Effects of oxygen/argon pressure ratio on the structural and optical properties of Mn-doped ZnO thin films prepared by magnetron pulsed co-sputtering

Manganese doped ZnO (Zn_0.97Mn_0.3O_y) thin films were deposited by magnetron pulsed co-sputtering. The oxygen content of the films was controlled by the gas flow ratio of oxygen to argon r. The influence of r on the structure, surface morphology, optical properties and resistivity of the films was studied. A preferential growth along c axis was found in all films. As r increases, the grain size decreases, but lattice constant c, compressive lattice stress σ, and the dislocation δ density increase. The absorption edge shifts toward the shorter wavelength with r increasing, and the optical band gap is narrowed by lower r values. The resistivity of the films is also reduced by lower oxygen partial pressure. The results indicate a possibility to fabricate multifunctional devices using manganese doped ZnO thin films.