Annealing effects of co-doping with Al and Sb on structure and optical–electrical properties of the ZnO thin films

The ZnO thin films co-doped with Al and Sb have been successfully deposited by a sol–gel spin-coating method on glass substrates and annealed at different temperature for 2 h in air. The annealing effects of different temperature on the structure and biaxial stress were characterized by X-ray diffraction. The results revealed that the annealed ZnO thin films mainly consist of ZnO with wurtzite structure, and the biaxial stress is lower during annealed at 550 °C. The annealed films have high transmittance in the visible region and show sharp absorption edges in the UV region. The optical band gap Eg values are 2.95, 3.03, 3.18 and 3.15 eV, which corresponding to the films annealed at 450, 500, 550, 600 °C, respectively. The resistivity of thin films reaches a minimum when the annealing temperature at 550 °C. The conducting mechanism is contributed to Sb substitute for Zn inducing two corresponding Zn vacancies.