in this paper. The first preparation step comprises the fabrication of ripples with a femtosecond laser. The second preparation step is to immerse the samples in a mixed aqueous solution of hydrofluoric acid (HF) and chloroauric acid (HAuCl4). The periodically ablated ripple structures on silicon surfaces fabricated by the femtosecond laser changed the physical and chemical properties of silicon and then controlled the nucleation positions of gold nanoparticles. Gold particles tend to grow in raised positions of the ripples and no substantial growth was observed in the recesses of the ablated ripple structures. Similar phenomena were observed on the modified ripple structures; this led to the formation of periodically distributed gold sub-micron wires. Above all, this paper proposes a new mask-free method of selective metal electroless deposition that can be realized without complicated experimental equipment and tedious experimental operations.