We investigated AlxTiyO/n-GaAs(001) metal-insulator-semiconductor (MIS) structures, in which Alx TiyO thin films as high-k dielectric were obtained by atomic layer deposition, utilizing alternative supply of Al2O3 and TiO2 precursors. Using X-ray photoelectron spectroscopy, we obtained atomic composition ratios of Al and Ti in the Alx TiyO thin films. It is shown that the breakdown field of the AlxTiyO increases with increase in the Al composition.
Based on temperature-dependent current density-voltage (J -V) characteristics, we elucidated that dominant conduction mechanisms are thermionic emission, Fowler-Nordheim tunneling, and Poole-Frenkel conduction, depending on the composition. From the Poole-Frenkel current, we estimated dielectric constants of the AlxTiyO, which increase with decrease in the Al composition. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)