Characteristics of Ni-doped ZnO:Al films grown on glass by direct current magnetron co-sputtering

About 250 nm-thick Ni-doped ZnO:Al films were deposited on glass substrates at 300 K, 473 K and 673 K by direct current magnetron co-sputtering. Atomic ratio of Zn:Al:Ni in the film is 100:5:4. All the films have a ZnO wurtzite structure and grow mainly with their crystallographic c-axis perpendicular to the substrate. The films deposited at 300 K and 673 K consist of granular grains whereas the film grown at 473 K mainly has a dense columnar structure. The Ni-doped ZnO:Al film grown at 473 K has the lowest resistivity of 7.7 × 10− 3 Ωcm. All the films have an average optical transmittance of over 90% in the visible wavelength range. The absorption edge of the film grown at 473 K shifts to the shorter wavelength (blueshift) relative to those deposited at 300 K and 673 K. When the substrate temperature reaches 673 K, the Ni-doped ZnO:Al film shows a magnetization curve at room temperature, indicating that the film has a hard magnetization characteristic. The saturation magnetization is about 1 × 10− 4 T and the saturation field is about 3.2 × 105 A/m.