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Title: Oxide driven strength evolution of silicon surfaces

Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation.
Authors:
;  [1] ;  [2] ;  [3]
  1. Field of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853 (United States)
  2. Department of Nanoengineering, SUNY Polytechnic University, Albany, New York 12203 (United States)
  3. Sandia National Laboratories, Albuquerque, New Mexico 87185-0889 (United States)
Publication Date:
OSTI Identifier:
22492951
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMIC FORCE MICROSCOPY; FRACTURE PROPERTIES; LAYERS; MOLECULAR DYNAMICS METHOD; MONOCRYSTALS; OXIDATION; OXIDES; SILICON; SIMULATION; SURFACES; X-RAY SPECTROSCOPY