Metal–oxide bilayer Raman scattering in SrTiO3 thin films

We have used a metal–oxide bilayer Raman scattering technique to study lattice dynamics in SrTiO3 thin films. The SrTiO3 thin films were epitaxially grown on a conducting metal–oxide layer which reflects the exciting laser beam so that it does not enter the LaAlO3 substrate. Raman scattering from the SrTiO3 thin films was clearly observed, including the first-order Raman peaks forbidden by the cubic symmetry in single crystals. We suggest that strain exists in the films, which changes the crystal symmetry and will affect the dielectric properties of the SrTiO3 thin films.