MICROSTRUCTURE DEPENDENCE OF ELECTRICAL-PROPERTIES OF (BA0.5SR0.5)TIO3 THIN-FILMS DEPOSITED ON PT SIO2/SI/

Stoichiometric (Ba0.5Sr0.5S)TiO3 (BST) thin films with various thickne sses have been prepared on Pt/SiO2/Si substrates using conventional rf magnetron sputtering method with a ceramic target containing excess B aO and SrO. With increasing film thickness, the grain size of the BST films gradually increased. It was observed that the dielectric constan t increased from 348 to 758 when grain size increased from 32 to 82 nm in BST films deposited at 600 degrees C. The decrease of dielectric c onstant in thinner BST films was attributed to the initial low dielect ric constant layer and small grain size. In the current-voltage curves for BST films, higher leakage current densities and narrower flat reg ions (hopping conduction region) in the low bias field were obtained w ith increasing grain size. (C) 1996 American Institute of Physics.