Structural characterization and electron-energy-loss spectroscopic study of pulsed laser deposited LiNbO₃ films on a-sapphire

Abstract

Highly c- and a-oriented LiNbO₃ films were deposited on a-sapphire substrates by pulsed laser deposition. The film microstructure and crystal orientation were studied by transmission electron microscopy, and the mechanism forming the different film orientations was interpreted in terms of the adatom energy and oxygen pressures. The electron-energy-loss functions derived from the electron-energy-loss spectra exhibit characteristic energy-loss peaks at about 7.0, 11.0, and 14.0 eV. These peaks correspond to electron transitions from the maximum density of the states in the valence band of O 2p to the split conduction band. The dielectric functions of the LiNbO₃ films were also derived from the energy-loss function.