Very high-κ ZrO2 with La2O3 (LaGeOx) passivating interfacial layers on germanium substrates

Thin La2O3 (LaGeOx) passivating layers combined with ZrO2 caps form a chemically stable bilayer gate stack on Ge with good electrical properties. The most important observation is that a higher-kappa tetragonal zirconia phase coexists with the most commonly observed monoclinic, increasing the kappa value of the oxide to about 32, thus benefiting the measured stack equivalent oxide thickness. This indicates that the ZrO2/La2O3 combination could be a promising candidate gate stack for Ge metal-oxide-semiconductor devices in terms of scalability.