Transparent conducting Al-doped ZnO thin films prepared by magnetron sputtering with dc and rf powers applied in combination

A newly developed Al-doped ZnO (AZO) thin-film magnetron-sputtering deposition technique that decreases resistivity, improves resistivity distribution, and produces high-rate depositions has been demonstrated by dc magnetron-sputtering depositions that incorporate rf power (dc+rf-MS), either with or without the introduction of H2 gas into the deposition chamber. The dc+rf-MS preparations were carried out in a pure Ar or an Ar+H2 (0%–2%) gas atmosphere at a pressure of 0.4Pa by adding a rf component (13.56MHz) to a constant dc power of 80W. The deposition rate in a dc+rf-MS deposition incorporating a rf power of 150W was approximately 62nm∕min, an increase from the approximately 35nm∕min observed in dc magnetron sputtering with a dc power of 80W. A resistivity as low as 3×10−4Ωcm and an improved resistivity distribution could be obtained in AZO thin films deposited on substrates at a low temperature of 150°C by dc+rf-MS with the introduction of hydrogen gas with a content of 1.5%. This article describes the effects of adding a rf power component (i.e., dc+rf-MS deposition) as well as introducing H2 gas into dc magnetron-sputtering preparations of transparent conducting AZO thin films.