Band gap variation of mn doped zno films prepared by spray pyrolysis technique

Undoped and manganese doped zinc oxide thin films were prepared on Si(100) substrate using spray pyrolysis technique. Nanorods having random distribution were observed on the ZnO films by scanning electron microscopy. Grazing angle X-ray diffraction and Raman spectroscopy confirmed successful growth of the wurtzite structure Zn_1-xMn_xO films without any secondary phase. From Raman spectra, the lattice defect was found to increase with increasing Mn concentration. The isothermal magnetization hysteresis measurements at room temperature show that saturation of magnetization decreased with increasing Mn concentration. Optical gap energy determined by the optical reflectance measurement showed a maximum at Mn concentration 10 mol %. It was also found that the strain parameter increases up to 10 mol % and then decreases at 15mol%. These tendencies seem to be related to the coexistence of Mn ³⁺ and Mn⁴⁺ (Mn³⁺/Mn⁴⁺) ions along with the ²⁺+ ions in the Zn_1-xMn_xO films.