META 2021, META'12

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Influence of Mn doping on structural and optical properties of ZnO nano thin films synthesized by sol-gel technique

Last modified: 2015-07-04


Undoped and Mn-doped ZnO samples with different percentage of Mn content (1, 5 and 10 at l %) were synthesized by a dip-coating sol-gel method. We have studied the structural, chemical and optical properties of the samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–VIS spectroscopy. The XRD spectra show that all the samples are hexagonal wurtzite structures. We note that doping favors c-axis orientation along planes (002). Up to 5at% of Mn doping level, c-axis lattice parameter shifts towards higher value with the increase of manganese content in the films. The expansion of the lattice constant of ZnO-Mn indicates that Mn is really doped into the ZnO. The SEM investigations of all samples revealed that the crystallites are of nanometer size. The surface quality of the ZnO-Mn film increases with Mn doping but no significant changes of the grain size is observed from SEM images. The transmittance spectra show that the transparency of all the samples is greater than 85%. We note, also, that a small doping (1%) lowered the refractive index while the thickness of the layers and the gap increases. However, raising the proportion of Mn beyond 5%, practically the same values of index and gap than pure ZnO are found.