Self-Polarization and Migratory Polarization in Thin-Film Ferroelectric Capacitor

Electrical properties of 1- w m-thickness preferentially -oriented PZT ferroelectric films of rhombohedral composition near the morphotropic boundary prepared by RF magnetron sputtering of a ceramic target containing additionally 10 mol % lead oxide were studied. The data obtained suggests n -type conductivity due to lead oxide excess in the films. Such films were characterized by combination of a self-polarization and migratory polarization. It was shown that the self-polarization - thickness distribution was nonuniform with the most poled state localized near the bottom interface of the thin ferroelectric capacitor. The mechanism, which lies in base of such self-polarization, is related to the electron charging of the bottom interface of the structure during cooling after the high-temperature crystallization of the PZT film in the absence of the top electrode, and to bulk poling of the film by the charged interface. Heat treatment of such capacitor led to elimination of self-polarization. The obtai...