Effects of LaNiO3 conductive buffer layer on the structural and electrical characteristics of Ba0.4Sr0.6TiO3 thin films prepared by RF magnetron sputtering

Sputter-deposited LaNiO3 (LNO) was used as a conductive buffer layer for the deposition of 80-nm-thick Ba0.4Sr0.6TiO3 (BST) thin films on Pt/Ti/SiO2/Si substrates by ri magnetron sputtering. Smooth and highly (100)-oriented perovskite films of BST were grown on the (100)-textured LNO by deposition at temperatures greater than or equal to 200 degrees C. However: a relatively rough and weakly crystallized BST film was obtained by deposition directly on Pt/Ti/SiO2/Si substrates at 500 degrees C, Satisfactory dielectric constants of 160 to 320 were achieved for films deposited on LNO at temperatures from 350 to 550 degrees C, while a low dielectric constant of 120 was obtained for the film deposited on Pt at 500 degrees C. All the films in a Pt/BST/LNO or Pt/BST/Pt capacitor configuration basically showed a similar ohmic conduction characteristic of low conductivity in low bias regime up to a transition voltage around 1-3 V, and beyond that a nonohmic conduction with current rapidly increasing against the applied bias occurred. However, the films deposited on LNO would have a more moderate nonohmic conduction than that of the film deposited on Pt.