Effect of Calcinations Temperature on ZnO:Co Nanostructured Thin Films Prepared By Sol – Gel Method.

Abstract

Nanostructured ZnO thin films were developed on medical-glass substrates using a sol gel dip coating process and calcinated at various temperatures (350, 450, and 550 C°). The impact of Co doping and effect temperature calcination on the structural, optical and electrical properties of ZnO:Co nanostructured thin films were investigated using XRD, SEM, Hall effect, and UV-Visible spectra measurements. Both nanostructured films have hexagonal-wurtzite crystals composition according to XRD analysis with the average crystallite sizes of ZnO:Co nanostructured thin films are of (26.7-102.1) nm. The FESEM findings show that the undoped ZnO thin film has the smoothest and more regular surface compared to the doped ZnO films, indicating that both films with nanoscale ZnO particles. The average transmittance of all films is about 69–91 % in the visible range and the band gap energy decreased from 3.283 to 3.205 eV with increase of temperature calcination. The Hall impact indicates that all thin films are n-type and the electrical conductivity increase from (12.4-16.2) in the ZnO:Co thin films. This one of the outstanding property of ZnO thin films, both undoped and doped with cobalt, enables the fabrication of transparent electrodes for flat panel displays, metal-insulator-semiconductor diodes, and solar cells.