09:15 〜 09:30
▲ [15a-2L-2] Electrical properties of 100-oriented (1-x)BiFeO3-x(Bi0.5,K0.5)TiO3 thin films on LaNiO3 electrode
キーワード：Thin films,ferroelectricity,piezoelectricity
(1-x)BiFeO3–x(Bi0.5K0.5)TiO3 (BF-BKT) system is one of the candidate of lead-free piezoelectric ceramics because it is reported that BF-BKT ceramics have large piezoelectric constant (d33=370pm/V). This result is encouraging for the improvement of piezoelectric constant of Bi-base perovskite ferroelectric thin films. In this study, we investigate the phase development for crystallization process and electrical properties of BF-BKT thin films grown on (100) oriented LaNiO3/Si.
0.6BF-0.4BKT films were deposited by rf-sputtering method. 0.6BF-0.4BKT ceramic disk with 10% excess Bi prepared by conventional ceramic process was used as a target. The films were grown on (100) LaNiO3 (LNO)/Si substrates under the process pressure of 1 Pa with an Ar:O2 ratio of 4:1. The thickness of the films was fixed as ~240 nm. The XRD profiles of 0.6BF-0.4BKT thin films deposited at the substrate temperature between 475 °C and 575 °C. While all the films crystallized in perovskite phase, the integrated diffraction intensities of 200 peaks of the films are highest at 505 °C and the lattice constant decreases with increasing growth temperature. It was also found that the films deposited at higher temperature have the deficiencies of Bi3+ and K+. The polarization-voltage (P-V) hysteresis loop of the films was measured at room-temperature. Although the films deposited above 540 °C do not show the hysteresis behavior, the ferroelectricity is observed for the films deposited at below 505 °C. It appears this is also caused by the evaporation of Bi3+ and K+ at higher deposition temperature. In this study, we would like to discuss the electrical properties of 0.6BF-0.4BKT thin films.
0.6BF-0.4BKT films were deposited by rf-sputtering method. 0.6BF-0.4BKT ceramic disk with 10% excess Bi prepared by conventional ceramic process was used as a target. The films were grown on (100) LaNiO3 (LNO)/Si substrates under the process pressure of 1 Pa with an Ar:O2 ratio of 4:1. The thickness of the films was fixed as ~240 nm. The XRD profiles of 0.6BF-0.4BKT thin films deposited at the substrate temperature between 475 °C and 575 °C. While all the films crystallized in perovskite phase, the integrated diffraction intensities of 200 peaks of the films are highest at 505 °C and the lattice constant decreases with increasing growth temperature. It was also found that the films deposited at higher temperature have the deficiencies of Bi3+ and K+. The polarization-voltage (P-V) hysteresis loop of the films was measured at room-temperature. Although the films deposited above 540 °C do not show the hysteresis behavior, the ferroelectricity is observed for the films deposited at below 505 °C. It appears this is also caused by the evaporation of Bi3+ and K+ at higher deposition temperature. In this study, we would like to discuss the electrical properties of 0.6BF-0.4BKT thin films.