부산대학교 도서관

We report on the deposition by a sol-gel process of Ba0.8Sr0.2TiO3 and Ba0.9Sr0.1TiO3 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 μm thick BST(80/20) 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 on BST(90/10) at 293 K and 10 kHz is of 149 μC/m3/K. The best dielectric and pyroelectric properties (tgδ = 0.006 at 1 MHz, tunability = 30%, γ = 340 μC/m2/K) were obtained on the 400 nm BST(90/10) film. Work is in progress to characterize the piezoelectric and photovoltaic properties of our BST films. [ABSTRACT FROM AUTHOR]