Substrate temperature effect on optical property of ZnO thin films

Abstract

The transparent conducting ZnO thin films were deposited on glass substrate by ultrasonic spray technique. The optical, electrical and structural properties of the ZnO thin films were studied as a function of the substrate temperatures in the range of 300 to 400 °C. The as deposited film exhibit a hexagonal structure wurtzite and (101) oriented. The value of grain size G = 28 nm is measured of ZnO film at 350 °C. All the films having high transparency in the visible region, the band gap energy decreased from 3.44 to 3.29 eV with increasing the substrate temperatures from 300 to 400 °C, respectively according to the Burstein-Moss effect (blue shift of Eg). The Urbach energy decreased reaching to minimum at 350 °C; indicating to decrease of the defects. The electrical resistivity of the films at 350 °C is 50 Ω.cm. A systematic study on the influence of the substrate temperatures on the optical, electrical and structural properties of ZnO thin films deposited by ultrasonic spray has been reported.