title: Superconductivity in transparent zinc-doped In2O3films having low carrier density.
abstract: Thin polycrystalline zinc-doped indium oxide (In2O3-ZnO) films were prepared by post-annealing amorphous films with various weight concentrationsxof ZnO in the range 0⩽x⩽0.06. We have studied the dependences of the resistivity ρ and Hall coefficient on temperatureTand magnetic fieldHin the range 0.5⩽T⩽300 K,H⩽6 Tfor 350 nm films annealed in air. Films with 0⩽x⩽0.03 show the superconducting resistive transition. The transition temperatureTcis below 3.3 K and the carrier densitynis about 1025-1026m-3. The annealed In2O3-ZnO films were examined by transmission electron microscopy and x-ray diffraction analysis revealing that the crystallinity of the films depends on the annealing time. We studied the upper critical magnetic fieldHc2(T) for the film withx= 0.01. From the slope of dHc2/dT, we obtain the coherence length ξ (0) ≈ 10 nm atT= 0 K and a coefficient of electronic heat capacity that is small compared with those of other oxide materials.
authors.affiliation: High Voltage Electron Microscopy Station, National Institute for Material Science, 3-13 Sakura, Tsukuba, Ibaraki, 305-3003, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Makise
authors.affiliation: Center for Research and Advancement in Higher Education, Kyushu University, Fukuoka 810-8560, Japan.
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Kokubo
authors.affiliation: Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 810-8560, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takada
authors.affiliation: Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 810-8560, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguti
authors.affiliation: Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 810-8560, Japan.
authors.forename: Syunsuke
authors.initials: S
authors.lastname: Ogura
authors.affiliation: Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 810-8560, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 810-8560, Japan.
authors.forename: Bunjyu
authors.initials: B
authors.lastname: Shinozaki
authors.affiliation: Advanced Technology Research Laboratories, Idemitsu Kosan Co. Ltd, Chiba 299-0293, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Yano
authors.affiliation: Advanced Technology Research Laboratories, Idemitsu Kosan Co. Ltd, Chiba 299-0293, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Advanced Technology Research Laboratories, Idemitsu Kosan Co. Ltd, Chiba 299-0293, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
keywords: annealing effect; carrier density; electrical resistivity; superconductivity; transparent thin films