Interfacial characteristics and dielectric properties of Ba0.65Sr0.35TiO3 thin films

Ba0.65Sr0.35TiO3 (BST) thin films were deposited on Pt/Ti/SiO2/Si substrates by radio frequency magnetron sputtering technique. X-ray photoelectron spectroscopy (XPS) depth profiling data show that each element component of the BST film possesses a uniform distribution from the outermost surface to subsurface, but obvious Ti-rich is present to BST/Pt interface because Ti4+ cations are partially reduced to form amorphous oxides such as TiOx (x<2). Based on the measurement of XPS valence band spectrum, an energy band diagram in the vicinity of BST/ Pt interface is proposed. Dielectric property measurements at 1 MHz reveal that dielectric constant and loss tangent are 323 and 0.0095 with no bias, while 260 and 0.0284 with direct current bias of 25 V, furthermore, tunability and figure of merit are calculated to be 19.51% and 20.54, respectively. The leakage current density through the BST film is about 8.96 x 10(-7) A/cm(2) at 1.23 V and lower than 5.66 x 10(-6) A/cm(2) at 2.05 V as well as breakdown strength is above 3.01 x 10(5) V/cm. (C) 2007 Elsevier B.V. All rights reserved.