Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-11-29T07:49:58.910Z Has data issue: false hasContentIssue false

Stress-Strain Response of Free-Standing Nano-Crystalline Gold Thin-Films

Published online by Cambridge University Press:  21 March 2011

Sauri Gudlavalleti
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Sharvan Kumar
Affiliation:
Brown University, Providence, RI 02912, USA
Lallit Anand
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Get access

Abstract

Free-standing gold thin-film tension specimens of thicknesses in the range 500-700 nm were fabricated by e-beam deposition methods. The films have grains which have thicknesses essentially equal to the film thickness, and an in-plane grain-size distribution which is bi-modal, with a collection of small grains with an average size of 130 nm, and another collection of larger grains with an average size of 380 nm. The films possess a strong texture with the {111} crystallographic planes aligned with the plane of the film. The thin-film specimens have been tested in simple tension using a novel testing machine which enables measurement of the elastic-plastic stress-strain response of the films with high resolution. The experiments show that the gold thin-films have an initial yield strength of around 100 MPa, which is followed by rapid strain hardening to a stress level of 360 MPa at a strain of only ~1.2%, at which point the specimens fail abruptly. Transmission electron microscopy (TEM) investigations of the deformed films shows that the rapid strain hardening is attributable to extensive dislocation activity in the larger grains. The reason behind the low ductility in our gold specimens is still unclear, but it may be attributable to the observed lack of dislocation activity in the smaller grains, whose boundaries then serve as easier sites for alternative inelastic mechanisms such as grain boundary sliding and decohesion leading to low macroscopic strains to failure.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Emery, R, Simmons, C, Mazin, B, and Povirk, G L. MRS Symp. Proc., 505, 1998.Google Scholar
[2] Weihs T, P, Hong, S, Bravman J, C, and Nix W, D. J. Mater. Res., 3:931942, 1988.Google Scholar
[3] Huang, Haibo. PhD thesis, Harvard University, 1998.Google Scholar
[4] Hoffman, R W. MRS Symp. Proc., 130:295306, 1989.Google Scholar
[5] Kang, Young-Seok and Ho, P S. J. Elec. Mater., 26:805813, 1997.Google Scholar
[6] Read, D T. Int. J. Fatigue, 3:203209, 1998.Google Scholar
[7] Gudlavalleti, S and Anand, L. Proc. ASME IMECE, 2001.Google Scholar
[8] Gudlavalleti, S, Gearing, B P, and Anand, L. To be submitted, 2001.Google Scholar