Thickness and Post Annealing Effects on the Structural, Optical and Dielectric Properties of Copper Oxide Thin Films رسالة ماجستير

Abstract

Abstract In this work, the thin film thickness and the post annealing effects on the structural, compositional and optical properties of copper oxide thin films are explored by means of X-ray diffraction, energy dispersive X-ray spectroscopy and ultraviolet-visible-near infrared light spectrophotometry techniques, respectively .Particularly, various thin films of copper oxide, which exhibit thicknesses in the range of 50-1000 nm were produced by the physical vapor deposition technique (thermal type) under vacuum pressure of 10-5 mbar. The films thicknesses effect on the crystalline nature and the optical transmittance, reflectance, absorbance as well as energy band gap .The dielectric spectra are determined to identify the most appropriate thickness for optoelectronic applications. It is observed that while films of thicknesses of 50 – 100 nm exhibit indirect allow electronic transition band gap, films of larger thicknesses exhibit direct allowed transition energy band gap. In addition, the analysis of the absorption coefficient spectra in the low absorption region have shown that the 1000 nm thin film has band tail . The deposited 1000 nm thin film was also annealed in vacuum at 250 °C temperature .The effect of annealing temperature on structural, optical and dielectric properties was studied using different characterization techniques. The XRD analysis confirmed the enhanced crystallinity of the 1000 nm thick sample. The optical band gaps of the annealed 1000 nm CuO thin film was measured to be 3.30 and 2.30 eV, and it exhibit no band tail after annealing. On the other hand, a dielectric constant spectrum which is carried out in the energy range of 1.1-4.0 eV exhibit decreasing values with increasing sample thickness. The imaginary part of the dielectric spectra is modeled in accordance with the hole-plasmon interaction to reveal the optical conductivity parameters. The evaluated parameters have shown that the CuO thin films can be employed as optical resonators with relativity acceptable optical conductivity suitable for visible light communications.