Low temperature deposition of Ba0.4Sr0.6TiO3 thin films on LaNiO3-buffered electrode by rf magnetron sputtering

Sputter-deposited LaNiO3 (LNO) was used as a conductive buffer layer for the deposition of 80 nm thick (Ba0.4Sr0.6)TiO3 (BST) thin films on Pt/Ti/SiO2/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 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. A stoichiometric composition of BST films was closely reached by using the target having 30-40 mol% enrichment of Ba + Sr. The dielectric constant of the BST films notably depended on the film composition and the electrode used for deposition. The 80 nm thick films deposited on LNO containing a slight excess of Ba + Sr exhibited the largest dielectric constant of k = 150 to 310 for deposition at temperatures from 350 to 550 degrees C. All the films showed a low leakage of current < 10(-9) A/cm(2) under an applied voltage within 1-2 V. Moreover, the films deposited on LNO would have a higher resistance against the transition of conduction to the high leakage mode than that of the film deposited on Pt. (C) 1997 Elsevier Science B.V.