IBM has built on their previous graphene research and developed what is being reported as the best graphene-based integrated circuit (IC) built to date, with 10 000 times better performance than previously reported efforts.
This graphene-based IC serves as a radio frequency receiver that performs signal amplification, filtering and mixing. In tests, the IBM team was able to use the circuit to send text messages (in this case, “IBM”) without any distortion.
“This is the first time that someone has shown graphene devices and circuits to perform modern wireless communication functions comparable to silicon technology,” IBM Research director of physical sciences Supratik Guha said in a release.
The IC, which is fully described in the journal Nature Communications (“Graphene radio frequency receiver integrated circuit”), overcomes major problems previously encountered with graphene-based ICs that cause the transistor performance to degrade.
The key to overcoming this issue was a new manufacturing method. Simply put, the graphene is added late in the process to prevent it from being damaged during other manufacturing steps.
Despite the improved manufacturing method for the IC, the IBM researchers still depended on a costly method for producing the graphene that was used. They believe that if a high-quality graphene could be produced in a roll-to-roll process, the IC would become easier and cheaper to produce.
This latest circuit builds on the first integrated circuit built from graphene—developed by IBM in 2011—that was a broadband radio-frequency mixer, a fundamental component of radios that processes signals by finding the difference between two high-frequency wavelengths.
While others have judged the odds that graphene will yield benefits in electronic applications as slim to none because it lacks an inherent band gap, IBM has stayed on a steady course to test those assumptions. In early 2010, Big Blue researchers engineered a band gap into graphene large enough to pursue the use of graphene in infrared (IR) and terahertz (THz) detectors and emitters. Then a year later, IBM followed up with a graphene transistor capable of operating at 100 gigahertz that has the same gate length as silicon chips with speeds of 40 GHz. Of course, a transistor on its own can’t do much of anything, so about six months later, IBM reported building the first integrated graphene circuit that was the precursor to this latest version.
In describing the impact of the research, Shu-Jen Han of IBM Research said in an IBM blog:
“Our demonstration has the potential to improve today’s wireless devices’ communication speed, and lead the way toward carbon-based electronics device and circuit applications beyond what is possible with today’s silicon chips. Integrating graphene radio frequency (RF) devices into today’s low-cost silicon technology could also be a way to enable pervasive wireless communications allowing such things as smart sensors and RFID tags to send data signals at significant distances.”
With IBM's apparent relentless pursuit of an IC for a radio frequency receiver, it would seem that seeing these devices in our telephones at some point in the future could be a realistic prospect.
Photo: IBM Research - Zurich
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.