Pld Preparation And Optical And Electrical Properties Of Perovskite Oxide Thin Films

In this thesis, optical absorption characteristics of composite thin films were investigated based on the Mie scattering theory. Thin films of barium strontium titanates (Ba_0.5Sr_0.5TiO₃) were fabricated by pulsed laser deposition technique. The dielectric character and the nonlinear optical properties were investigated. X-ray photoelectron spectroscopy and atomic force microscopy were used to characterize the films. The nonlinear optical properties of the films were determined by using a single beam z-scan method. The main results were list as follows:(1) Optical absorption characteristics of nanometer-sized metal particles dispersed composite thin films were investigated based on the Mie scattering theory. The relationship between permittivity of Cu with wavelength was obtained. The result showed that the position of absorption peak was depended on the real part of the metal permittivity and the refractive index of the matrix when the imaginary part of the metal permittivity changed slightly.(2) Thin films of barium strontium titanates (Ba_0.5Sr_0.5TiO₃) were fabricated by pulsed laser deposition technique. X-ray photoelectron spectroscopy and atomic force microscopy were used to characterize the films. The permittivity and dielectric loss as a function of electric field are conducted on MIM capacitors by using a small ac signal of 50mV at 100 kHz. The obtained value of tunability was about 45%.(3) The nonlinear optical properties of the films were determined by a single beam z-scan method at a wavelength of 532 nm with laser duration of 55 ps. The results show that Ba_0.5Sr_0.5TiO₃ thin films exhibit a fast third-order nonlinear optical response with the nonlinear refractive index and nonlinear absorption coefficient being n₂ = 5.04×10^-6(cm²/kW) andβ= 3.59×10^-6 (m/W), respectively. The value ofχ³ is measured to be 7.06×10^-7 esu.