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Science 9 November 2007:
Vol. 318. no. 5852, pp. 959 - 962
DOI: 10.1126/science.1148336
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Reports

One-Dimensional Fast Migration of Vacancy Clusters in Metals

Yoshitaka Matsukawa1,2*{dagger} and Steven J. Zinkle1

The migration of point defects, for example, crystal lattice vacancies and self-interstitial atoms (SIAs), typically occurs through three-dimensional random walk in crystalline solids. However, when vacancies and SIAs agglomerate to form planar clusters, the migration mode may change. We observed nanometer-sized clusters of vacancies exhibiting one-dimensional (1D) fast migration. The 1D migration transported a vacancy cluster containing several hundred vacancies with a mobility higher than that of a single vacancy random walk and a mobility comparable to a single SIA random walk. Moreover, we found that the 1D migration may be a key physical mechanism for self-organization of nanometer-sized sessile vacancy cluster (stacking fault tetrahedron) arrays. Harnessing this 1D migration mode may enable new control of defect microstructures such as effective defect removal and introduction of ordered nanostructures in materials, including semiconductors.

1 Materials Science and Technology Division, Oak Ridge National Laboratory (ORNL), Post Office Box 2008, TN 37831–6138, USA.
2 Center for Materials Processing, University of Tennessee, Knoxville, TN 37996–0750, USA.

* Present address: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Materials Science and Engineering Building 408A, 1304 West Green Street, Urbana, IL 61801, USA.

{dagger} To whom correspondence should be addressed. E-mail: ym2{at}uiuc.edu

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Science. ISSN 0036-8075 (print), 1095-9203 (online)