Study on Composition Dependent Electrical Behavior in Sol-Gel Derived PZT Thin Films
Abstract
Lead zirconium titanate (PZT) films were prepared by the metallo organic deposition process on platinum coated silicon substrates. The composition was varied from Zr = 0.35 to 0.70 and annealed by the rapid thermal process. The electrical properties of these films were studied and related to film composition, annealing temperature, and thickness. The lattice constants showed compositional dependence similar to that of bulk. Morphology studies showed that the nucleation rate was in general higher than the growth rate, and thus controlled the grain sizes of the annealed films. The dielectric permittivity was found to be higher than that of bulk at Zr = 0.50. To understand the polarization behavior, the variation in the dielectric constant was measured in time and frequency domains. The behavior obeyed the Curie -von Schweidler law irrespective of processing conditions and compositions. The high field dielectric response was studied and related to domain orientations. Annealing at higher temperatures resulted in a broader distribution of domains in the tetragonal region. Room temperature conductivity measurements showed that the space charge limited conduction was the dominant mechanism. The onset of space charge depended on the Zr concentration. A maximum resistivity of 1.9times10^{11 } Omega{rm m} was found for MPB compositions. The calculated trapped electron density showed a minimum for Zr = 0.50. Thickness variation showed decreasing current density with increasing thickness.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- January 1995
- Bibcode:
- 1995PhDT........59B
- Keywords:
-
- LEAD ZIRCONIUM TITANATE;
- Engineering: Materials Science; Physics: Condensed Matter