Electrical Properties of (Pb, La)TiO3 Thin Films Fabricated by Multiple Cathode Sputtering

(Pb, La)TiO3 (PLT, La/Ti=0.17) thin films were prepared by multiple cathode rf-magnetron sputtering. The electrical properties of these films were investigated. The PLT thin films deposited on Pt/MgO substrates exhibited higher crystallinity and better ferroelectric properties, compared to the films deposited on Pt/SiO2/Si substrates. The hysteresis loops of the PLT films on RuO2/Ru/SiO2/Si or RuO2/Ru/MgO were narrow compared to that of film deposited on platinum electrodes. The dielectric constant of PLT films deposited at 540° C decreased with decreasing film thickness. Existence of a Pb-deficient layer near the film/substrate interface was observed by X-ray photoemission spectroscopy (XPS) analysis. By lowering the substrate temperature to 515° C, Pb re-evaporation from the substrate decreased, and ferroelectric properties were improved. By controlling the Pb/Ti incident ratio, thin films with different Pb contents of the interface layer were formed. With an increase in the Pb content near the film/substrate interface, the fatigue resistance increased.