Effect of Mn doping on the optical, structural and photoluminescence properties of nanostructured ZnO thin film synthesized by sol–gel technique

• Sol–gel ZnO:Mn films deposited by spin coating combined with water bath treatment.
• XRD, SEM and EDX were performed to study the structure, morphology, and composition.
• UV–Vis spectroscopy was used to determine the optical constants of the films.
• The photoluminescence spectra of the samples were recorded at room temperature.

Undoped and manganese doped nanocrystalline ZnO (ZnO:Mn) films were deposited onto glass substrates by a sol gel method combined with spin coating technique and water bath treatment. All of the films were annealed at 400 °C for 1 h. The effect of Mn incorporation on the structural, optical and photoluminescence (PL) properties of the ZnO films have been investigated. X-ray diffraction (XRD) analysis of the films reveals that the Mn-doped ZnO films consist of single phase ZnO with zincite structure (Card No. 36-1451) and 3 at.% Mn incorporation leads to the great improvement of the crystalline quality in Mn doped films and preferential c-axis orientation. Scanning electron microscopy (SEM) images showed that morphology and size of films were affected significantly by the Mn incorporation. Energy dispersive X-ray spectroscopy (EDX) analysis revealed the presence of Mn in the ZnO films. The doped films have improved optical transparency in the visible range. The optical band gap of the 3 at.% Mn incorporated ZnO thin film was found to be 3.43 eV. All films had a very strong blue–green emission under 390 nm excitation, for Mn doped films showed a weak band at 416 nm, a strong blue–green band at 455 nm and another weak peak at 586 nm. Indicating the potential applications of the nanostructured Mn doped ZnO thin films in nanoscale optoelectronic devices.

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