Did you know that pencil lead may just end up changing the world? Graphene is the material from which graphite, the core of your No. 2 pencil, is made. It is also the latest "wonder material," and may be the electronics industry's next great hope for the creation of extremely fast electronic devices. Researchers at North Carolina State University have found one of the first roadblocks to utilizing graphene by proving that its conductivity decreases significantly when more than one layer is present.
Graphene's structure is what makes it promising for electronics. Because of the way its carbon atoms are arranged, its electrons are very mobile. Mobile electrons mean that a material should have high conductivity. But NC State physicist Dr. Marco Buongiorno-Nardelli and NC State electrical and computer engineer Dr. Ki Wook Kim wanted to find a way to study the behavior of "real" graphene and see if this was actually the case.
"You can talk about the electronic structure of graphene, but you must consider that those electrons don't exist alone in the material," Buongiorno-Nardelli says. "There are impurities, and most importantly, there are vibrations present from the atoms in the material. The electrons encounter and interact with these vibrations, and that can affect the material's conductivity."
Buongiorno-Nardelli, Kim and graduate students Kostya Borysenko and Jeff Mullen developed a computer model that would predict the actual conductivity of graphene, both as a single layer and in a bilayer form, with two layers of graphene sitting on top of one another. It was important to study the bilayer model because actual electronic devices cannot work with only a single layer of the material present.
"You cannot make a semiconductor with just one graphite layer," Buongiorno-Nardelli explains. "To make a device, the conductive material must have a means by which it can be turned off and on. And bilayer provides such ability."
|Contact: Tracey Peake|
North Carolina State University