Effect of sputtering power and oxygen partial pressure on structural and opto-electronic properties of Al-doped ZnO transparent conducting oxides

This paper presents the results of electrical, optical and structural properties, along with studies of the surface morphology and cross sections of aluminium-zinc oxide (AZO) thin films. The thin films were fabricated by reactive magnetron sputtering using the two-element Zn-Al disk. The properties of the thin films prepared using different sputtering power densities and different oxygen partial pressures in the working chamber were discussed. To control the partial pressure of oxygen, a characteristic parameter of the magnetron power supply, called the circulating power, was used. The best properties of prepared AZO thin film as a transparent oxide conducting thin film were found for the film prepared using the ratio of circulating to effective power equal to 0.5. For that thin film, the electron concentration of about 6·1020 and the band gap properties (bandgap width equal to 3.14 eV, work function equal to 3.75 eV) were determined.