Carbon transistors could outperform the fastest chip materials today, according to researchers at the University of Maryland. A College Park team recently characterized graphene monolayers, sheets of pure carbon just one atom thick--an artist's rendering of the graphene lattice is depicted here (black) above the image made from an optical microscope in which graphene is the slightly darker purple area. The lighter purple is the silicon dioxide substrate. The electrodes (gold) are spaced about 20 microns apart. The electron mobility of the graphene monolayers was found to be about 15,000 cm2/Vs regardless of temperature, which is unusual--usually mobility is inversely proportional to temperature (the lower the better). The lattice vibrations in graphene crystalline matrix were measured to be so weak that secondary effects like impurities and substrate choice had a bigger impact than did phonons. With a better substrate--perhaps silicon carbide, diamond or air gaps--the electron mobilities could be as high as 40,000 cm2/Vs, limited mostly by impurities. Remove those impurities, and the researchers speculated that graphene could achieve electron mobilities of 200,000 cm2/Vs at room temperature--which is more than 140-times better than silicon.