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Science 22 August 2008:
Vol. 321. no. 5892, pp. 1066 - 1069
DOI: 10.1126/science.1160777
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Reports

Observation of Atomic Diffusion at Twin-Modified Grain Boundaries in Copper

Kuan-Chia Chen,1* Wen-Wei Wu,2* Chien-Neng Liao,1{dagger} Lih-Juann Chen,1 K. N. Tu3

Grain boundaries affect the migration of atoms and electrons in polycrystalline solids, thus influencing many of the mechanical and electrical properties. By introducing nanometer-scale twin defects into copper grains, we show that we can change the grain-boundary structure and atomic-diffusion behavior along the boundary. Using in situ ultrahigh-vacuum and high-resolution transmission electron microscopy, we observed electromigration-induced atomic diffusion in the twin-modified grain boundaries. The triple point where a twin boundary meets a grain boundary was found to slow down grain-boundary and surface electromigration by one order of magnitude. We propose that this occurs because of the incubation time of nucleation of a new step at the triple points. The long incubation time slows down the overall rate of atomic transport.

1 Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
2 Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan, Republic of China.
3 Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA.

* These authors contributed equally to this work.

{dagger} To whom correspondence should be addressed. E-mail: cnliao{at}mx.nthu.edu.tw

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Science. ISSN 0036-8075 (print), 1095-9203 (online)