Structural and optical properties of pure and Al doped ZnO nanocrystals

Pure and Al doped zinc oxide (ZnO) were prepared by co-precipitation method. The dopant concentration [Al/Zn in atomic percentage (wt%)] was varied from 0 to 3 wt%. Structural characterisation of the samples performed with XRD and SEM–EDAX confirmed that polycrystalline nature of samples containing ZnO nanoparticles of size in the range of 97–47 nm. UV–Vis studies showed that the absorbance peaks, observed in the wavelength range of 800–250 nm, decreased with the increase in dopant concentration indicating widening of the band gap. The calculations of band gap (analyzed in terms of Burstein–Moss shift) from the reflectance showed an increase from 3.37 to 3.49 eV with increasing Al concentration. (author)