OPTICAL-PROPERTIES OF RF-SPUTTERED STRONTIUM SUBSTITUTED BARIUM-TITANATE THIN-FILMS

Optically active strontium substituted barium titanate (BaxSr1-xTiO3) thin films have been prepared on p-silicon and glass (Corning 7059) su bstrates by RF magnetron sputtering in a flowing Ar/O-2 atmosphere. Tr ansmittance and ellipsometric study of the films show that the refract ive index is a function of the film composition. In the W-visible tran smittance spectra, the band edge absorption of BST films shifts to low er energies when the material is in the crystalline state rather than the amorphous state. Optical band gap calculated from UV-visible trans mittance spectra increases with the increasing strontium concentration . Extinction coefficient of the films in visible region is in the orde r of 10(-3). The infrared (IR) spectra with dominant absorption bands due to Ti-O stretching, Ti-O bending and (cation)-TiO3 vibrations sugg est the formation of a single-phasic perovskite BST film in magnetron sputtering. (C) 1998 Elsevier Science S.A. All rights reserved.