Brillouin Cross-Sections and Localized Phonons in CaF sub 2 /Si Heterostructures.
01 January 1989
The principal and up to six higher order acoustic surface modes from CaF sub 2 films grown epitaxially on Si(111) have been observed using Brillouin scattering. The striking modifications to the Brillouin peak intensities with layer thickness are accounted for by strong interference between the various photon coupling mechanisms and provide a critical test of the theory of surface Brillouin scattering from supported films. Angular dependence of the scattering amplitudes accounts for the different Brillouin lineshapes observed in the measurement of the dispersion of the elastic modes.