Influence of Cu incorporation on structural, optical, and electronic structure of ZnO thin films deposited by laser ablation

Abstract

Pristine and Cu-doped ZnO thin films with 3 wt%, 5 wt% & 7 wt% Cu concentrations were deposited by pulsed laser deposition (PLD) to observe the effect of incorporation of Cu in ZnO lattice towards their structural, optical and electronic structural properties. Structural investigations were carried out using X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), and Field Emission Scanning Electron Microscopy (FESEM). Optical studies were performed using UV–Visible (UV–Vis), Photoluminescence, and RAMAN spectroscopies. The electronic structure of the films was studied using X-Ray absorption spectroscopy (XAS). All the films are oriented along (002) plane with wurtzite hexagonal symmetry, confirmed from XRD results. The optical band gap energy of ZnO thin films decreases from 3.26 eV to 3.0 eV with increasing Cu concentration from 0 to 7 wt% respectively. The various structural defects were confirmed from PL spectrums. The variation in the hybridization of O 2p states with Cu doping concentration is understood by XAS study.