抄録
To investigate the mechanism of the polarization fatigue of ferroelectric thin films, we analyzed the relationship between the crystalline defects of electrode/ferroelectric interface and fatigue characteristics of PZT thin films. Pt/PZT/Pt thin films were prepared by the chemical solution deposition method, and conditions of Pt/PZT interface were analyzed by TEM-EDX analysis, thermally stimulated current methods and I-V Properties. The PZT layers of about 30nm near the top Pt electrodes became an n-type due to the oxygen vacancies and they formed the contact similar to the top electrode of Pt/n-type PZT/p-type PZT. Because the height and width of the Schottky barrier in the Pt/PZT interface had reduced with the increase of the fatigue, this band structure was observed in the electric field where the Fowler-Nordheim currents were lower than usual. This is considered to be caused by the increase of crystalline defects near the interface due to the impressing of the bipolar pulse. This phenomenon was observed quantitatively by TSC analysis, and the TSC peak of 490K became larger with the increase of the fatigue. The activation energy of the TSC peak was 0.8ev and the defect density was 2.5×1019/cm3, which is consider to be produced by Pb defects.
