(Pb1-xLax)(ZryTi1-y)1-x/4O3, PLZT, thin films, possessing pure perovskite phase and good ferroelectric properties (Pr=21-25μC/cm) 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 ... [Show full abstract] ferroelectric properties achieved are Pr=25.6 μC/cm, Ec=47.1 kV/cm and ϵr=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.