Abstract
Nanometer thick cubic HfO 2 doped with 19 at. % Y 2 O 3 (YDH) epitaxial films were grown on GaAs (001) using molecular beam epitaxy. Structural studies determined the epitaxial orientation relationships between the cubic YDH films and GaAs to be (001) GaAs //(001) YDH and [100] GaAs //[100] YDH . The YDH structure is strain relaxed with a lattice constant of 0.5122 nm with a small mosaic spread of 0.023° and a twist angle of 2.9°. The YDH/GaAs interface is atomically abrupt without evidence of reacted interfacial layers. From C-V and I-V measurements a 7.7 nm thick YDH film has an enhanced dielectric constant κ∼32, an equivalent oxide thickness of ∼0.94 nm, an interfacial state density D it ∼ 7 × 10 12 cm -2 eV -1 , and a low leakage current density of 6 × 10 -5 A/cm at 1 V gate bias. © 2007 American Institute of Physics.