Annealing induced effect on the physical properties of ion-beam sputtered 0.5 Ba(Zr0.2Ti0.8)O-3-0.5 (Ba0.7Ca0.3)TiO3-delta ferroelectric thin films
Abstrakt
This work reports thermal annealing induced effect on the structural, optical, chemical and ferroelectric properties of ion-beam sputtered lead-free ferroelectric 0.5 Ba(Zr0.2Ti0.8)O-3 - 0.5(Ba0.7Ca0.3)TiO3-delta (0.5BZT-0.5BCT) thin films. X-ray diffraction studies reveal that the tetragonality increases with the annealing temperature (T-a), while photoluminescence and X-ray photoelectron spectroscopy studies confirm that this effect is associated with the annihilation of the oxygen vacancies as well as changes in the Ba2+ coordination.
The films annealed at 750 degrees C show a remarkable remnant polarization of P-r = 45.0 mu C/cm(2), with a coercive field of 32 kV/cm. The temperature dependence of the spontaneous polarization of the 0.5BZT-0.5BCT film reveals a mean field behavior of the polarization and the fatigue study reveals that P-r only decreases 3% after passing 10(9) cycles.
Therefore the high remnant polarization and its high P-r stability make these films as promising candidates for memory applications.