Effect of post-annealing on the structure and dielectric property of La2Ti2O7 thin film

La2Ti2O7 thin films were grown on Si (100) substrates by using pulsed laser deposition method. The effect of post-annealing on the structural and dielectric properties of the films at different temperatures was studied by using X-ray diffraction, atomic force microscopy and synchrotron infrared transmission spectroscopy. The results show that the as-deposited thin film is amorphous and annealing thin film is crystallized into monoclinic structure. The infrared spectrum reveals that the annealing can significantly increase the dielectric constant. The as-deposited thin film has a low dielectric constant attributed to the loss of some phonon modes, especially the low frequency mode. This indicates post-annealing has an important influence on the dielectric property of La2Ti2O7 thin film.