Structural and compositional investigation of yttrium-doped HfO2 films epitaxially grown on Si (111).

Cubic phase yttrium-doped HfO₂ (YDH) ultrathin films were grown on Si (111) substrates by molecular beam epitaxy. Thorough structural and morphological investigations by x-ray scattering and transmission electron microscopy reveal that the YDH thin films are epitaxially grown on the Si substrates with (111)_YDH∥(111)_Si and [10<OVERLINE>1</OVERLINE>]YDH∥[1<OVERLINE>1</OVERLINE>0]_Si. The interface between YDH and Si is atomistic sharp and free of interfacial layer. We have also determined the yttrium content of YDH films to be 19% by using anomalous x-ray diffraction (AXD) across Y k edge and angle resolved x-ray photoelectron spectroscopy (AR-XPS). The agreement between the AXD and AR-XPS results manifests that the incorporated Y atoms homogeneously substitute Hf atoms in the crystalline lattice and form a substitutional solid solution. [ABSTRACT FROM AUTHOR]