الفهرس 
Theoretical BackgroundOnly 14 pages are availabe for public view
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Abstract
ZnO thin films were deposited on glass substrate at room temperature (RT) by using pulsed laser deposition (PLD) such that the target was ZnO nanoparticles prepared by microwave method. The fabricated ZnO thin films and ZnO nanoparticles were annealed for 2h at 300, 350, 400, 450 and 500 oC in air. The effects of annealing temperatures on the structural, optical and electrical properties of annealed ZnO thin films and ZnO nanoparticles were investigated by XRD, FTIR spectra, transmission electron microscope (TEM), scanning electron microscope (SEM), transmittance spectra, photoluminescence (PL), dc conductivity and ac conductivity. The XRD of the annealed films and nanoparticles reveal the presence of polycrystalline ZnO with hexagonal wurtzite structure. Using Scherrer equation, the average grain size of annealed films and nanoparticles were found to be 5.22–10.61nm and 25.7–36.4 nm, respectively. The presence of ZnO thin films and nanoparticles is confirmed from the FTIR spectra and the values of optical phonon frequency (υo) were found to be 1.26-1.58 x 1013 Hz and 1.26 - 1.3 x 1013 Hz, respectively. The TEM image of annealed ZnO thin film at 4000C shows ZnO nanobelts with average grain diameter 12nm but the TEM image of annealed nanoparticles at 4000C shows ZnO nanorods with average grain diameter 39nm and grain length 388nm. The SEM image of annealed ZnO thin film at 4000C shows rough surface and the crystalline grains in the spherical shape. On the other hand, The SEM image of annealed ZnO nanoparticles at 4000C shows a large quantity of flower-shaped structures. from the UV-Vis spectra, the optical band gap energy of ZnO thin films is found to be in the range 2.95-3.32 eV but the vacancy energy level of ZnO nanoparticles was found to be 2.25 - 2.37 eV. The PL spectra of ZnO thin films shows strong UV, violet, blue and green emissions however, the PL spectra of ZnO nanoparticles shows that all the samples emits strong UV and very weak violet, blue and green emissions. The electrical conductivity shows that all samples are semiconductor. The calculated activation energy for the films was found to be 0.093-0.168 eV. On the other hand, the activation energy for the nanoparticles was found to be 0.35-0.791 eV. The ac conductivity studies of ZnO nanoparticles reveal that the ac conductivity increased with the annealing temperature because the average grain size and oxygen vacancies increased with the annealing temperature while these parameters improve with the increasing of temperature. The increase of ac conductivity with the temperature indicates that the mobility of charge carriers is increased. The annealed ZnO thin film at 4000C for 2h is the best film to be use it as transparent conductive electrodes for various applications, particularly, solar cells and organic light emitting diode (OLED). Where, the transmission of the film is about 90% in the visible range, the activation energy is about 0.093 eV and the electrical conductivity at room temperature is 382.7Ω -1 m -1.