Optical Properties of Nanocrystalline (Ba,Ca)TiO₃Thin Films Grown on Pt-Coated Silicon Substrates

Abstract

Nanocrystalline (Ba 0.90 Ca 0.10 )TiO 3 (BCT) thin films grown on Pt/Ti/SiO 2 /Si(100) substrates prepared by sol-gel process. The structural and surface morphology of BCT thin films has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the well-crystallized BCT thin film is perovskite phase with average grain size of 45 nm. Ellipsometric spectrum of BCT thin films annealed at 720 • C was measured in the range of wavelength from 370 to 1700 nm. Assume a four-layer model (surface roughness layer/BCT/interface/Pt) for BCT thin films on platinized silicon substrates, the optical constants spectra (refractive index n and the extinction coefficient k) of the BCT thin films were obtained. At 633 nm, refractive index nand extinction coefficient kof BCT film are 2.101 and 0.0422, respectively.