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Now Available: Innovators Under 35 2013 See The 2013 List »

Fengnian Xia, 34

Replacing silicon with graphene


Replaced: 1) Gate electrode 2) Insulator 3) Polymer 4) Graphene sheets 5) Gate electrode. At the heart of this field-effect transistor, two sheets of graphene, rather than a block of silicon, control the flow of electricity through the device.
Credit: Emily Cooper

Fengnian Xia has found a way to build a graphene transistor that blocks electrons efficiently when it's off—a step in the direction of graphene-based electronics, which could lead to smaller, faster microprocessors.

Graphene is a promising material for transistors because it conducts electricity better than silicon does. Unfortunately, it's hard to stop the flow of electrons in graphene, and that's an essential function for any transistor. Xia's solution is based on a type of transistor in which an electric field is applied to two layers of graphene. In theory, this arrangement should stop the flow of electrons, but in practice, results were disappointing until Xia put a thin polymer layer on top of the graphene during fabrication: the polymer kept the electrical properties of the layers from being ruined as later layers were added to make other parts of the transistor.

Xia has also demonstrated that graphene can be used in ultrafast photodetectors for optical communications. The ultimate goal, he says, is an integrated system that uses graphene for both communications and computing. That would mean chips could use fiber optics instead of having their inputs and outputs bottlenecked by the relatively sluggish speeds of metal wires. —Katherine Bourzac

2011 TR35 Winners

Solomon Assefa

Replacing wires with light in chips

Christopher Bettinger (video)

Tailoring polymers for biodegradable implants

Alexandra Boltasseva

Using semiconductors to steer light

Jennifer Dionne (video)

Solar cells that see more light

Dae-Hyeong Kim

Stretchable electronics for medical devices

Fengnian Xia (video)

Replacing silicon with graphene


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