Abstract :
Polycrystalline SrTiO3 thin films were prepared by pulsed laser deposition technique. The phonon properties and structural phase transition were studied by Raman spectroscopy. The first-order Raman scattering, which is forbidden in SrTiO3 single crystal, has been observed in the films, due to the structural distortion caused by strain effect and oxygen vacancies. The Fano-type line shape of TO2 phonon reveals the existence of polar microregions in the STO thin films. The evolution of TO2 and TO3 phonons with temperature shows the occurrence of a structural phase transition at 120 K related to the formation of polar macroregions in the films.
