Silicon-based nanostructures are essential building blocks for nanoelectronic
devices and nano-electromechanical systems (NEMS). As the silicon device size
continues to scale down, the surface to volume ratio becomes larger, rendering the
properties of surfaces and interfaces more important for improving the properties of the
nano-devices and systems. One of those properties is the friction, which is important in
controlling the functionality and reliability of the nano-device and systems. The goal of
this dissertation is to investigate the deformation and friction behaviors of single
crystalline silicon nanolines (SiNLs) using nanoindentation techniques.
Following an introduction and a summary of the theoretical background of
contact friction in Chapters 1 and 2, the results of this thesis are presented in three
chapters. In Chapter 3, the fabrication of the silicon nanolines is described. The
fabrication method yielded high-quality single-crystals with line width ranging from
30nm to 90nm and height to width aspect ratio ranging from 10 to 25. These SiNL
structures have properties and dimensions well suited for the study of the mechanical and friction behaviors at the nanoscale. In Chapter 4, we describe the study of the mechanical
properties of SiNLs using the nanoindentation method. The loading-displacement curves
show that the critical load to induce the buckling of the SiNLs can be correlated to the
contact friction and geometry of SiNLs. A map was built as a guideline to describe the
selection of buckling modes. The map was divided into three regions where different
regions correlate to different buckling modes including Mode I, Mode II and slidingbending
of SiNLs. In Chapter 5, we describe the study of the contact friction of the SiNL
structures. The friction coefficient at the contact was extracted from the loaddisplacement
curves. Subsequently, the frictional shear stress was evaluated. In addition,
the effect of the interface between the indenter and SiNLs was investigated using SiNLs
with surfaces coated by a thin silicon dioxide or chromium film. The material of the
interface was found to influence significantly the contact friction and its behavior. Cyclic
loading-unloading experiments showed the friction coefficient dramatically changed after
only a few loading cycles, indicating the contact history is important in controlling the
friction behaviors of SiNLs at nanoscales. This thesis is concluded with a summary of the
results and proposed future studies. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/6576 |
| Date | 20 October 2009 |
| Creators | Luo, Zhiquan |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Format | electronic |
| Rights | Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
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