Electronic Structure of SrTiO₃ Nanocrystallite Thin Film at High Temperature

The electronic structure and surface composition of SrTiO₃ nanocrystallite thin film at different temperature were studied by ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy, respectively. The electronic structure strongly depends on temperature and at high temperature is similar to that of single crystal. As the sample temperature falling down from high temperature, the valence band spectra of SrTiO₃ nanocrystallite thin film shift to high binding energy and become weak rapidly; an opposite process was observed when temperature rising up. This interesting phenomenon was explained on the basis of the thermodynamic equilibrium process near grain boundaries that leads to redistribution of anions and cations and forming charged grain boundaries.