Improvement on ferroelectric properties of (Pb_1-xLa_x)(Zr_yTi_1-y)_1-x/4O₃ thin films by using metallic Ru as intermediate layers

Abstract

(Pb_1-xLa_x)(Zr_yTi_1-y)_1-x/4O₃, PLZT, thin films, possessing pure perovskite phase and good ferroelectric properties (P_r=21-25μC/cm²) were successfully deposited on Pt-coated Si substrates, using SrRuO₃ perovskite as buffer layer. Precoating a metallic Ru-layer on Pt(Si) substrates prior to the deposition of SrRuO₃ buffer layer further improved thin films' electrical properties. The optimum ferroelectric properties achieved are P_r=25.6 μC/cm², Ec=47.1 kV/cm and ε_r=1,204. Analyses of elemental depth profiles using secondary ions mass spectroscopy (SIMS) indicate that the significant outward diffusion of Ti-and Si-species has been markedly suppressed at the presence of metallic Ru-layer. The effective suppression on the interdiffusion between the SrRuO₃ buffer layer and the subsequently deposited PLZT is presumed to be the main factor resulting in better ferroelectric properties for PLZT thin films.

Key Words:

• ferroelectric thin film
• PLZT
• SrRuO₃/Ru buffer layer