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

Abstract

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- κ tetragonal zirconia phase coexists with the most commonly observed monoclinic, increasing the κ 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. © 2008 American Institute of Physics.