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Author So, Hyeon Seob ♦ Park, Jun-Woo ♦ Jung, Dae Ho ♦ Ko, Kun Hee ♦ Lee, Hosun
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ ABUNDANCE ♦ ANNEALING ♦ ANTIMONY ♦ CARRIER MOBILITY ♦ CARRIERS ♦ DEPOSITION ♦ DIELECTRIC MATERIALS ♦ DOPED MATERIALS ♦ ELLIPSOMETRY ♦ GRAIN SIZE ♦ HALL EFFECT ♦ OPTICAL PROPERTIES ♦ SPUTTERING ♦ TEMPERATURE RANGE 0273-0400 K ♦ THIN FILMS ♦ TIN OXIDES
Abstract We investigated the optical properties of amorphous and crystalline antimony (Sb)-doped tin dioxide (SnO{sub 2}) thin films grown using the co-sputtering deposition method at room temperature. We used undoped and Sb-doped (8 wt. %) SnO{sub 2} targets. Varying the relative power ratio of the two targets, we controlled the Sb-composition of the SnO{sub 2}:Sb thin films up to 2.3 at. % of Sb contents. Through annealing, the as-grown amorphous SnO{sub 2}:Sb thin films were transformed to crystalline thin films. Dielectric functions were obtained from the measured ellipsometry angles, Ψ and Δ, using the Drude and parametric optical constant models. We determined the absorption coefficients and optical gap energies of the SnO{sub 2}:Sb thin films from the dielectric functions. We found increasing optical gap energy with increasing Sb composition. Increases in the Drude tail amplitudes, a signature of free carrier concentrations, were found in annealed, crystalline thin films with increasing Sb composition. The increase in the optical gap energy with increasing Sb composition was mainly attributed to the Burstein-Moss effect. Using Hall effect measurements, we obtained Hall carrier concentrations (N{sub Hall}) and electron Hall mobilities (μ{sub Hall}). The carrier concentrations and mobilities increased from 2.6 × 10{sup 19 }cm{sup −3} and 1.0 cm{sup 2}/(V s) to 2.0 × 10{sup 20 }cm{sup −1} and 7.2 cm{sup 2}/(V s), respectively, with increasing Sb contents. This result suggests that the nominally undoped SnO{sub 2} films are unintentionally n-type doped. Assuming that the N{sub Hall} and optical carrier concentrations (N{sub opt}) were the same, we obtained the effective masses of the SnO{sub 2}:Sb thin films with increasing Sb compositions. The effective masses of the SnO{sub 2}:Sb thin films increased from 0.245 m{sub 0} to 0.4 m{sub 0} with increasing Sb doping contents, and the nonparabolicity of the conduction band was estimated. We discussed the relation between the optical (μ{sub opt}) and Hall (μ{sub Hall}) mobilities as a function of Sb contents and grain sizes.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-08-28
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 118
Issue Number 8


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