Researchers
at Rensselaer Polytechnic Institute developed a new method for creating a layer
of gold nanoparticles that measures only billionths of a meter thick. These
self-assembling gold coatings with features measuring less than 10 nm could
hold important implications for nanoelectronics manufacturing.
In
addition, Sang-Kee Eah, assistant professor in the Department of Physics,
Applied Physics, and Astronomy at Rensselaer,
demonstrated how the gold nanoparticles assemble into a unique uniform pattern
called a superlattice. Eah observed a superlattice measuring 20 microns, with a
distance between lines of nanoparticles—or lattice constant—of 8.8 nm. He says
the 20-micron superlattice domain is the largest ever documented, and this new
technique could lead to even larger superlattices with even tinier features.
"Thinking
about semiconductors, this discovery could offer new solutions for scaling down
the features of today's most advanced 32-nm computer chips to have features in
the range of less than 20 nm, or even less than 10 nm," Eah says. He used
scanning electron microscopy, with Moire interference patterns, to measure the
boundaries of the superlattice.
Results
of the study, titled "A very large two-dimensional superlattice domain of
monodisperse gold nanoparticles by self-assembly," were recently published in the Journal of Materials Chemistry.
To create the nanolayer, Eah infused liquid
toluene—a common industrial solvent—with gold nanoparticles. The nanoparticles
form a flat, closely packed monolayer of gold on the surface of the liquid
where it meets air. By moving the nanolayer of gold nanoparticles to another
air-water surface, the large superlattice was formed and coated onto a silicon
wafer after the toluene and water evaporated.
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