Structural, Optical and Electrical Properties of Cu doped ZnO Thin Films Grown by RF Magnetron Sputtering: Application to Solar Photocatalysis

Abstract

RF sputtered undoped and Cu doped ZnO (CZO) thin films were deposited on unheated glass substrates using a mixed Cu2O and ZnO powders target at different Cu concentrations of 0, 1, 2, 3 and 4 wt.%. The effects of copper concentration on the structural, electrical, optical and photocatalytic properties of CZO films have been studied. From XRD and Raman spectroscopy studies, it was found that the deposited films were polycrystalline with a predominant hexagonal wurtzite structure along the c-axis perpendicular to the substrate surface. The presence of multiple interference fringes in the transmittance and reflectance spectra shows the good homogeneity of the films. All the films are highly transparent with transparency reaching 80% indicating the possibility to use these films as an optical window. The absorption tail gradually shifted towards a higher wavelength side, which resulted in the decrease of bandgap energy from 3.35 to 3.26 eV. All the sputtered films are highly conductive with a conductivity reaching 104 S.cm− 1.The effect of Cu-doping on the photocatalytic activity of ZnO thin films for the degradation of methylene blue (MB) dye was studied under sunlight irradiation and the results showed that the Cudoping provokes appreciable degradation of MB and reached a maximum for the 1 wt.% Cu doped ZnO film.

Optimal thickness and annealing temperature for enhancement of structural, optical, and photocatalytic properties of ZnO thin films

“…As observed from that figure, there is no significant loss in the photocatalytic activity after 5 cycles of reusing for ZnO (4L, 400 °C) as strong evidence for the high stability for reusing of the nanostructured ZnO thin films as photocatalysts. Table 6 shows the photocatalytic parameters of ZnO films as in the present work and also of ZnO nanoparticles from different previous researches [10,[46][47][48][49][50][51][52]. As shown in Table 6, ZnO film in the present work has the highest value of the photodegradation efficiency (97.11%) for the RO96 in the shortest period of irradiation time about 40 min with the highest rate of degradation 0.1012 min −1 compared with the previous works.…”