Preparation of Amorphous ABO3-Type Ferroelectric Materials by Sputtering and Their Physical Properties

Abstract

Thin films of amorphous ABOa-type ferroelectric materials (PbTiO₃ and LiNbO₃) are prepared by RF-sputtering on cooled substrates and their structure and electrical properties are studied. In as-sputtered PbTiO3 films, there are Pb crystallites and these films exhibit a high surface electrical conductivity of-10 (Ω·. cm)^-1. This high electrical conductivity is attributed to hopping of electrons between the Pb crystallites. When the as-sputtered films are annealed above 220°C, the surface electrical conductivity is reduced. The annealing causes a decrease in Pb crystallites in the film. This annealed film resembles roller-quenched amorphous PbTiO3. When the films are annealed above 500°C, they become Polycrystalline PbTiO3 films. As-sputtered LiNbO₃ film resembles roller-quenched amorphous LiNbO₃. They exhibit similar temperature dependence of the dielectic constants. Amorphous LiNbO₃ films exhibit high dielectric constants in film is based between the nealed above the high temperature and low measuring frequency region. Amorphous on an O-octahedral structure. The transfer of the Li atoms through O-octahedras may cause the high dielectric constant. When the films 550°C, they become polycrystalline LiNbO₃ films. LiNbO₃ openings are an nealed above 550°C, they become polycrystalline LiNbO₃ films.