Minute graphene-based integrated circuits for wireless devices offer better performance for much lower prices
IBM researchers have made a scientific breakthrough in delivering the first wafer-scale graphene integrated circuits that are smaller than a pinhead. The circuits could heighten the sensitivity of current wireless devices.
The company said a group of IBM research scientists achieved a milestone in creating a building block for the future of wireless. In a paper published in the magazine Science, IBM researchers announced the first integrated circuit fabricated from wafer-size graphene, and demonstrated a broadband frequency mixer operating at frequencies up to 10GHz (10 billion cycles per second).
Lower Cost, Lower Power, Better Performance
Graphene, the thinnest electronic material consisting of a single layer of carbon atoms packed in a honeycomb structure, possesses superior electrical, optical, mechanical and thermal properties that could make it less expensive and use less energy inside portable electronics like smartphones.
Moreover, designed for wireless communications, the graphene-based analogue integrated circuit could improve today’s wireless devices and points to the potential for a new set of applications, IBM said.
At today’s conventional frequencies, cell phone and transceiver signals could be improved, potentially allowing phones to work where they cannot today while, pitched at much higher frequencies, military and medical personnel could build penetrative devices that could show concealed weapons or provide alternatives to medical imaging without the same radiation dangers of X-rays, IBM officials said.
Meanwhile, despite significant scientific progress in the understanding of graphene and the demonstration of high-performance devices, the challenge of integrating graphene transistors with other components on a single chip had not been realised until now. The challenge has been to overcome the poor adhesion of graphene with metals and oxides and the lack of reliable fabrication schemes to yield reproducible devices and circuits, IBM said.
However, this new integrated circuit, consisting of a graphene transistor and a pair of inductors compactly integrated on a silicon carbide (SiC) wafer, overcomes these design hurdles. IBM has developed wafer-scale fabrication procedures that maintain the quality of graphene and, at the same time, allow for its integration to other components in a complex circuitry.
“Just a few days before IBM commemorates its 100th anniversary, our scientists have achieved a nanotechnology milestone which continues the company’s century-long pursuit of innovation and technology leadership,” said T C Chen, vice president of Science and Technology at IBM Research, in a statement. “This research breakthrough has the potential to increase the performance of communication devices that enable people to interact with greater efficiency.”
The breakthrough is also a major milestone for the Carbon Electronics for RF Applications (CERA) programme, funded by DARPA, IBM said.
Uniform Graphene Layering
In an explanation of how the technology works, IBM said graphene is synthesised by thermal annealing of silicon carbide (SiC) wafers to form uniform graphene layers on the surface of the SiC. The fabrication of graphene circuits involves four layers of metal and two layers of oxide to form a top-gated graphene transistor, on-chip inductors and interconnects.
The circuit operates as a broadband frequency mixer, which produces output signals with mixed frequencies (sum and difference) of the input signals. Mixers are fundamental components of many electronic communication systems. Frequency mixing up to 10 GHz and excellent thermal stability up to 125 degrees Celsius has been demonstrated with the graphene integrated circuit, IBM said.
The fabrication scheme developed can also be applied to other types of graphene materials, including chemical vapour deposited (CVD) graphene films synthesised on metal films, and are also compatible with optical lithography for reduced cost and higher throughput.
For its part, IBM said nanotechnology is an enabling technology that is expected to spark advances in various fields. These include advanced functional materials, sensing, tools, healthcare, bio-analytics, water purification, energy technology, and more.
IBM also recently opened the Binnig and Rohrer Nanotechnology Centre – a facility for nanoscale research recently opened on the campus of IBM Research, Zurich. The building is the centrepiece of a 10-year strategic partnership in nanoscience between IBM and ETH Zurich, one of Europe’s premier technical universities, where scientists will research novel nanoscale structures and devices to advance energy and in-formation technologies, IBM officials said.