Effects of rare earth metal (Gd and Dy) doping on the structural and electrical properties of K0.5Bi4.5Ti4O15 thin films

摘要

K0.5Bi4.5Ti4O15 (KBTi), K0.5Bi4Gd0.5Ti4O15 (KBGdTi), and K0.5Bi4Dy0.5Ti4O15 (KBDyTi) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method to investigate the effects of doping on the structural, electrical, and ferroelectric properties. Doping with Gd- and Dy-ions clearly leads to notable improvements in the electrical and ferroelectric properties. Among the thin films, the KBGdTi thin film exhibited a low leakage current density of 1.83 x 10(-9) A/cm(2) at 100 kV/cm, a large ferroelectric polarization of 49 mu C/cm(2), and a low coercive electric field of 398 kV/cm at an applied electric field of 885 kV/cm. A fatigue endurance study showed that the switchable polarization was reduced by only 4% of the initial value after 1.44 x 10(10) switching cycles for the Gd- and Dy-doped KBTi thin films. The improvements in electrical and ferroelectric properties of the Gd- and Dy-doped KBTi thin films were explained on the basis of microstructural change, a decrease in the number of oxygen vacancies, and structural distortion caused by doping with Gd- and Dy-ions. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.