Preperation, characterization and photocatalytic activity of magnesium doped zinc oxide thin films

Abstract

Zinc Oxide (ZnO) and Magnesium doped Zinc Oxide (MZO) thin films have been Prepared and their structural, optical, surface morphological, and electrical properties together with the photo catalytic activity have been studied. The thin films with different doping concentration of Mg varied between 0 to 8 at% were deposited on glass substrate by sol-gel dip coating technique. The scanning electron microscopy (SEM) images of the films showed uniform deposition throughout the film. With the incorporation of increasing amount of Mg dopant, the particle size changes and increase the porosity (0.4 to 2.55%) and the roughness of surface. Structural characterizations reveal high crystallinity of the ZnO thin film possessing hexagonal wurtzite structure. Crystallinity of the film is found to be increasing with the increasing amount of Mg doping concentration. The electrical resistivity of the thin film is found to be increased (6.17 to 9.1 k ohom-m) with the incorporation of Mg content. The optical transmittance spectrum of the films showed a very good transmittance, within the visible wavelength region for the undoped which farther increases with the amount of Mg dopant upto 90%. The band gaps of the films are found to be varied (3.36 to 3.73) with the amount of doping. The MZO thin films exhibited highly enhanced photo-catalytic activity comparing to pure ZnO thin films under UV illumination. The higher surface area of the thin film due to the roughness, and porosity is one of the causes for the enhanced photo catalytic activity of MZO than that of pure ZnO films. The nano-crystalline MZO thin films with high optical transparency together with high resistivity prepared by sol-gel dip coating technique would be a better choice for many optoelectronic devices and can be found application in water purification and environment cleaning process.