摘要
<p>Nanometer thick cubic HfO<sub>2</sub> doped with 19 at. % Y<sub>2</sub>O<sub>3</sub> (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)<sub>GaAs</sub>/ /(001)<sub>YDH</sub> and (100)<sub>GaAs</sub>/ /(100)<sub>YDH</sub>. 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 <span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black"><span style="font-family:"新細明體","serif"">κ</span></span></span></span>~32, an equivalent oxide thickness of ~0.94nm, an interfacial state density D<sub>it</sub>~7X10<sup>12</sup> cm<sup>−2</sup> eV<sup>−1</sup>, and a low leakage current density of 6X10<sup>-5</sup> A/cm<sup>2</sup> at 1V gate bias.</p>