The aluminum oxide (Al2O3) nanoparticles thin  films has been prepared via UV-irradiation methods using metal salts (aluminum nitrate Al(NO3)3) with different  thickness (150 , 200, 300 , and 400) and measuring structural and optical properties.

The structure of the (Al2O3) nanoparticles thin films was tested with X-Ray showed that have six main diffraction features corresponding to (111), (311), (222), (400), (511) and (440) planes . The results of atomic force microscopy ( AFM )  indicated that all films have grain size about 25.97-65nm .

The optical band gap energy was decreased by the increase of thickness from (5.19-4.68) eV then used aluminum oxide as gas sensor.