MANHASSET, NY -- IBM Research unveiled the first integrated circuit fabricated from wafer-size graphene, and demonstrated a broadband frequency mixer operating at frequencies up to 10 GHz.
The analog IC consists of a graphene transistor and a pair of inductors integrated on a silicon carbide wafer, and is aimed at wireless communications.

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 deg.C has been demonstrated with the graphene integrated circuit, according to the researchers.

According to the IBM research team, the development on the SiC wafer overcomes design hurdles by developing 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.

"While many nanotechnology breakthroughs focus on addressing the near-term shortcomings of traditional silicon microprocessors, this innovative research is a key milestone towards overcoming those design obstacles with a new material that delivers unique functionality beyond what can be achieved with silicon semiconductors," said an IBM Research spokesperson.

Researchers synthesized graphene by thermal annealing of SiC wafers to form uniform graphene layers on the surface of SiC. The fabrication of graphene circuits involves four layers of metal and two layers of oxide to form top-gated graphene transistor, on-chip inductors and interconnects.

The fabrication scheme developed can also be applied to other types of graphene materials, including chemical vapor deposited graphene films synthesized on metal films, and are also compatible with optical lithography for reduced cost and throughput, say the researchers.

Previously, the team has demonstrated standalone graphene transistors with a cut-off frequency as high as 100 GHz and 155 GHz for epitaxial and CVD graphene, for a gate length of 240 and 40 nm, respectively.

The new graphene IC breakthrough is a major milestone for IBM during its 100th year of scientific pursuits, and is also a breakthrough for the Carbon Electronics for RF Applications (CERA) program, funded by DARPA.