Features of Thin Films of Barium Strontium Niobate Probed by Brillouin Light Scattering

Brillouin spectra of barium strontium niobate thin films SBN-75 on sapphire substrate were measured in different scattering geometries. The spectral shape of the LA mode in the backscattering and 90A geometries were analyzed. The results are compared with the corresponding measurements on a relatively thick barium strontium niobate film and a bulk crystal. It is shown that a broad anomalously large peak in the vicinity of 25 GHz appears in the Brillouin scattering in SBN-75 films on a sapphire substrate after annealing. Spectral and scanning electron microscopy experimental studies were carried out (to identify the nature of this peak).