We report parametric studies of elastic wave generation by a pulsed laser and associated spalling of thin surface films by the corresponding high stresses. Two different substrate materials, single crystal Si (100) and fused silica, are considered. Spallation behavior of Al thin films is investigated as a function of substrate thickness, film thickness, laser energy, and various parameters governing the source. Surface displacement due to the stress wave is measured by Michaelson interferometry and used to infer the stresses on the film interface. Consistent with previous studies, the maximum stress in the substrate and at the film/substrate interface increases with increasing laser fluence. For many of the conditions tested, the substrate stress is large enough to damage the Si. Moreover, the maximum interface stress is found to increase with increasing film thickness, but decrease with increasing substrate thickness due to geometric attenuation. Of particular significance is the development of a decompression shock in the fused silica substrates, which results in very high tensile stresses at the interface. This shock enhances the failure of thin film interface, especially in thicker samples.

Original languageEnglish (US)
Pages (from-to)74-83
Number of pages10
JournalExperimental Mechanics
Issue number1
StatePublished - Mar 2002


  • Decompression shock
  • Interface adhesion
  • Laser spallation
  • Stress wave
  • Thin film

ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics


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