Semiconductor Manufacturing Research News
Plasmons from Metal Particles
Stanford University scientists reported insights into plasmon resonance, which occurs when light hits a metal and the electrons on the metal’s surface oscillate in waves. The report in the journal Nature explained how plasmons exist in individual metal particles as small as one nanometer in diameter, or about 100 atoms in total, much smaller than previously reported.
Artist representation of plasmon resonance. (Source: Stanford University)
Stanford doctoral candidate Jonathan Scholl said the paper provides the foundation for nano-engineering a new class of metal particles made up of between 100 and 10,000 atoms.
A nanoparticle of silver measuring just a few atoms across, for instance, will respond to photons and electrons in ways profoundly different from a larger particle or slab of silver, the university said in a detailed report on the research.
“While scientists have found a number of applications for larger nanoparticles, quantum-sized metal particles have remained largely under-utilized,” said Scholl.
The scientists used a scanning transmission electron microscope (E-STEM) installed recently at Stanford’s Center for Nanoscale Science and Engineering.
A Better Way to Make Graphene?
Researchers claimed a simpler method of making graphene production which does not involve the application of toxic chemicals. The collaborators said they have developed a graphene production method which yielded pellets that were 688 times better at conducting electricity than the widely used method of acid oxidation of graphite.
The report, in the Proceedings of the National Academy of Sciences, was co-authored by Jong-Beom Baek, a professor Ulsan National Institute of Science and Technology in South Korea, and Liming Dai, professor of macromolecular science and engineering at Case Western Reserve.
“We have developed a low-cost, easier way to mass produce better graphene sheets than the current, widely-used method of acid oxidation, which requires the tedious application of toxic chemicals,” claimed Dai.
Graphite and frozen carbon dioxide were put in a canister filled with stainless steel balls, which was turned for two days. The mechanical force produced flakes of graphite. After being treated with a solvent, the flakes separate into graphene naonsheets of five or fewer layers.
Graphene representation. (Source: Wikipedia Commons)
A solution of solvent and the nanosheets was placed on silicon wafers 3.5 by 5 cm, and heated to 900° C. The electrical conductivity of the resultant large-area films was higher than from the acid oxidation method, they said.
Baek said the method can be customized for different applications. “You can customize for electronics, supercapacitors, metal-free catalysts to replace platinum in fuel cells. You can customize the edges to assemble in two-dimensional and three-dimensional structures, ” Baek said in a report seen on the Physorg.com site.
– David Lammers
Tags: Case Western Reserve University, graphene, plasmon resonance, Stanford University