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Ultra-simple method for creating nanoscale gold coatings developed

Date:
June 21, 2010
Source:
Rensselaer Polytechnic Institute
Summary:
Researchers have developed a new, ultra-simple method for making layers of gold that measure only billionths of a meter thick. The process, which requires no sophisticated equipment and works on nearly any surface including silicon wafers, could have important implications for nanoelectronics and semiconductor manufacturing.
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Researchers at Rensselaer have developed a new, ultra-simple method for making layers of gold that measure only billionths of a meter thick. As seen in the research image, drops of gold-infused toluene applied to a surface evaporate within a few minutes and leave behind a uniform layer of nanoscale gold. The process requires no sophisticated equipment, works on nearly any surface, takes only 10 minutes, and could have important implications for nanoelectronics and semiconductor manufacturing.
Credit: Image courtesy of Rensselaer Polytechnic Institute

Researchers at Rensselaer Polytechnic Institute have developed a new, ultra-simple method for making layers of gold that measure only billionths of a meter thick. The process, which requires no sophisticated equipment and works on nearly any surface including silicon wafers, could have important implications for nanoelectronics and semiconductor manufacturing.

Sang-Kee Eah, assistant professor in the Department of Physics, Applied Physics, and Astronomy at Rensselaer, and graduate student Matthew N. Martin infused liquid toluene -- a common industrial solvent -- with gold nanoparticles. The nanoparticles form a flat, closely packed layer of gold on the surface of the liquid where it meets air. By putting a droplet of this gold-infused liquid on a surface, and waiting for the toluene to evaporate, the researchers were able to successfully coat many different surfaces -- including a 3-inch silicon wafer -- with a monolayer of gold nanoparticles.

"There has been tremendous progress in recent years in the chemical syntheses of colloidal nanoparticles. However, fabricating a monolayer film of nanoparticles that is spatially uniform at all length scales -- from nanometers to millimeters -- still proves to be quite a challenge," Eah said. "We hope our new ultra-simple method for creating monolayers will inspire the imagination of other scientists and engineers for ever-widening applications of gold nanoparticles."

Results of the study, titled "Charged gold nanoparticles in non-polar solvents: 10-min synthesis and 2-D self-assembly," were published recently in the journal Langmuir.

Whereas other synthesis methods take several hours, this new method chemically synthesizes gold nanoparticles in only 10 minutes without the need for any post-synthesis cleaning, Eah said. In addition, gold nanoparticles created this way have the special property of being charged on non-polar solvents for 2-D self-assembly.

Previously, the 2-D self-assembly of gold nanoparticles in a toluene droplet was reported with excess ligands, which slows down and complicates the self-assembly process. This required the non-volatile excess ligands to be removed in a vacuum. In contrast, Eah's new method ensures that gold nanoparticles float to the surface of the toluene drop in less than one second, without the need for a vacuum. It then takes only a few minutes for the toluene droplet to evaporate and leave behind the gold monoloayer.

"The extension of this droplet 2-D self-assembly method to other kinds of nanoparticles, such as magnetic and semiconducting particles, is challenging but holds much potential," Eah said. "Monolayer films of magnetic nanoparticles, for instance, are important for magnetic data storage applications. Our new method may be able to help inform new and exciting applications."

Co-authors on the paper are former Rensselaer undergraduate researchers James I. Basham '07, who is now a graduate student at Pennsylvania State University, and Paul Chando '09, who will begin graduate study in the fall at the City College of New York.

The research project was supported by Rensselaer, the Rensselaer Summer Undergraduate Research Program, the National Science Foundation (NSF) Research Experiences for Undergraduates, and the NSF's East Asia and Pacific Summer Institutes and Japan Society for the Promotion of Science.

Watch a video demonstration of this new fabrication process at: http://www.youtube.com/watch?v=nqkwM9o1s-w


Story Source:

The above post is reprinted from materials provided by Rensselaer Polytechnic Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. Matthew N. Martin, James I. Basham, Paul Chando, Sang-Kee Eah. Charged Gold Nanoparticles in Non-Polar Solvents: 10-min Synthesis and 2D Self-Assembly. Langmuir, 2010; 26 (10): 7410 DOI: 10.1021/la100591h

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Rensselaer Polytechnic Institute. "Ultra-simple method for creating nanoscale gold coatings developed." ScienceDaily. ScienceDaily, 21 June 2010. <www.sciencedaily.com/releases/2010/06/100616122154.htm>.
Rensselaer Polytechnic Institute. (2010, June 21). Ultra-simple method for creating nanoscale gold coatings developed. ScienceDaily. Retrieved July 29, 2015 from www.sciencedaily.com/releases/2010/06/100616122154.htm
Rensselaer Polytechnic Institute. "Ultra-simple method for creating nanoscale gold coatings developed." ScienceDaily. www.sciencedaily.com/releases/2010/06/100616122154.htm (accessed July 29, 2015).

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