Abstract
Cr-doped ZnO thin films have been synthesized using sol–gel spin coating technique. The structural and optical characterizations were performed using XRD, AFM and UV–vis spectroscopy, respectively. [Display omitted]
•Zn1−xCrxO thin films were prepared via sol–gel spin coating technique.•XRD and AFM were performed to study the crystal structure, morphology and particle size.•UV–vis spectroscopy was used to determine the different optical constants.•The influence of Cr dopants on the structural and optical properties of ZnO thin films were studied.
Zn1−xCrxO thin films were grown on glass substrates by the sol–gel spin-coating technique. XRD results indicate that a ZnO single phase with a hexagonal wurtzite structure is formed. The films exhibit a preferential orientation along (002) direction in comparing with the other directions. AFM images of the films indicate that the Cr-doped ZnO films are consisted of a wrinkled network structure. The surface roughness of the films is increased with increasing Cr content. The optical band gap of Zn1−xCrxO thin films is decreased from 3.3eV to 3.2eV with the increase of Cr dopant ratio from x=0% to x=9.8% (in molar ratio). The observed red shift in optical band gap is due to s–d and p–d exchange interactions. Urbach energy, EU, values are changed inversely with optical band gaps of the films. The refractive index and optical conductivity of the films were changed with Cr content. The obtained results suggest that the structural and optical properties of ZnO films can be controlled by Cr doping.