Optical and electronic properties of Mn-doped ZnO films synthesized by RF magnetron sputtering

Zn1-xMnxO films are prepared by radio frequency (RF) magnetron sputtering method. The wurtzite ZnO crystal can be well retained up to a Mn composition of 6.7% and doped Mn ions substituted into Zn sites of ZnO host lattice. All the samples show high transparency over the wavelengths from 450 to 800 nm. Optical transmittance study showed an increase in the bandgap (E-g) with increase in Mn atomic fraction x following E-g=3.26+1.43x eV. Furthermore, the midgap absorption around 420 nm (3 eV) in Mn doped ZnO films suggest that there are impurity levels created by doped Mn ions. The room temperature resistivities of the samples show an increase with the increase of Mn content, which indicates that the doped element is at the status of deep levels.