Electrical Properties and Crystal Structure of (Ba0.5Sr0.5)TiO3 Thin Films Prepared on Pt/SiO2/Si by RF Magnetron Sputtering

Abstract

( Ba_0.5Sr_0.5)TiO₃ (BST) thin films have been prepared on Pt/SiO₂/Si substrates under various Ar/O₂ plasma conditions by the conventional rf magnetron sputtering method using a ceramic target containing excess BaO and SrO. With increasing deposition temperature, the crystallinity of the BST films abruptly increased and change of the preferred orientation was observed. At 650° C, (100)-preferred orientation was obtained. The increase of the crystallinity of films improved the dielectric constant. A 100 nm BST thin film deposited at 650° C with 50% O₂ plasma content has a dielectric constant of 725 and a leakage current density of 2.3×10^-7 A/cm² at 2.5 V. In the current-voltage curve of BST film deposited at higher substrate temperature, lower leakage current density in the low bias region and narrower flat region (hopping conduction region) were obtained.