Thickness Resonance Acoustic Microscopy for Nanomechanical Subsurface Imaging

Gajendra S. Shekhawat*, Arvind K. Srivastava, Vinayak P. Dravid, Oluwaseyi Balogun

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

A nondestructive scanning near-field thickness resonance acoustic microscopy (SNTRAM) has been developed that provides high-resolution mechanical depth sensitivity and sharp phase contrast of subsurface features. In SNTRAM technology, we excited the sample at its thickness resonance, at which a sharp change in phase is observed and mapped with a scanning probe microscopy stage in near field to provide nanometer-scale nanomechanical contrast of subsurface features/defects. We reported here the remarkable subsubsurface phase contrast and sensitivity of SNTRAM by exciting the sample with a sinusoidal elastic wave at a frequency equal to the thickness resonance of the sample. This results in a large shift in phase component associated with the bulk longitudinal wave propagating through the sample thickness, thus suggesting the usefulness of this method for (a) generating better image contrast due to high S/N of the transmitted ultrasound wave to the other side of the sample and (b) sensitive detection of local variation in material properties at much better resolution due to the sharp change in phase. We demonstrated that the sample excited at the thickness resonance has a more substantial phase contrast and depth sensitivity than that excited at off-resonance and related acoustic techniques. Subsurface features down to 5-8 nm lateral resolution have been demonstrated using a standard sample.

Original languageEnglish (US)
Pages (from-to)6139-6145
Number of pages7
JournalACS nano
Volume11
Issue number6
DOIs
StatePublished - Jun 27 2017

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Keywords

  • acoustic microscopy
  • contact resonance
  • nanomechanical imaging
  • sample thickness resonance
  • scanning near-field detection
  • subsurface imaging

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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