Electrical and structural properties of multicomponent transparent conducting oxide films prepared by co-sputtering of AZO and ITO

Multicomponent transparent conducting oxide (TCO) films were deposited on glass substrates by co-sputtering of Al-doped ZnO (AZO) and Sn-doped In ₂O ₃ (ITO) targets. Changes in the electrical and structural properties of the films were investigated as a function of the power on ITO target at a constant AZO power. The addition of limited amounts of ITO (cation ratio of [In]/[Al + Zn + In + Sn], δ < 0.28) resulted in deteriorations in the electrical properties of TCO films compared to the pure AZO film. The improvement of electrical conductivity was observed for the films having δ > 0.34, where the resistivity decreased with increasing δ. Hall-effect measurements showed that there is a noticeable increase in mobility at a certain value of ITO power. X-ray diffraction analysis revealed that the transition of microstructure from polycrystalline to amorphous phase is corresponding to the increase in mobility. In addition, the introduction of H ₂ (2%) into the sputtering ambient was found to increase the carrier concentration of AZO–ITO films and promote the transition into amorphous phase. Both effects resulted in further improvement of the electrical conductivity of the TCO films.