Heteroepitaxial Growth of Gold Nanostructures on Silicon by Galvanic Displacement

Abstract

This work focuses on the synthesis and interfacial characterization of gold nanostructures on silicon surfaces, including Si(111), Si(100), and Si nanowires. The synthetic approach uses galvanic displacement, a type of electroless deposition that takes place in an efficient manner under aqueous, room-temperature conditions. The case of gold-on-silicon has been widely studied and used for several applications and yet, a number of important, fundamental questions remain as to the nature of the interface. Some studies are suggestive of heteroepitaxial growth of gold on the silicon surface, whereas others point to the existence of a silicon؊gold intermetallic sandwiched between the metallic gold and the underlying silicon substrate. Through detailed high resolution transmission electron microscopy (TEM), combined with selected area electron diffraction (SAED) and nanobeam diffraction (NBD), heteroepitaxial gold that is grown by galvanic displacement is confirmed on both Si(100) and Si(111), as well as silicon nanowires. The coincident site lattice (CSL) of gold-on-silicon results in a very small 0.2% lattice mismatch due to the coincidence of four gold lattices to three of silicon. The presence of gold؊silicon intermetallics is suggested by the appearance of additional spots in the electron diffraction data. The gold؊silicon interfaces appear heterogeneous with distinct areas of heteroepitaxial gold on silicon, and others, less well-defined, where intermetallics may reside. The high resolution cross-sectional TEM images reveal a roughened silicon interface under these aqueous galvanic displacement conditions, which most likely promotes nucleation of metallic gold islands that merge over time: a Volmer؊Weber growth mechanism in the initial stages.

Gold nanoparticle integrated with nanostructured carbon and quantum dots: synthesis and optical properties

“…The patterning of Au nanoparticles on the silicon substrate was achieved in an electroless or galvanic deposition process [17,18] followed by the high-temperature annealing. Electroless Au deposition reaction was performed for different durations (45, 90, and 120 s).…”

“…Au film was deposited on the silicon substrate using acid-based wet-chemical method [17,18]. In this method, cleaned silicon substrate was treated with BOE solution to remove the surface oxide layer.…”

Improved structural features of Au-catalyzed silicon nanoneedles

“…Spontaneous formation of coherent 3D Au NPs on Si substrate is attributed to hetero-epitaxy lattice mismatch mediated Volmer-Weber growth process. A lattice mismatch $25% between the Au and Si allowed the direct formation of Au particles on the substrate surface [30][31][32]. Thus, the dispersed spherical particles grew as bigger island-like structures and finally agglomerated to form continuous film at the later stages of deposition.…”

Tailoring Optical Properties of Silicon Nanowires by Au Nanostructure Decorations: Enhanced Raman Scattering and Photodetection

“…10 Galvanic displacement is an effective way to decorate SiNWs with metallic nanoparticles, such as Au or Ag, with clean and heteroepitaxial interface. 11 In this process, silicon nanowire surface serves as both the template for particles decoration and the source of electrons that reduce the metal ions in solution. Fresh SiNW surface can provide the necessary reduction potential to facilitate the formation of uniform Ag or Au nanoparticles.…”