Effect of bottom electrodes on the structural and electrical characteristics of lanthanum doped lead titanate thin films

Abstract

Ferroelectric Pb_0.90La_0.15TiO₃ (PLT15) thin films were deposited by sol-gel method on Pt, Pt/Si, ruthenium oxide (RuO₂)/Si and RuO₂/Pt/Si bottom electrodes. X-ray diffraction, and micro-Raman spectroscopy techniques were used for structural characterization of these films. PLT15 films deposited on RuO₂ electrodes show (100) preferred orientation of growth and result in larger crystallites. Films on Pt electrode exhibited higher dielectric constant (1300 at 100 kHz) and high values of P_m, P_r values, 68 and 46 µ C/cm² respectively. AC field dependence of dielectric permittivity at sub-switching fields was fitted using the Rayleigh law. The reversible polarization components estimated from the CV and quasi-static hysteresis measurements for films on Pt/Si (24%), was larger than that of Pt (11%) bottom electrodes. The observed results were correlated with the domain wall pinning at the disturbed film-electrode interface.