Morphological evolution of gold nanoparticles on silicon nanowires and their plasmonics

Abstract

One-dimensional heterostructures composed of silicon (Si) nanowires and uniformly decorated with gold (Au) nanoparticles were fabricated and used as a substrate for organic detection based on the surfaceenhanced Raman spectroscopy. Si nanowires were grown via a silane-based chemical vapor deposition approach. The controlled decoration of Au nanoparticles on the Si nanowires was achieved using wetchemical nucleation and followed by a thermal treatment process. Various annealing parameters were studied to control the shape, size, and surface dispersion of Au nanoparticles on the heterostructures.Microscopic methods were used to evaluate the configuration or morphological evolution (size, interparticle spacing and density) of nanoparticles at different annealing conditions. The influence of annealing on the chemical composition of Au nanoparticles were analyzed using X-ray photoelectron spectroscopy (XPS) and the phase transformation kinetics was also studied. Finally, surface-enhanced Raman spectroscopy was used to sense organic species and this was studied for various morphologies of nanowire heterostructures.

Catalytic Activity of Silicon Nanowires Decorated with Gold and Copper Nanoparticles Deposited by Pulsed Laser Ablation

“…Typical spectra relevant to Au4f and Cu2p 3/2 regions obtained on pristine AuNPs@SiNWs and CuNPs@SiNWs materials, respectively, are presented in Figure 4. The main Au4f 7/2 component falls at BE = 84.2 ± 0.1 eV (Figure 4a), which can be ascribed to gold coordinated to silicon in a silicide state in agreement with previous findings about energy shift towards higher BE when a Si–Au interface is created [41]. …”

Surface physics of semiconducting nanowires

“…In contrast to the electrochemical devices described in the previous paragraph, in this case the Si NWs do not represent the active part of the device (that is instead composed by metal NPs), but they play, however, a crucial role in the detection process. The three reasons of the interest for such kind of systems can be listed as follows: i) the ease of functionalizing the Si NWs surface with Ag [189] or Au NPs [198] of different shape and dimensions [151]. Indeed the HF treatment of Si NW surfaces creates a perfect platform for metal ions reduction' reaction hence offering the possibility to easily build metal NPs@SiNW-based SERS substrates with enhancement factor values of 10 6−10 (see Fig.…”

Self-assembly of Au/MoS2 quantum dots core-satellite hybrid as efficient electrocatalyst for hydrogen production

“…It can be seen from Fig. 2d that the binding energies of Au 4f were located at 84.1 and 87.7 eV, belonging to the peaks of Au 0 and Au + , respectively [23]. This result illustrated that existence of gold was mainly metallic Au and Au δ+ in the hybrid.…”