Infrared optical properties of ferroelectric 0.5BaZr0.2Ti0.8O3–0.5Ba0.7Ca0.3TiO3 thin films

0.5BaZr0.2Ti0.8O3–0.5Ba0.7Ca0.3TiO3 (BCZT50) thin films have been prepared on platinized silicon substrates by a modified sol–gel technique and proved to be well-crystallized perovskite ferroelectrics at room temperature. Optical properties of these films in the 2.5–12.5 μm wavelength range have been investigated by infrared spectroscopic ellipsometry (IRSE) at room temperature. The measured ellipsometry parameters are well fitted by Brendel oscillator dispersion formula. The optical functions and thickness of films have been uniquely extracted. As the wavelength increases, the refractive index decreases while its extinction coefficient increases. The calculated infrared absorption coefficient increases with increasing wavelength in measured wavelength range. It is greater than 1000 cm−1 for the wavelength over 11.3 μm. And it is very small and less than 100 cm−1 for the wavelength under 7.5 μm. The relatively large of the thin films reveals that it is a promising material for infrared pyroelectric detectors and arrays.