ExtremeTech reports researchers at the University of Erlangen-Nuremberg in Germany have developed the first high-performance monolithic graphene transistors using a simple lithographic etching process. The discovery could pave the way to post-silicon electronics, but don't expect it anytime soon as the transistors created by the researchers were around 100 micrometers across, or 100,000nm.
As you probably know by now, graphene has a long and wonderful list of desirable properties, including being the most conductive material yet discovered. In theory, according to early demos from the likes of IBM and UCLA, graphene transistors should be capable of switching at speeds between 100GHz and a few terahertz. The problem is, graphene doesn’t have a bandgap — an innate ability to switch on and off, depending on the voltage; it isn’t a natural semiconductor, like silicon — and so it is proving very hard to build transistors out of the stuff. Until now!
The process employed by the researchers is quite simple. Basically, by baking silicon carbide — a simple crystal of silicon and carbon, which also happens to be a well-understood semiconductor — the silicon atoms can be driven off from the layer of the crystal, leaving a single layer of graphene. A layer of graphene on its own is useless, though; you need sources, drains, and gates to produce an actual transistor. To do this, a lithographic mask is laid down, and reactive ion etching is used to define each of the transistors. Another key point was the introduction of hydrogen gas during the growth of the middle graphene channel, turning it from contact (source/drain) graphene into gate graphene. Voila: graphene transistors, with the silicon carbide and its delicious bandgap acting as the conducting layer.