Brillouin scattering from metal superlattices

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:7202760

Bell, J A

Acoustic modes guided by thin-film metal superlattices were investigated using Brillouin spectroscopy. Samples were grown on both single-crystal sapphire and fused-silica substrates by alternately sputtering two different metals to yield a total thickness in the range of 0.3-0.5 ..mu..m. Structural and chemical characterization of the polycrystalline films were performed using x-ray diffraction, Rutherford backscattering, and optical interferometry. The dependence of bilayer wavelength on the elastic properties of both Cu/Nb and Mo/Ta superlattices over the range of roughly 10 to 200 A was determined. It is shown that the elastic stiffness coefficient with the largest variation is c/sub 44/. The stiffness variations determined for the Mo/Ta samples are much smaller than for Cu/Nb. It is suggested that this is due to either structural differences (Cu/Nb is fcc-bcc and Mo/Ta is bcc-bcc) or the smaller interfacial lattice mismatch for Mo/Ta. Interfacial strain is found to be strongly correlated with the stiffness variations of the Mo/Ta samples. This dissertation also reports the first observations of Love waves and Stoneley waves by Brillouin scattering. The purely transverse Love waves guided by Cu/Nb films were detected by elasto-optic scattering from the evanescent acoustic strain in the sapphire substrate.

• Research Organization: Arizona Univ., Tucson (USA)
• OSTI ID: 7202760
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER
SUPERLATTICES
MOLYBDENUM
NIOBIUM
BRILLOUIN EFFECT
TANTALUM
ELASTICITY
LOVE WAVES
SAPPHIRE
SILICA
SUBSTRATES
THIN FILMS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
CORUNDUM
ELEMENTS
FILMS
MECHANICAL PROPERTIES
METALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SEISMIC SURFACE WAVES
SEISMIC WAVES
SILICON COMPOUNDS
SILICON OXIDES
TENSILE PROPERTIES
TRANSITION ELEMENTS
360101* - Metals & Alloys- Preparation & Fabrication
360102 - Metals & Alloys- Structure & Phase Studies