Effects of annealing of (Ba,Sr)RuO3 bottom electrodes on the electrical properties of (Ba,Sr)TiO3 thin films

Abstract

The annealing of (Ba,Sr)RuO3 films which are structurally and chemically matched with (Ba,Sr)TiO3 films was performed in oxygen and nitrogen atmospheres in the temperature range of 600–750 °C for 30 min. The effects of annealing the (Ba,Sr)RuO3 on the physical and electrical properties of the (Ba,Sr)TiO3 films were investigated. The x-ray diffraction peak of the annealed (Ba,Sr)RuO3 film at high temperatures revealed that the (Ba,Sr)TiO3 film is thermally more stable than RuO2. The (Ba,Sr)RuO3 film under N2 annealed showed lower electrical resistivity and larger surface roughness compared with those under O2. In addition, from the sequential two-step annealing process using O2 and N2, and by reversing the annealing sequence, the electrical resistivity and the surface roughness of the (Ba,Sr)RuO3 film turned out to be reversible. The (Ba,Sr)TiO3 film on the N2 annealed (Ba,Sr)RuO3 showed a higher leakage current than that on the O2 annealed bottom electrode because rough surface can cause a high local electric field. The dielectric constant of the (Ba,Sr)TiO3 thin film increased with the annealing temperature of the (Ba,Sr)RuO3 bottom electrode regardless of the annealing atmosphere.