Effects of LaNiO_3 Conductive Buffer Layer on The Structural and Electrical Characteristics of Ba_<0.4>Sr_<0.6>TiO_3 Thin Films Prepared by RF Magnetron Sputtering

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Sputter-deposited LaNiO_3 (LNO) was used as a conductive buffer layer for the deposition of 80-nm-thick Ba_<0.4>Sr_<0.6>TiO_3 (BST) thin films on Pt/Ti/SiO_2/Si substrates by rf magnetron sputtering. Smooth and highly (100)-oriented perovskite films of BST were grown on the (100)-textured LNO by deposition at temperatures ≧200℃. However, a relatively rough and weakly crystallized BST film was obtained by deposition directly on Pt/Ti/SiO_2/Si substrates at 500℃. Satisfactory dielectric constants of 160 to 320 were achieved for films deposited on LNO at temperatures from 350 to 550℃, while a low dielectric constant of 120 was obtained for the film deposited on Pt at 500℃. 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 Lip 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.
社団法人応用物理学会の論文
1997-03-15