The continual drive for miniaturization of electronic transistors, with their density doubling roughly every two years, has been a mainstay of electronics development. The end result is billions of individual components on a single chip, essentially all working perfectly and continuously for years on end. Still, miniaturization cannot go on forever. We are already beginning to run into the problem that the silicon semiconductor, copper wiring and oxide insulating layers in these devices are all made out of atoms, each about 0.3 nanometers across. We have to worry about orbitals and chemical bonds — in short, quantum mechanics rules the day at these scales.
In 1974 Ari Aviram and Mark Ratner from the IBM Thomas J Watson Research Center in New York suggested using molecules themselves as electronic components. In the June issue of Physics World, Douglas Natelson explores the burgeoning field of single-molecule electronics, giving a detailed account of both the underlying physics and the potential applications in industry. At the molecular scale some of weird effects of quantum mechanics come into play. Natelson investigates the different ways in which these quantum quirks can be exploited in electronic devices and also considers the various difficulties in quantifying electronic activity at such a small scale.
From Physics Today
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