By Peter Pachal
Originally published on pcmag.com on June 10th, 2011
Following up their achievement of building a transistor made of graphene, IBM scientists have created the first graphene-based integrated circuit. The discovery, which the company reported yesterday in the journal Science, is a significant milestone in the evolution of graphene from a curious substance with fascinating properties to a revolutionary material that could change microelectronics forever.
The graphene-based circuit the team built is a broadband radio-frequency transmitter, found in radios. Made as a proof-of-concept that graphene circuits can work, the transmitter can handle frequencies up to 10GHz, though the researchers say the technology has much higher potential. For the transistors themselves, graphene designs have been shown to go as high as 300GHz.
"A transistor by itself is no good unless you connect it to something," Keith Jenkins, one of the researchers, told IEEE Spectrum. "[It was] a pretty difficult engineering challenge."
Graphene is inherently difficult to work with, as it's a highly conductive lattice of carbon molecules that's just a single atom thick. But putting it in a circuit introduces more problems. First, many of the circuit components in the transmitter are made from metal, which doesn't adhere to graphene very well. On top of that, the material can be damaged easily damaged by standard semiconductor etching.
The researchers addressed the fragility problem by protecting the graphene with a polymer but also coating it with a material that was sensitive to electron lithography. That way, they could protect the graphene and still remove it in specific places.
In addition to being capable of extreme high-frequency switching, graphene boasts other advantages over traditional electronics. Notably, the performance of the researchers' circuit hardly changed at all when it was heated from room temperature to 260 degrees Fahrenheit.
It's still early days for graphene, and the material has some properties that aren't perfectly suited for electronic applications. The New York Times notes that it graphene transistors don't switch on and off as completely as semiconductor-based designs do.
Still, as today's technology moves closer and closer to reaching the limits of Moore's Law, a lot of expectation is being put on graphene's carbon-based shoulders. Already it's shown a lot of promise in transistors, optical modulators, and now, complete circuits. With the demand for ever-faster computational power and network speeds very real, many of the world's devices could be graphene-powered in 10 years' time.
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