title: Electronic structure characterization of La incorporated Hf-based high-k gate dielectrics by NEXAFS.
abstract: The electronic structures of lanthunum (La) incorporated hafnium (Hf)-based oxides (HfLaO) and their silicate (HfLaSiO) films were investigated by the Near Edge X-ray Absorption Fine Structure (NEXAFS) technique. The oxygen (O) K-edge spectra, which reflected the hybridized Hf 5d state with the O 2p orbital, were found to reveal features of the unoccupied state of the metal oxides, as well as the conduction-band edge. We also found that, while La incorporation into the Hf-based oxides simply changed the features of the conduction-band structure, subsequent thermal annealing of the La-incorporated films led to a conduction-band edge shift due to an interface silicate reaction and/or local bond rearrangement depending on the La concentration and annealing temperature. The impact of La incorporation into the Hf-based high-k materials on the electronic structure is discussed by taking into account the intrinsic nature of these metal oxides.
authors.affiliation: Toray Research Center Inc., 3-7 Sonoyama 3-Chome, Otsu, Shiga 520-8567, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Singo
authors.initials: S
authors.lastname: Ogawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kunisu
authors.forename: Junichi
authors.initials: J
authors.lastname: Tsuji
authors.forename: Koji
authors.initials: K
authors.lastname: Kita
authors.forename: Masayuki
authors.initials: M
authors.lastname: Saeki
authors.forename: Yudai
authors.initials: Y
authors.lastname: Oku
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Arimura
authors.forename: Naomu
authors.initials: N
authors.lastname: Kitano
authors.forename: Takuji
authors.initials: T
authors.lastname: Hosoi
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Shimura
authors.forename: Heiji
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D004553:Electric Conductivity; D006195:Hafnium / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D007811:Lanthanum; D006195:Hafnium