Effect of low energy Ag+ ION implantation ON ZnO nanorods for enhanced visible light absorption- structural and optical analysis

Abstract Nanostructured one-dimensional ZnO nanorods (NRs) were grown on seeded borosilicate glass substrates through chemical bath deposition. The synthesised ZnO NRs were implanted with Ag + ions at low energy of 50 keV and varying fluences of 1 × 1015, 2 × 1015, 3 × 1015, 1 × 1016, and 3 × 1016 ions/cm2. The influence of injected Ag + ions was investigated on the structural and optical properties of ZnO NRs. A variation of X-ray diffraction (XRD) extracted and calculated microstructural parameters confirmed the presence of Ag+ ions on the grown ZnO NRs. XRD and Raman analysis revealed that the hexagonal wurtzite structure of ZnO was maintained, even at elevated fluences of Ag+ ions. Peak shifting to higher angles and lattice expansion were observed and attributed to substitutional doping. A red shift was observed in the absorbance spectra of Ag+ implanted ZnO NRs, suggesting a possibility of modification of the electronic structure which was confirmed through a calculation of the optical band gap and the refractive index. The energy band gap of Ag+ ion implanted ZnO NRs decreased with increase in the Ag+ ion fluence, whereas an increase was found for the calculated refractive index. The ZnO NRs implanted with 3 × 1016 ions/cm2 depicted different behaviour for structural and optical analysis, indicating a possibility of saturation of point defects and formation of different type of defects at fluences above 1 × 1016 ions/cm2. Corroboration of the structural and optical parameters demonstrate that low energy Ag + ion implantation can provide an effective and efficient approach to modify the structural and optoelectronic properties of ZnO for visible light driven photocatalytic applications.