Graphene Transistors

Graphene'spotential was recognized earlier this month when those who firststudied it in the labwon the 2010 Nobel Prize in Physics. Butresearchers are just beginning to figure out how to take advantage ofthe novel carbon material in electronic devices. Graphene has been used to make a transistor that can be switched between threedifferent modes of operation, which in conventional circuits must beperformed by three separate transistors. These configurable transistorscould lead to more compact chips for sending and receiving wirelesssignals.Chips that use fewer transistors while maintaining all the samefunctions could be less expensive, use less energy, and free up roominside portable electronics like smart phones, where space is tight. Thenew graphene transistor is an analog device, of the type that's usedfor wireless communications in Bluetooth headsets and radio-frequencyidentification (RFID) tags. Graphene's perfect structure at the atomic level provides smoothsailing for electrons, and the material conducts electrons better thanany other materials do at room temperature. So far, it's been used tomake transistors that switch at about 100 gigahertz, or 100 billiontimes per second, 10 times faster than the best silicon transistors;it's predicted the material could be made into transistors that areeven 1,000 times faster than this. And because graphene is smooth andflat, it should be compatible with the chip-making equipment atsemiconductor fabs. Graphene offers other properties besides just being a great conductor of electrons.It's also possible to change the behavior of a graphene transistor onthe fly, something that can't be done with conventional silicontransistors. The transistors that make up conventional silicon logiccircuits can only behave in one of two ways, called "n" for negative or"p" for positive--they either control the flow of electrons or the flowof "holes," or positive charges. Whether a conventional transistor isp-type or n-type is determined during fabrication. But graphene isambipolar: it can conduct both positive and negative charges.

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Graphene Transistors

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