here’s a lot of talk about graphene these days, and with good reason. Consisting of just a single layer of carbon atoms roughly 0.3 nanometers thick, or 100,000 times thinner than a human hair, graphene is the thinnest known material. A team of PhD students and undergrads at UC San Diego has developed a technique that generates extremely small gaps, or nanogaps. Structures with these atomic-sized gaps could be used to detect single molecules associated with certain diseases, and could lead to microprocessors several orders of magnitude smaller than the ones in computers today. The concept, at least, is pretty simple: Shrink the space between circuits on a chip, and you can fit more circuits on that same chip.
The team, led by nanoengineering professor Darren Lipomi, specified that the way to create a smaller, well-defined gap between two nanostructures is to employ a graphene spacer, which you then etch away to create the gap.
“Making a nanogap is interesting from a philosophical standpoint,” said Lipomi in a statement. “While most efforts in nanotechnology focus on making materials, we’ve essentially made nothing ─ but with controlled dimensions.”
More specifically, you grow a single layer of graphene on a copper substrate, and then lay it onto a gold metal sheet. Since graphene sticks to gold, and not so well to copper, you can then remove the graphene layer, and transfer it to gold film with very little contamination. After this, you lay it onto another gold sheet. The result: two very thin gold films, with a single layer of graphene in between. You can then slice it into 150nm-wide nanostructures and treat them with oxygen plasma to remove the graphene.
“This new method, which we developed in our lab, is called metal-assisted exfoliation. This is the only way so far in which we can place single-layer graphene between two metals and ensure that it contains no rips, cracks, folds, or unwanted chemical species,” said Alex Zaretski (pictured below), a graduate student in Lipomi’s research group who developed the technique itself. “Metal-assisted exfoliation can potentially be useful for industries that use large areas of graphene.”
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