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

Abstract

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 1h. 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 3at.% 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 3at.% Mn incorporated ZnO thin film was found to be 3.43eV. All films had a very strong blue–green emission under 390nm excitation, for Mn doped films showed a weak band at 416nm, a strong blue–green band at 455nm and another weak peak at 586nm. Indicating the potential applications of the nanostructured Mn doped ZnO thin films in nanoscale optoelectronic devices.