Structural, morphological and optical investigation of sol-gel Au-doped ZnO nanostructured thin films

Undoped and Au-doped ZnO thin films were prepared on glass substrates by sol-gel process and dip-coating technique. The effects of Au concentration (10-30 at.%) on the structural, morphological and optical properties of the... [ view full abstract ]

Undoped and Au-doped ZnO thin films were prepared on glass substrates by sol-gel process and dip-coating technique. The effects of Au concentration (10-30 at.%) on the structural, morphological and optical properties of the ZnO films were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), UV-Vis-NIR spectrometer and photoluminescence (PL) spectroscopy. XRD results showed that all films are well crystallized in a hexagonal wurtzite structure and highly c-axis oriented. Moreover, the crystal quality of the films was found to decrease with an increase in Au doping concentration and a weak diffraction peak related to Au cubic phase can also be observed at Au concentration higher than 10 at.%. FE-SEM micrographs and AFM images demonstrated that morphology and surface roughness were sensitive to Au doping concentration. UV-Vis-NIR optical spectra revealed that increasing Au doping content into ZnO films results to a significant enhancement in the transparency of the films. Photoluminescence measurements at room temperature put into evidence the presence of two intense bands at 373.6 and 385 nm in the UV spectra and four very weak emission bands in the visible region. All these emissions were found to be dependent upon the Au content.