Electrical properties and crystal structures of (Ba,Sr)TiO↓(3) films and BaRuO↓(3) bottom electrodes prepared by sputtering

摘要

(Ba,Sr)TiO↓(3) (BST) films were synthesized on BaRuO↓(3) (BRO) using radio-frequency magnetron sputter deposition. Conductive (~1 mΩcm) BRO layers of (110) texture were produced at a deposition temperature T↓(d)=400℃, about 200 ℃ lower than that of SrRuO↓(3) The BST (100 nm) deposited on the BRO showed a (110) preferred orientation and crystallization formation at temperatures as low as 200℃. An interfacial layer and the local epitaxial growth of BST on BRO layers within columnar grains were confirmed by high-resolution transmission-electron microscopy studies. Uniform I-V characteristics (I＜1×10↑(-7) A/cra2) for bias voltages in the range 0.0-3.0 V of all the BST films deposited within T↓(d)= 300-500℃ were observed. The dielectric constants of the BST films (e.g., e↓(r) = 300 at T↓(d) = 400℃) are considerably higher than those generally achievable for the same Td by using Pt bottom electrodes. The dependence of the annealing atmosphere (N2 and O↓(2)) of the dielectric constants was studied and attributed to a diffused BST/BRO interfacial layer which is semiconductive in a reduced state and insulating in an oxidized state.#1998 American Institute of Physics.S0003-6951(98)01910-X