The effect of film thickness on the structural, optical and electrical properties of ZnO thin films deposited by ultrasonic spray deposition

Zinc oxide (ZnO) thin films were deposited by ultrasonic spray deposition at different film thicknesses at 420 degrees C. The ZnO solution was obtained with a concentration of 0.1 mol.l(-1), it was deposited on glass substrate at various times. The structural, optical and electrical properties of ZnO thin films were studied at different film thicknesses. In the results, the XRD shows that the ZnO thin films having a hexagonal structure with (002) and (101) diffraction peaks, which were observed in al deposited films. The minimum crystallite size of (002) and (101) phases are 43.6 nm for 460 nm and 32.2 nm for 350 nm, respectively. The optical transmission of ZnO thin film is about 80% approach the wavelength of 800 nm in the visible region. The optical band gap energy of ZnO thin films was decreased from 3.26 to 2.91 with increasing the film thickness from 250 to 460 nm. The highest Urbach energy was obtained at 460 nm. The ZnO thin films have an electrical conductivity was increased from 0.19 to 6.74 (Omega .cm)(-1) when film thickness increases from 250 to 460 nm. The best crystalline structure, optical band gap and electrical conductivity are achieved at 460 nm.