Preparation of ZnO thin films by pulsed laser deposition

number: 
2774
إنجليزية
Degree: 
Author: 
Mohammed Ala'a Abdul Ameer
Supervisor: 
Dr. Ziad T. Al-dahan
year: 
2012
Abstract:

Zinc oxide (ZnO) and alumina-doped zinc oxide (AZO) thin films with different doping concentration have been deposited on glass substrate using pulsed laser deposition (PLD) method. A double frequency Q-switching Nd:YAG laser beam (λ=532nm, repetition rate 6 Hz and the pulse duration 10ns) has been used for the deposition process at 100oC substrate temperature and 0.4 J/cm2 laser fluense under 10-2 mbar O2 pressure. The structure properties of ZnO pure and doped with alumina were investigated by means of X-ray diffraction. As a result, it has been found that film structure did not depend on substrate doping concentration. The surface morphology of the deposits materials have been studied by using atomic force microscopes. The grain size of the nanoparticles observed at the surface depended on the doping concentration where the average grain size and rout mean square roughness increased with increasing doping concentration. UV-VIS transmittance measurements have shown that our films are transparent in the visible wavelength region, with an average transmittance of ~80% for pure ZnO and ~65% for doped ZnO films. The optical band gap of the films has been found to be 3.45 eV for pure ZnO films and 3.35 eV for 4wt. % alumina doped ZnO films. The refractive index (n) and extinction coefficient (Ke) increased as the doping concentration increased.