Lanthanum rare earth element doped zinc oxide nanostructures: synthesis, structural, morphological, topographical and optical investigations

Abstract

Undoped ZnO and ZnO nanostructures doped with 2 at. % and 4 at. % lanthanum (La)-doped ZnO, deposited onto glass substrates by using spray pyrolysis technique, are investigated. The impact of La doping on the structural, morphological, topographical and optical properties is researched by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray spectroscopy (EDXS), ultraviolet-visible spectrophotometer (UV-vis) and Fourier transform infrared spectroscopy (FTIR), respectively. XRD patterns have shown polycrystalline within wurtzite structure. The structural parameters, such as lattice constant, crystallite size and additional lattice parameters are derived from XRD data, with an increase in La doping, the crystallites size is decreased from 37 nm to 35 nm. The surface morphology is investigated to show a change with increasing La doping. The RMS values rise from 6.22 nm for undoped ZnO to 749.1 pm and 163.2 pm for ZnO doped with 2% and 4% La, respectively. EDXS studies have showed the existence of Zn, O and La elements in La-doped ZnO nanostructures. UV-vis spectrophotometer measurements have displayed an excellent transmittance in the visible region, averaging 80-90% and bandgap energies (E-g) in the range, 3.25-3.27 eV.