Synthesis and characterization of undoped and Er-doped ZnO nano-structure thin films deposited by sol-gel spin coating technique

Abstract

Pure and Erbium (Er3+)-doped ZnO (Er3+ = 0.0, 1.0 and 1.5 mol%) nano-structure thin films were prepared by modified sol-gel spin coating technique. The influence of Er doping on the composition, structure, morphology, optical was examined by energy dispersive x-ray analysis (EDS), x-ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy, field emission scanning electron microscopy (FESEM). The XRD measurement and selected area electron diffraction pattern (SEDA) confirmed the hexagonal wurtzite structure of ZnO for all samples and average crystallite size is about 9.7 nm. Moreover, Both XRD and Raman spectroscopy show that the incorporation of Er3+ in ZnO matrix resulted in improved crystallinity. FESEM plane images indicated that the ZnO thin film has interconnected spherical particles with the presence of pore, whilst Er-doped ZnO films have compact and uniform morphology. Analyses of optical data point out that value of band gap of Er doped ZnO have lower values than pure film, consistent with earlier works prepared by different methods. The absorption edge shifts towards lower photon energies with increasing Erbium content.