Significant “smaller is softer” in amorphous silicon via irradiation-mediated surface modification

Yuecun Wang, Lin Tian, Meng Li, Zhiwei Shan

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

“Smaller is softer” is a reverse size dependence of strength, defying the “smaller is stronger” tenet. It usually results from surface-mediated displacive or diffusive deformation and is mainly found in some ultra-small-scale (below tens of nanometers) metallic materials. Here, making use of the surface modification via ion beam irradiation, we bring the “smaller is softer” into being in a covalently-bonded, hard, and brittle material-amorphous Si (a-Si) at a much larger size regime (< ∼500 nm). It is manifested as the transition from the quasi-brittle failure to the homogeneous plastic deformation as well as the decreasing yield stress with sample volume reduction at the submicron-scale regime. An analytical model of hard core/superplastic shell has been proposed to explain the artificially-controllable size-dependent softening. This surface engineering pathway via ion irradiation is not only of particular interest to tailor the strength and deformation behaviors in small-sized a-Si or other covalently-bonded amorphous solids but also of practical relevance to the utility of a-Si in microelectronics and microelectromechanical systems.
Original languageEnglish (US)
Pages (from-to)106-112
Number of pages7
JournalJournal of Materials Science and Technology
Volume166
DOIs
StatePublished - Jun 26 2023
Externally publishedYes

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics
  • Mechanics of Materials
  • Metals and Alloys
  • Ceramics and Composites
  • Mechanical Engineering

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