aMinistry of Education, General Directorate of Babylon Education, Babylon, Iraq.

^bMinistry of Education, Anbar Education Directorate, Al-Qaim Education Department, Iraq.

^cMinistry of Education, General Administration of Education, Governorate of Babylon, Iraq.

^dDepartment of Radiation and Sonar Technologies, Alnukhba University College, Iraq.

^eBasic science Division, Faculty of Agricultural Engineering, Baghdad University, Iraq.

^fDepartment of Physics, College of Education, Mustansiriyah University, Iraq.

ZnO thin films having different thicknesses (300, 400 and 500) nm were deposited by spray pyrolysis method (SPM). XRD analysis indicate that the deposited films have hexagonal wurtzite structure and display a strong peak at (002) plane. The effects of thicknesses on crystallite size, stress and strain are investigated. The thicknesses effect on film surface topography parameters such as roughness, particle size and Root mean square of grains are calculated. Atomic Force Microscopy (AFM) confirm that the distribution grains size appears nanostructure and homogeneous in all films. RMS increases from 1.54 nm to 3.98 nm with thicknesses 500 nm. The surface roughness increases from 1.33 nm to

3.30 nm. Transmittance was detecting to be atop 80% in visible region. The bandgap energy increased from 2.83 eV to 3.75 eV with thickness elevation.