New graphene inverters could lead to improved transistors

After its discovery in 2004, graphene — a one-atom-thick layer of carbon that conducts electricity with little resistance or heat generation — was touted as a potential replacement for silicon, possibly leading to devices with simplified circuits that might be less expensive to manufacture.

However, researchers have discovered that it has no band gap — a trait that is needed for switching 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 University doctoral student Hong-Yan Chen.

Electrons in semiconductors such as 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.