WEST LAFAYETTE, Ind. - Researchers are making progress in creating digital transistors using a material called graphene, potentially sidestepping an obstacle thought to dramatically limit the material's use in computers and consumer electronics.
Graphene is a one-atom-thick layer of carbon that conducts electricity with little resistance or heat generation. After its discovery in 2004 - which earned a Nobel Prize in physics - it was touted as a potential replacement for silicon, possibly leading to ultrafast devices with simplified circuits that might be less expensive to manufacture.
However, graphene's luster has dulled in recent years for digital applications as researchers have discovered that it has no "band gap," a trait that is needed to switch on and off, which is critical for digital transistors.
"The fact that graphene is a zero-band-gap material by nature has raised many questions in terms of its usefulness for digital applications," said Purdue doctoral student Hong-Yan Chen.
Electrons in semiconductors like silicon exist at two energy levels, known as the valence and conduction bands. The energy gap between these two levels is called the band gap. Having the proper band gap enables transistors to turn on and off, which allows digital circuits to store information in binary code consisting of sequences of ones and zeroes.
Chen has led a team of researchers in creating a new type of graphene inverter, a critical building block of digital transistors. Other researchers have created graphene inverters, but they had to be operated at 77 degrees Kelvin, which is minus 196 Celsius (minus 320 Fahrenheit).
"If graphene could be used in digital applications, that would be really important," said Chen, who is working with Joerg Appenzeller, a professor of electrical and computer engineering and scientific director of nanoelectronics at Purdue's Birck Nanotechnology Center.
The Purdue researcher
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