Effect of Finite Thickness on Elasticity Determination Using Atomic Force Microscope

Abstract

The effect of finite sample thickness on material elasticity measurements made using an Atomic Force Microscope (AFM) has been calculated. The model includes an elastic layer on an elastic foundation and simulates sample indentation under an applied load, for rigid axisymmetric tips with conical, paraboloidal, and hyperboloidal profiles. The results show that a common approach to estimating elastic modulus from force-displacement curves can lead to significant error that depends on the units of measurement. A method to estimate this error unambiguously and correct it is proposed. In addition, it is shown that elasticity estimates for monolayer thick samples using the force-modulation technique have substantial, sample thickness-dependent error. Local thickness variation can result in misleading contrast in force modulation images for samples that are several nanometers thick.

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Document Details

Document Type
Technical Report
Publication Date
Jul 01, 1998
Accession Number
ADA349087

Entities

People

  • B. B. Akhremitchev
  • Graham C. Walker

Organizations

  • University of Pittsburgh

Tags

DTIC Thesaurus Topics

  • Chemistry
  • Contrast
  • Curvature
  • Elastic Properties
  • Equations
  • Films
  • Geometry
  • Integral Equations
  • Materials
  • Measurement
  • Microscopes
  • Military Research
  • Modulation
  • Modulus Of Elasticity
  • Monomolecular Films
  • Poisson Ratio
  • Thickness

Readers

  • Computational Modeling and Simulation
  • Mechanical Engineering/Mechanics of Materials.
  • Thin Film Deposition Science.