Transparent conductive Al and Mn doped ZnO thin films prepared by DC reactive magnetron sputtering

ZnO films doped with Al and Mn have been prepared by DC reactive magnetron sputtering at room temperature. The electro-optical, structural properties and compositional analysis of the films have been investigated using Hall-effect measurement, optical spectroscopy, X-ray diffraction, atomic force microscope and Auger electron spectroscopy. A minimum resistivity of 3.46×10−4 Ω cm and more than 80.0% transmittance at 550 nm have been obtained. It has been observed that the percentages of Al and Mn in the films were slightly lower than that of Al and Mn mixed in the targets. It has been found that all deposited films, which contains compressive stress, have c-axis preferred orientation perpendicular to the substrate with flat and smooth surface (root-mean-square surface roughness is of the order of ∼3 nm over 5×5 μm2). In-grain scattering has been suggested to be the most probable scattering mechanism for the films (N>1020 cm−3) at room temperature.