Walter de Heer with his graphene semiconductor – Georgia Institute of Technology
Researchers at the Georgia Institute of Technology have created the world’s first functional semiconductor made from graphene, paving the way for smaller and faster electronic devices.
Graphene – a single sheet of carbon atoms arranged in a hexagonal lattice – has superlative physical properties, such as high-speed electrical conductivity. Although there are few commercial applications utilising graphene, it is considered to have great promise across applications spanning medical devices, photovoltaic cells and displays.
This latest development could open up a whole new field of electronics.
It comes at a time when silicon could be reaching its physical limits in the face of continued demand for faster computing and smaller devices.
The project was led by Professor Walter de Heer of Georgia Tech, with collaborators from Atlanta, Georgia, and Tianjin, China. Together, they produced a graphene semiconductor that is compatible with conventional microelectronics processing methods – a necessity for any practical alternatives to silicon. Their research was published in Nature.
The team overcame a longstanding obstacle that has caused grief for graphene researchers for decades. Semiconductors require a band gap, across which electrons might or might not be able to jump. Graphene’s lack of a band gap meant that many scientists expected graphene electronics to be doomed – until now.
“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,” said de Heer. “But the story of our work for the past 10 years has been: can we get this material to be good enough to work?”
De Heer started working with graphene as a potential semiconductor more than 20 years ago. “We were motivated by the hope of introducing three special properties of graphene into electronics,” he said. “It’s an extremely robust material, one that can handle very large currents, and can do so without heating up and falling apart.”
His team worked out how to grow graphene – epitaxial graphene – on the crystal face of silicon carbide wafers. This could chemically bond to the silicon carbide and, with some doping, start to show semiconducting properties.
The graphene semiconductor has at least 10 times greater electron mobility than silicon, meaning the electrons move with little resistance through the material. Eventually, this could translate into faster computing. “It’s like driving on a gravel road versus driving on a freeway,“ said de Heer. “It’s more efficient, it doesn’t heat up as much, and it allows for higher speeds so that the electrons can move faster.”
This is the only 2D semiconductor with all the necessary products to be used in nanoelectronics, and it has electrical properties far beyond any other 2D semiconductors in development.
Professor Lei Ma, study co-author and director of the Tianjin International Centre for Nanoparticles and Nanosystems, said: “A longstanding 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. 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 realising graphene-based electronics.”
