The unsung heroes of the microelectronics revolution are impurities intentionally added to semiconducting materials. A sprinkling of such atoms as boron or phosphorus, for example, is pivotal to much of the electronic and optical performance that makes microchips useful.
Nevertheless, attempts to include such impurities in tiny clumps of atoms known as semiconductor nanocrystals have often failed. A study in the July 7 Nature offers an explanation for this roadblock—and a way around it.
Experiments on the nanocrystals, also called quantum dots, find them promising as fluorescent tracers for monitoring biomolecules (SN: 8/7/04, p. 94: Available to subscribers at Quantum dots light up cancer cells in mice) and as additi