Scientists squash 10,000 graphene transistors onto your pinky

Scientists in the US have found a way of growing graphene on etched silicon carbide, producing the highest ever density of graphene transistors:“ an array of 10,000 top-gated transistors on a .24cm square chip. (This is about the size of my smallest fingernail, although other fingernails may vary.)

The new technique,“ which directs the growth of graphene on templates etched into the silicon carbide, allows the graphene to form in smooth edged nano ribbons. This is important because using electron beams or other cutting techniques can leave ragged edges which rather spoil the flow of electrons through the device.

The team create their templates using two established techniques: first they etch tiny steps into the wafer. Any rough edges are removed by heating the wafer to 1,500 degrees C. Next they grow the graphene by driving off the silicon atoms from the surface, controlling the heating time to allow the carbon to grow only on the edges of the contours.

Walt de Heer, a professor in the Georgia Tech School of Physics explains in the announcement that the technique takes advantage of the fact that graphene will grow preferentially on facets of the silicon-carbide crystal.

This means the properties of the nanoribbon can be precisely controlled by careful pattern design. "Cutting steps of various depths allows us to create graphene structures that are interconnected in the way we want them to be," Prof. de Heer explains.

He adds that because the shape of a graphene ribbon determines whether it is a conductor or semi-conductor. This fine level of control of the nanoribbons means the device leads and semiconducting ribbons can all be made from graphene, eliminating the resistance than can build up at junctions between two different materials.

The work is published in the October 3 edition of Nature Nanotechnology, and you can read the press announcement here.