New spin on doping

Novel electronic devices based upon nanotechnology may soon be realised due to a new understanding of how impurities, or 'dopants,' can be intentionally incorporated into semiconductor nanocrystals.

This understanding, announced yesterday by researchers at the US Naval Research Laboratory (NRL) and the University of Minnesota (UMN), should help enable a variety of new technologies ranging from high-efficiency solar-cells and lasers to futuristic 'spintronic' and ultra-sensitive biodetection devices. The complete findings of the study are published in the July 7, 2005, issue of the journal Nature.

Nanocrystals are tiny semiconductor particles just a few millionths of a millimetre across. Due to their small size, they exhibit unique electronic, optical, and magnetic properties that can be utilised in a variety of technologies. To move toward this end, chemical methods have been optimised over the last 20 years to synthesise extremely pure nanocrystals. More problematic, however, has been the goal of controllably incorporating selected impurities into these particles. Conventional semiconductor devices, such as the transistor, would not operate without such impurities. Moreover, theory predicts that dopants should have even greater impact on semiconductor nanocrystals. Thus, doping is a critical step for tailoring their properties for specific applications.