Optical properties of PbZr_xTi_1-xO₃ on platinized silicon by infrared spectroscopic ellipsometry

A method of analyzing infrared spectroscopic ellipsometry (IRSE) measurement data is proposed for lead zirconate titanate PbZr_xTi_1-xO₃ (PZT) thin films grown on Pt/Ti/SiO₂/Si substrates with x = 0.3 and 0.5. The IRSE data measured at an angle of incidence 75° for x = 0.3 and 70° for x = 0.5 are fitted by a dielectric function formula. The refractive index and extinction coefficient of PZT with x = 0.3 and 0.5 are determined in the spectral range of 2.5-12.5 μm. As the wavelength increases, the refractive index decreases, on the contrary, the extinction coefficient increases. The absorption coefficient for x = 0.5 is greater than that for x = 0.3 by a factor of 1.5. The effective static ionic charges have also been derived, which are smaller than they would be in a purely ionic material for PZT thin films.