A comparative study on the nanocrystalline ZnO thin films prepared by ultrasonic spray and sol⿿gel method

Nanocrystalline ZnO thin films are deposited through two different chemical methods: (i) the films prepared by ultrasonic spray with 0.1 M and (ii) dip-coating from zinc acetate complex solutions with 0.5 M, the films obtained at different temperatures. The XRD analyses indicated that ZnO films have nanocrystalline hexagonal structure with (0 0 2) preferential orientation and the maximum crystallite size value of 103 nm measured from the films prepared by dip-coating. UV⿿vis measurement indicated that all films are transparency in the visible region. The optical band gap increased with decreasing of the Urbach tail energy indicating that the increase in the transition tail width and decrease of the defects, respectively.