Electrical Properties of Single Crystalline CeO2High-k Gate Dielectrics Directly Grown on Si (111)

We have grown epitaxial single crystalline CeO 2 directly on Si (111) by molecular beam epitaxy. Metal-insulator-semiconductor (MIS) capacitors were fabricated to evaluate electrical properties of CeO 2 films. By eliminating an interfacial layer, equivalent oxide thickness ( EOT ) as small as 0.38 nm was obtained for a CeO 2 physical thickness of 5 nm. The dielectric constant ( ε ) was calculated to be ε ∼52, which is two times larger than the value reported for bulk (polycrystalline) CeO 2 ( ε ∼26). Enhancement of ε is probably attributable to the anisotropy of the single crystalline CeO 2 and/or the lattice distortion of CeO 2 directly grown on Si. A leakage current density of ∼ 1 A/cm 2 was obtained at an equivalent electrical field of 5 MV/cm for the CeO 2 MIS capacitors, which is much smaller than the expected value for SiO 2 capacitors with the same EOT . It is revealed that single crystalline CeO 2 is promising as an alternative gate dielectric.