Electrical properties of epitaxial Lu- or Y-doped La2O3/La2O3/Ge high-k gate-stacks

Electrical properties of epitaxial La2O3/germanium (Ge) structures can be significantly improved by using epitaxially grown Lutetium(Lu)- or Yttrium(Y)-doped La2O3 passivation layers. For the metal-insulator-semiconductor (MIS) devices, hysteretic nature of capacitance-voltage (C-V) characteristics becomes negligibly small and the interface trap density (Dit) is estimated to be less than 1012 cm−2 eV−1 at around the midgap. We discuss a possible mechanism of the improvement of the electrical properties.