Templating growth of gold nanostructures with a CdSe quantum dot array

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Thin gold nanolayers are crucial for optoelectronic devices, serving as stable metal contacts and connecting recombination centers.
• Optimal device performance relies on uniform, large-area quantum dot arrays with controlled positions and sizes.
• The nanomorphology of gold layers significantly impacts device characteristics.

Purpose of the Study:

• To investigate the mechanism of gold nanostructure formation during sputter deposition on quantum dot arrays.
• To understand how quantum dots influence the development of gold layer morphology.
• To assess the feasibility of templating gold nanostructures on quantum dot arrays.

Main Methods:

• Time-resolved grazing incidence small-angle X-ray scattering (GISAXS) was employed to probe structure formation during gold sputter deposition.
• Gold was deposited onto cadmium selenide (CdSe) quantum dot arrays with a characteristic spacing of approximately 7 nm.
• In-situ monitoring captured the evolution of gold nanomorphology from initial deposition to layer completion.

Main Results:

• Gold preferentially deposits on top of quantum dots in the initial stages, utilizing them as nucleation sites.
• Subsequent coarsening of surrounding gold nanoparticles forms gold-dot clusters, leading to a complete layer.
• Vertical growth on these clusters forms a gold capping layer, with cluster boundaries shifting due to ripening.
• Templating of gold on CdSe quantum dot arrays is achievable at low gold coverage.

Conclusions:

• Quantum dots effectively template the growth of gold nanolayers, controlling nanomorphology.
• The observed growth mechanism, involving nucleation, coarsening, and vertical growth, is key to forming uniform gold layers.
• This templating approach offers a viable method for fabricating essential components in optoelectronic devices.