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Science 14 July 2006:
Vol. 313. no. 5784, p. 186
DOI: 10.1126/science.1125017
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Brevia

Electronic Control of Friction in Silicon pn Junctions

Jeong Young Park,1 D. F. Ogletree,1 P. A. Thiel,2 M. Salmeron1*

A remarkable dependence of the friction force on carrier concentration was found on doped silicon substrates. The sample was a nearly intrinsic n-type Si(100) wafer patterned with 2-micrometer-wide stripes of highly B-doped p-type material. The counter surface was the tip of an atomic force microscope coated with conductive titanium nitride. The local carrier concentration was controlled through application of forward or reverse bias voltages between the tip and the sample in the p and the n regions. Charge depletion or accumulation resulted in substantial differences in friction force. The results demonstrate the capability to electronically control friction in semiconductor devices, with potential applications in nanoscale machines containing moving parts.

1 Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA.
2 Ames Laboratory and Department of Chemistry and Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA.

* To whom correspondence should be addressed. E-mail: mbsalmeron{at}lbl.gov

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Nanoscale Friction Varied by Isotopic Shifting of Surface Vibrational Frequencies.
R. J. Cannara, M. J. Brukman, K. Cimatu, A. V. Sumant, S. Baldelli, and R. W. Carpick (2007)
Science 318, 780-783
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Science. ISSN 0036-8075 (print), 1095-9203 (online)