Electronics
Graphitic carbon has unusual properties that make it uniquely promising as an electronic material. In contrast to most conductors used in conventional electronics, graphene can form chemically stable, electrically isolated films a single atom thick[31]. Graphene components can thus be scaled down to nanometer dimensions. Thin conducting films, even if they are of macroscopic breadth, can be useful for measuring the electronic friction of adsorbed species[32]. Because the electrical resistance of graphene is sensitive to adsorbed species, thin graphene films may be used as chemical sensors. Carbon nanotube experiments show that graphene chemical sensors need not be flat[23].
Graphitic materials will address the problem of waste heat production in fast microprocessors. Graphene components can improve thermal management in three ways: by increasing heat tolerance, improving heat dissipation, and reducing heat production. Carbon has the highest melting point of any element[2], giving graphene devices the potential to operate at much higher temperature than silicon-based devices. In two dimensions, graphene can conduct heat more swiftly than any other substance, including diamond[2]. The high melting temperature and thermal conductivity of graphene will permit devices to dissipate more power than silicon devices, but the elegant solution to the waste heat problem is to make devices produce less waste heat. Cooler devices may exploit the ability of graphene to support ballistic (non-diffusive, non-ohmic) transport[30]. Ballistic graphene devices are plausible, in light of reports that gently handled multiwalled carbon nanotubes can transport carriers with a mean free path of several microns at room temperature[33].
The literature frequently reports the use of carbon nanotubes in electronic devices like chemical sensors[23,24], field emitters[25,26], transistors[27,28], and even entire circuits[29]. Less frequently, it is recognized that many of the useful properties of carbon nanotubes are, in fact, shared by other forms of graphitic carbon (nanoscale graphene ribbons, for example)[30]. Conventional lithographic techniques can be used to pattern broad graphene sheets[30]. The possibility of making entire circuits out of single graphene sheets is not remote.
Melt-grown graphite usually comes with a strongly attached, conductive foundation. To use this material for most electrical applications (for example, high-temperature resistance heating), we must remove the original graphitizing catalyst and, maybe, transfer the graphite to a dielectric substrate. The procedure, illustrated to the left, is to first deposit the dielectric support on the exposed graphite surface, then etch away the metal catalyst. Semispherical graphite shells can be etched hollow and retain their shape without the dielectric support.
While freestanding, electron-transparent membranes and bubbles can span macroscopic distances, a dielectric support may be helpful when this material is perforated to form electronic devices. The dielectric support may become superfluous when perforated graphite is patterned with hexagonal boron nitride, a refractory dielectric material[15,17].