Nature-De Wit-Mackey-2002 Comment

nnews and viewsantimony atoms among all the silicon atoms clusters is random. This suggests that over- they will also be important in increasing ourcoming carrier saturation at very high dopantin the crystal is like searching for the prover- understanding of a wide range of complexbial needle in a haystack. To ‘see’ the anti- concentrations will be a major challenge. materials.Seeing is frequently the first step towardsmony dopant atoms, the researchers adapted Paul S. Peercy is at the College of Engineering,a powerful technique — scanning transmis- understanding. This first, unambiguous University of Wisconsin, 1415 Engineering Drive,5sion electron microscopy observation of single atoms bonded inside a— to image almost Madison, Wisconsin 53706-1691, USA.all the antimony atoms in the silicon crystal, bulk solid environment has wide-ranging e-mail: peercy@engr.wisc.eduimplications for the analysis of single atoms 1. Voyles, P. M., Muller, D. A., Grazul, J. L., Citrin, P. H. &even individual antimony atoms. Gossmann, H.-J. L. Nature 416, 826–829 (2002).The first critical step was to prepare thin and of clusters of two, three or four atoms —2. 2001 International Technology Roadmap for Semiconductorscrystals — only 9 or 11 atoms thick — lack- and for our efforts to understand the struc-(Semiconductor Industry Association, 2001);ing any surface or near-surface disorder that ture of impurities and alloy constituents in www.semichips.org/pre_technology.cfm 1 3. ...