The Effects of Mn Doping on the Structural and Optical Properties of ZnO

Zn1-xMnxO(x = 0.00, 0.01, and 0.05, respectively) was synthesized by using solid state reaction method. The structural properties were characterized by using X-ray diffraction and scanning electron microscopy. Optical properties were investigated by UV-visible spectroscopy. X-ray diffraction patterns indicate that all samples have hexagonal wurtzite structure without any impurity phases. The diffraction intensity increases and the peak position shifts to a lower 2 theta angle with Mn concentration. The lattice parameters a and c, the volume of unit cell increase with Mn content indicating that Mn2+ ions go to Zn2+ ions in ZnO lattice. The grain size increases with Mn doping while the microstrain and dislocation density decrease. UV-vis spectra of the samples show that undoped ZnO sample has an energy band gap E-g of 3.34 eV. The optical study indicates a red shift in the absorbance spectra and a decrease in the band gap E-g with Mn content. This decrease of band gap may be attributed to the influence of dopant ions. The morphology and grain distribution of ZnO samples were analysed by scanning electron microscopy. The particle sizes are higher in doped samples when compared to the undoped sample and the surface roughness increases with Mn content. The grains are closely, densely packed and pores/voids between the grains increase with Mn content.