Reduced leakage current and enhanced ferroelectric properties in Mn-doped Bi0.5Na0.5TiO3-based thin films

Bi-0.5(Na0.76K0.2Li0.04)(0.5)TiO3 thin films were deposited on SrRuO3-coated (001)-SrTiO3 substrates by pulsed laser deposition. The effects of oxygen pressure and Mn doping on the leakage current and ferroelectric and dielectric properties were investigated. The remnant polarization and dielectric constant (at 10 kHz) of Mn-doped film deposited at 400 mtorr were measured to be 23 mu C cm(-2) and 660, respectively. The leakage current density of Mn-doped films was suppressed by more than two orders of magnitude and the polarization was considerably enhanced. The XPS results showed coexistence of Mn2+, Mn3+, and Mn4+ in doped films. Oxidation of Mn2+ to higher valence states by absorbing holes along with occupation of A-site vacancies was suggested as the possible reason for a reduced leakage current and dielectric loss in Mn-doped films.