Nanoscale-Induced Formation of Silicide around Gold Nanoparticles Encapsulated in a-Si

Abstract

Decorating thin film solar cells with plasmonic nanoparticles is being pursued, in order to improve device efficiency through increased scattering and local field enhancement. Gold nanoparticles are in particular interesting, due to their chemical inertness and plasmon resonance in the visible range of the spectrum.In this work, gold nanoparticles fabricated by a gas aggregation nanoparticle source and embedded in a-Si (a commercial solar cell material) are studied using x-ray photo-electron spectroscopy, transmission electron microscopy, electron energy-loss spectroscopy and energy dispersive X-ray spectroscopy. The formation of gold silicide around the nanoparticles is investigated, as it has important consequences for the optical and electronic properties of the structures. Differently from previous studies, in which the silicide formation is observed for gold nanoparticles and thin films grown on top of crystalline silicon or silica, it is found that silicide formation is largely enhanced around the nanoparticles, owing to their increased surface/volume ratio. A detailed gold silicide formation mechanism is presented based on the results, and strategies for optimizing the design of plasmonically enhanced solar cells with gold nanoparticles encapsulated in a-Si are discussed.

Fabrication of Gold–Silicon Nanostructured Surfaces with Reactive Laser Ablation in Liquid

“…Additionally, gold will diffuse into silicon over the ∼45 min during which the surface is immersed in solution, allowing for gold to penetrate ∼150 nm into the silicon. The mixed phases and the increasing species fraction of Au x Si deeper into the samples may be due to the propensity of Au NPs to enhance the formation of gold-silicides 73 or the result of much larger quantities of Si 0 available beneath the surface, as the majority of silicon near the surface is oxidized, and thus may be unable to form Au x Si.…”

H‐Glass Supported Hybrid Gold Nano‐Islands for Visible‐Light‐Driven Hydrogen Evolution

“…Despite having lower electronegativities for Al, Si, and P at 1.61, 1.86, and 2.2, respectively, compared to Au at 2.54, these elements tend to gain electrons, which results in a reduction of electron density in Au. [ 42–44 ] Consequently, the observed peaks in the 4f 7/2 binding energy approximately at 82.38, 83.18, and 83.98 eV are ascribed to negatively charged Au (Au δ− ), metallic Au (Au 0 ), and positively charged Au (Au δ+ ) species, respectively. However, the peak at 83.98 eV in the Au 4f spectrum is attributed to the combined influence of interactions, [ 42–44 ] Au‐P, Au‐Al, and Au‐Si, as per the STEM, EDS, and WDS findings.…”

“…[ 42–44 ] Consequently, the observed peaks in the 4f 7/2 binding energy approximately at 82.38, 83.18, and 83.98 eV are ascribed to negatively charged Au (Au δ− ), metallic Au (Au 0 ), and positively charged Au (Au δ+ ) species, respectively. However, the peak at 83.98 eV in the Au 4f spectrum is attributed to the combined influence of interactions, [ 42–44 ] Au‐P, Au‐Al, and Au‐Si, as per the STEM, EDS, and WDS findings. Figure 3f shows how different electronic states of Au vary in proportion at depths ranging from 10 to 300 nm.…”

Structural Properties of Nanometer‐Sized Gold Nanoparticles on a Silicon Substrate

“…Our results are consistent with those obtained by using other techniques such as photoemission. [54,[62][63][64] However, other spectroscopies do not provide direct structural information as does HE-XRD. Our method thus offers a useful technique for complementing earlier spectroscopic studies.…”

“…We demonstrated the formation of Au‐silicide structures below the Au NPs through inter‐diffusion and chemical reactions at the Au/Si interface, with important consequences for the electronic and optical properties. [ 64 ] Au NPs have applications such as those involving surface‐enhanced Raman scattering (SERS) [ 65 ] in lab‐on‐chip biosensors for detecting influenza [ 66 ] and Covid‐19 viruses [ 67 ] with improved sensitivity compared to the traditional techniques. Our study will thus help in designing such devices with desirable properties by providing insight into the structure of the Au/Si nano‐interface.…”