Evolution of Structure, Composition, and Stress in Nanoporous Gold Thin Films with Grain-Boundary Cracks
- 313 Downloads
Nanoporous gold (np-Au) thin films were fabricated from Au-Ag alloy films sputtered onto substrates. At several stages of dealloying, the evolution of the microstructure and Ag content were analyzed and stress in the np-Au thin films was measured. A nanoporous structure evolved almost immediately throughout the film thickness, and the ligament width coarsened during further dealloying, with a time dependence of t 1/8. The initial alloy films, which contained 25 at. pct Au, became stress free after extended dealloying and during thermal cycling up to 200 °C. Preferential dissolution caused cracking at grain boundaries, which accommodated a portion of the volume contraction from dealloying, but the films nonetheless remained attached to their substrates.
The authors thank Ms. Sofie Burger for her assistance with the measurement of the ligament widths and Mr. Larry Rice for his support in using the SEM. The authors also acknowledge the Donors of the American Chemical Society Petroleum Research Fund (Grant No. 43324-G10), for support of this research.
- 4.M.B. Cortie, A.I. Maaroof, G.B. Smith: Gold Bull., 2005, vol. 38, pp. 14–22Google Scholar
- 11.D. Lee, M.H. Zhao, X.D. Wei, X. Chen, S.C. Jun, J. Hone, E.G. Herbert, W.C. Oliver, J.W. Kysar: Appl. Phys. Lett., 2006, vol. 89, pp. 111916-1–111916-3Google Scholar
- 13.J.Z. Zhu, E. Seker, H. Bart-Smith, M.R. Begley, R.G. Kelly, G. Zangari, W.K. Lye, M.L. Reed: Appl. Phys. Lett., 2006, vol. 89, pp. 133104-1–133104-3Google Scholar
- 16.L.J. Gibson, M.F. Ashby: Cellular Solids: Structures and Properties, 2nd ed., Cambridge University Press, Cambridge, United Kingdom, 1997, p. 206Google Scholar
- 17.S. Burger, Y. Sun, F. Yang, and T.J. Balk: University of Kentucky, Lexington, KY, unpublished research, 2007Google Scholar
- 21.W.D. Nix: Metall. Trans. A, 1989, vol. 20A, pp. 2217–45Google Scholar
- 22.Y. Sun, T.J. Balk: Mater. Res. Soc. Symp. Proc., 2006, vol. 924, pp. Z1.2.1–6Google Scholar
- 27.B.D. Cullity, S.R. Stock: Elements of X-Ray Diffraction, 3rd ed., Prentice-Hall, Inc., Upper Saddle River, NJ, 2001, pp. 638–39Google Scholar
- 28.R.W. Balluffi, S.M. Allen, W.C. Carter: Kinetics of Materials, 1st ed., John Wiley & Sons, Inc., Hoboken, NJ, 2005, pp. 368–402Google Scholar
- 30.L.B. Freund, S. Suresh: Thin Film Materials: Stress, Defect Formation, and Surface Evolution, 1st ed., Cambridge University Press, Cambridge, United Kingdom, 2003, pp. 197–200Google Scholar