Ultrafast Graphene
IBM creates large arrays of transistors that are ­speedier than silicon

Source: “100-GHz Transistors from Wafer-Scale Epitaxial Graphene”
Yu-Ming Lin, Phaedon Avouris, et al.
Science 327: 662

Results: Researchers at IBM have made graphene transistors that operate at 100 gigahertz, 10 times as fast as the speediest silicon transistors of the same size and faster than previous graphene transistors. They produced large arrays of these transistors, using methods that are compatible with semiconductor manufacturing.

Why it matters: Although graphene transistors made in earlier research have shown promising speed, the techniques used for making them haven’t lent themselves to mass production. Because the new transistors are easy to make, they could be a practical substitute for conventional transistors in military communications, radar, medical and security imaging, and a variety of other applications that require high-frequency analog transistors.

Methods: The researchers heated a five-centimeter-wide wafer of silicon carbide until the silicon at the surface evaporated, leaving behind graphene, an atom-thick sheet of carbon. Then they used conventional lithographic techniques to lay down source and drain electrodes and a dielectric (or insulating) layer, resulting in a pattern of numerous transistors. The addition of a thin polymeric layer between the graphene and the dielectric layer kept electrical charges in the insulator from compromising the graphene’s electrical properties, thus dramatically improving the transistors’ performance.

Next steps: The researchers plan to improve upon their current work by building integrated circuits like those used in computer processors. They will also attempt to speed up the transistors further by making them smaller. So far, the graphene transistors they’ve made are 10 times the size of the best silicon transistors.