Electrical properties of sol-gel derived La-doped PbTiO3-containing films

Abstract

Abstract A series of sol-gel derived La-doped PbTiO3-containing films was prepared on platinized Si wafers. The compositions investigated include PLT (0-28 mole % La) and PLZT (e.g., 9/65/35 and 12/80/20) films. These films were fired at temperatures ranging from 500 to 750°C. While most of the films were single-phase perovskite when fired at 700°C, lower firing temperatures (∼500°C) are sufficient to obtain crystalline PLT films, especially when the La content is more than 15 mole %. The paraelectric or ferroelectric character of the films as a function of La content is also addressed. In PLZT films, the Zr/Ti ratio affects the crystallization behavior and also the perovskite structure, i.e., either tetragonal or rhombohedral. Ferroelectric PLZT films exhibit high values of both dielectric constant (>700) and leakage current. The values of dielectric constant in the relaxor PLZT films are low, especially when compared to their bulk ceramic values (5000–10000). Paraelectric PLT films exhibit high values o...