An international group of researchers from the University of Minnesota, Argonne National Laboratory and Seoul National University have discovered a groundbreaking technique in manufacturing nanostructures that has the potential to make electrical and optical devices smaller and better than ever before. A surprising low-tech tool of Scotch Magic tape ended up being one of the keys to the discovery.
Combining several standard nanofabrication techniques—with the final addition of the Scotch Magic tape—researchers at the University of Minnesota created extremely thin gaps through a layer of metal and patterned these tiny gaps over the entire surface of a four-inch silicon wafer. The smallest gaps were only one nanometer wide, much smaller than most researchers have been able to achieve. In addition, the widths of the gaps could be controlled on the atomic level. This work provides the basis for producing new and better nanostructures that are at the core of advanced electronic and optical devices.
One of the potential uses of nanometer-scale gaps in metal layers is to squeeze light into spaces much smaller than is otherwise possible. Researchers showed that light could readily be squeezed through these gaps, even though the gaps are hundreds or even thousands of times smaller than the wavelength of the light used. Researchers are very interested in forcing light into small spaces because this is a way of boosting the intensity of the light. The collaborators found that the intensity inside the gaps is increased by as much as 600 million times.
One of the most surprising outcomes of the research is that Scotch Magic tape was one of the keys to the discovery. Etching one-nanometer-wide gaps into metals is not feasible with existing tools. Instead, the researchers in Oh’s team constructed the nano-gaps by layering atomic-scale thin films on the sides of metal patterns and then capping the structure with another metal layer. No expensive patterning tools were needed to form the gaps this way, but it was challenging to remove the excess metals on top and expose the tiny gaps. During a frustrating struggle of trying to find a way to remove the metal films, the researcher found that by using simple Scotch Magic tape, the excess metals could be easily removed.
"The Scotch tape works nicely, which was unexpected," said the researcher. "Our technique is so simple yet can create uniform and ultra-small gaps like we’ve never been able to do before. We hope that it will rapidly be taken up by many researchers."
This story is reprinted from material from University of Minnesota, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.