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Effective elastic constants of superlattice films measured by line-focus acoustic microscopy

Journal Article · · Journal of Engineering Materials and Technology
DOI:https://doi.org/10.1115/1.2804732· OSTI ID:131516
; ; ;  [1]
  1. Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
The effective elastic constants of single-crystal nitride superlattice films have been determined by calculation and by measurement methods. The calculation method uses formulas to calculate the effective elastic constants of superlattices from the measured elastic constants of the constituent layers. The calculated effective elastic constants are tested by comparing the corresponding surface acoustic wave (SAW) velocities calculated for thin-film/substrate systems with the corresponding SAW velocities measured by line-focus acoustic microscopy (LFAM). The measurement method determines the effective elastic constant of the superlattices directly from the SAW velocity dispersion data measured by LFAM. Two kinds of superlattice films are considered: one has relatively flat and sharp interfaces between layers, and the other has rough interfaces with interdiffusion. The calculation method has yielded very good results for the superlattices with flat and sharp interfaces but not for the superlattices with rough interfaces. The measurement method yields results for both kinds, with the restriction that the constituent layers have similar crystal symmetries.
Sponsoring Organization:
USDOE
DOE Contract Number:
FG02-86ER13484
OSTI ID:
131516
Journal Information:
Journal of Engineering Materials and Technology, Journal Name: Journal of Engineering Materials and Technology Journal Issue: 4 Vol. 117; ISSN 0094-4289; ISSN JEMTA8
Country of Publication:
United States
Language:
English