ELECTRICAL-PROPERTIES AND CRYSTAL-STRUCTURE OF (BA0.5SR0.5)TIO3 THIN-FILMS PREPARED ON PT/SIO2/SI BY RF MAGNETRON SPUTTERING

Abstract

(Ba0.5Sr0.(5))TiO3 (BST) thin films have been prepared on Pt/SiO2/Si substrates under various Ar/O-2 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 degrees 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 degrees C with 50% O-2 plasma content has a dielectric constant of 725 and a leakage,current density of 2.3 x 10(-7) A/cm(2) 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.