Doped-Up Nano. If the chips in your computer didn't have impurities, you wouldn't be reading this message. That's because conventional semiconductor devices like the transistor must be "doped" with impurities, such as atoms of phosphorus, in order to operate. The same goes for many future devices to be built from nanocrystals - particles of semiconductor material just a few millionths of a millimeter across. Unfortunately, methods of intentionally incorporating impurities, or "dopants," into nanoparticles have often eluded scientists. Now, researchers at the Naval Research Laboratory and the University of Minnesota have learned why such doping often fails and how to overcome it. Using their insights, they have successfully doped nanocrystals of cadmium selenide-a commonly studied nanocrystal-with atoms of manganese, a feat previously considered impossible. The findings should usher in a variety of new technologies, ranging from high-efficiency solar cells and lasers to futuristic "spintronic" and ultra-sensitive biodetection devices. Steven C. Erwin, Lijun Zu, Michael I. Haftel, Alexander L. Efros, Thomas A. Kennedy and David J. Norris, Nature, 436, 91-94 (7 July 2005).

Research team members included Lijun Zu, a Chemical Engineering and Materials Science graduate student at the University of Minnesota (UMN), and David Norris, a faculty member of the UMN's Materials Research Science and Engineering Center (MRSEC). The UMN MRSEC, Office of Naval Research, and National Science Foundation Division of Chemical and Transport Systems provided funding for the research.

Also featured in Chemical & Engineering, July 11, 2005, Volume 83, Number 28,

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