Researchers at the Georgia Institute of Technology developed a functional semiconductor made from graphene. Their new semiconductor is compatible with conventional microelectronics processing methods, which was a requirement for any viable alternative to the use of silicon. This breakthrough technology could lead to a new way of doing electronics, particularly in the field of quantum computing.
The team – led by Dr. Walter de Heer, Regents’ Professor of physics at Georgia Tech – had to address a major hurdle in creating graphene electronics, the “band gap.” This is a crucial electronic property that allows semiconductors to switch on and off, which until now, did not exist within graphene.
“A long-standing problem in graphene electronics is that graphene didn’t have the right band gap and couldn’t switch on and off at the correct ratio,” said Lei Ma, director and cofounder (with de Heer) of the Tianjin International Center for Nanoparticles and Nanosystems at Tianjin University, and a co-author of the paper. “Over the years, many have tried to address this with a variety of methods. Our technology achieves the band gap, and is a crucial step in realizing graphene-based electronics.”
To successfully create graphene with a bandgap, the team grew graphene on silicon carbide wafers using special furnaces to produce epitaxial graphene – a single layer that grows on a crystal face of the silicon carbide. With this technique, the epitaxial graphene chemically bonded to the silicon carbide and started to show semiconducting properties.
A semiconducting material must be capable of being manipulated, without damage to its properties. To test their graphene semiconductor, the team placed atoms on the graphene that “donate” electrons to the system – a technique called doping. Not only did the new semiconductor successfully demonstrate that it could serve as a good conductor, without damage to its material or properties, it also showed that it has ten times greater mobility than silicon.
“We now have an extremely robust graphene semiconductor with 10 times the mobility of silicon, and which also has unique properties not available in silicon,” de Heer said. “But the story of our work for the past 10 years has been, ‘Can we get this material to be good enough to work?’”