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Your search keyword '"Bunjyu Shinozaki"' showing total 2 results
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2 results on '"Bunjyu Shinozaki"'

1. Superconductivity in transparent zinc-doped In2O3 films having low carrier density

Author

Kazumasa Makise, Nobuhito Kokubo, Satoshi Takada, Takashi Yamaguti, Syunsuke Ogura, Kazumasa Yamada, Bunjyu Shinozaki, Koki Yano, Kazuyoshi Inoue and Hiroaki Nakamura

Subjects
transparent thin films, carrier density, electrical resistivity, annealing effect, superconductivity, Materials of engineering and construction. Mechanics of materials, TA401-492, Biotechnology, TP248.13-248.65
Abstract

Thin polycrystalline zinc-doped indium oxide (In2O3–ZnO) films were prepared by post-annealing amorphous films with various weight concentrations x of ZnO in the range 0≤x ≤0.06. We have studied the dependences of the resistivity ρ and Hall coefficient on temperature T and magnetic field H in 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 temperature Tc is below 3.3 K and the carrier density n is about 1025–1026 m−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 field Hc2 (T) for the film with x = 0.01. From the slope of dHc2 /dT, we obtain the coherence length ξ (0) ≈ 10 nm at T = 0 K and a coefficient of electronic heat capacity that is small compared with those of other oxide materials.

Published
2008
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2. Weak localization and percolation effects in annealed In2O3-ZnO thin films

Author

S. Ezaki, Koki Yano, T. Asano, Kazumasa Makise, K. Hidaka, Hiroaki Nakamura, and Bunjyu Shinozaki

Subjects
Weak localization, Materials science, Magnetoresistance, Condensed matter physics, Annealing (metallurgy), Scanning electron microscope, General Physics and Astronomy, Inelastic scattering, Thin film, Fick's laws of diffusion, Sheet resistance, lcsh:Physics, lcsh:QC1-999
Abstract

We have investigated the temperature T and magnetic field H dependences of the sheet resistance R□ of thin (In2O3)0.975-(ZnO)0.025 films with different resistivities and carrier densities prepared by postannealing in air at various annealing temperatures Ta. Regarding the magnetoconductance Δσ(H) ≡ 1/R□(H) − 1/R□(0) of films with large values of sheet resistance R□, agreement between weak localization theory and the data cannot be obtained for any value of the localization length L in (T)=Dτ in (T), where D and τin are the diffusion constant and inelastic scattering time, respectively. Taking account of the inhomogeneous morphology confirmed by Scanning Electron Microscopy (SEM) observation, we introduced the effective sheet resistance R□eff given by R□eff = α × R□meas., where the strength of reduction factor α is less than unit, α ⩽ 1. Using a suitable value of α(Ta), we successfully fitted the theory to data for Δσeff(H, T), regarding Lin2(T) as a fitting parameter in the region 2.0 K⩽T ⩽ 50 K. It was confirmed that the rate 1/τin(T) is given by the sum of the electron-electron and electron-phonon inelastic scattering rates.

Published
2011

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