Optical Properties of Nanocrystalline (Ba,Ca)TiO₃ Thin Films Grown on Pt-Coated Silicon Substrates

Abstract

Nanocrystalline (Ba_0.90Ca_0.10)TiO₃ (BCT) thin films grown on Pt/Ti/SiO₂/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 and extinction coefficient of BCT film are 2.101 and 0.0422, respectively.

Keywords:

• Nanocrystalline
• sol-gel process
• BCT thin films
• dielectric properties
• optical properties
• spectroscopic ellipsometry

PACS:

• 77.80.-e
• 78.20.Ci
• 07.60.Fs

Acknowledgments

This work is supported by the National Natural Science Foundation of China (Grant No. 10774030) and the Guangdong Provincial Natural Science Foundation of China (Grant No. 8151009001000003). The author (X.G.T) appreciates Ms. C.Y. Jing's help in the measurement of the spectroscopic ellipsometry.