Improvement of Ferroelectric Properties in RF-Magnetron-Sputtered SrBi_2Ta_2O_9 Thin Films by Addition of Si Atoms

摘要

Si-added SrBi_2Ta_2O_9 (SBT) ferroelectric films were prepared on a Pt/Ti/SiO_2/Si(100) structure by an RF magnetron sputtering method. The films were deposited at temperatures below 100℃ to suppress the evaporation of Bi atoms and crystallized at 800℃ in air. The Si/Ta atomic ratio in the sputtering targets was changed in the range from 0 to 0.1. It was found, for the sample with the Si/Ta ratio of 0.05, that its remanent polarization (2P_r = 20 μC/cm~2) and the shape of its hysteresis loop in the polarization vs electric field (P-E) characteristic were not degraded compared to those of a pure SBT sample. It was also found that the leakage current characteristics were improved in the Si-added SBT films. Finally, the Si-added samples were annealed in oxygen ambient at 7 atm and further improvements in the leakage current and imprint characteristics were achieved.