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

(Ba0.5Sr0.(5))TiO3 (BST) thin films have been prepared on Pt/SiO2/Si s ubstrates under various Ar/O-2 plasma conditions by the conventional r f magnetron sputtering method using a ceramic target containing excess BaO and SrO. With increasing deposition temperature, the crystallinit y of the BST films abruptly increased and change of the preferred orie ntation was observed. At 650 degrees C, (100)-preferred orientation wa s obtained. The increase of the crystallinity of films improved the di electric constant. A 100 nm BST thin film deposited at 650 degrees C w ith 50% O-2 plasma content has a dielectric constant of 725 and a leak age,current density of 2.3 x 10(-7) A/cm(2) at 2.5 V. In the current-v oltage curve of BST film deposited at higher substrate temperature, lo wer leakage current density in the low bias region and narrower flat r egion (hopping conduction region) were obtained.