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We report on the deposition by a sol-gel process of Ba0.8Sr0.2TiO3 films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 102 to 106 Hz decreases slightly and is around 400 at 104 Hz. The losses are constant in a first approximation for a 1.5 μ m thick film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained at 293 K and 10 kHz is 40 μ C/m3/K. [ABSTRACT FROM AUTHOR]

New ferroelectric Ba 0.85 Sr 0.15 TiO 3 (BST) thin films are deposited with different thicknesses (50,100, 200,280 and 400 nm) on silicon platinized substrates using spin coater machine and their morphological and structural properties are investigated. The results show that the films are well crystallized and that the perovskite phase is identified. The influence of BST film thickness on the dielectric characteristics of Au/Ba 0.85 Sr 0.15 TiO 3 /Pt capacitors are investigated and shows that the dielectric permittivity of the capacitors decreases with decreasing BST film thickness indicating the existence of a dead layer in the interfaces. Based on a series capacitor model, the dielectric permittivity and leakage current measurements, the thicknesses and dielectric permittivity of the dead layers on the Au/BST and BST/Pt interfaces are well investigated. • Au/Ba 0.85 Sr 0.15 TiO 3 /Pt thin capacitors were successfully synthesized by sol gel method. • The dielectric properties of Ba 0.85 Sr 0.15 TiO 3 thin films were investigated over a wide frequency range. • The current measurements were made on the Au/Ba 0.85 Sr 0.15 TiO 3 /Pt structure at high electric field. • The thicknesses and the dielectric permittivity of the dead layers at interfaces were investigated. [ABSTRACT FROM AUTHOR]