Studying the effect of annealing time on structural, morphological and optical properties for AZO nanostructures

ZnO:Al films with a 1% Al/Zn atomic ratio were created using a sol-gel spin coating technique on glass substrates. The films were annealed for a duration ranging from 2:20 to 3.40 hrs. at 500 ºС. The effects of annealing time on the structural and morphological properties of AZO films were investigated utilizing X-ray diffraction (XRD), SEM and EDX to characterize samples. Scanning electron microscopy analysis showed that ZnO nanostructures with varying average sizes were developed for both as-deposited samples and annealed films. SEM revealed that both the number and size of nanosheets increased. The EDX patterns showed the right elemental traces and the oxygen ratio-mediated growth of the ZnO nanostructure on the glass substrate was visible in EDX patterns. By measuring the absorbance and transmittance spectra in the wavelength range (300-850 nm), the optical characteristics were obtained. It was found that as annealing time increases, absorbance reduces while transmission increases. The optical measurements revealed the type of transition that was a direct allowed with an average band gap energies lie between 3.76 eV and 3.12 eV with the rising of annealing time.