Typical Brillouin spectra recorded in backscattering from the organo-silicate glass sample at scattering angles of , 30°, 45°, and 60°. Peaks observed for at the lowest scattering angles are the low lying standing longitudinal waves (1LSM and 2LSM). As increases, transverse resonances (2TSM and 3TSM) emerge. The calculated cross section is illustrated for the anti-Stokes spectrum with the scaling factors indicated below.
Dispersion of resonances supported in the low- dielectric film showing variation of mode frequencies vs scattering angle (or equivalently ). The data are indicated by solid dots and the solid lines are fits. The group of three higher (lower) frequency thin lines identifies the LA, TA, and Rayleigh modes associated with the Si substrate (bulk film).
Mode displacements (in plane lying in sagittal plane) and (normal to film plane) across the thick low- dielectric film supported on a Si substrate for (1TSM, 2TSM), 1.7° (1LSM), and 7.2° (2LSM). The dark solid (dashed) line refers to . Depth is measured from the top surface.
Measurements of the longitudinal sound velocity (LV) in m/s and Young’s modulus in GPa of an OSG film with nanoindentation, picosecond laser acoustics, and Brillouin light scattering. The nanoindentation and picosecond laser acoustics results were measured from thicker films and the corresponding elastic parameters computed using the Poisson’s ratio derived by Brillouin light scattering in this study.
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