Spectroscopic ellipsometry study of the dielectric response of Au-In and Ag-Sn thin-film couples |
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Authors: | A.A. Wronkowska A. Wronkowski K. Kukliński M. Senski ?. Skowroński |
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Affiliation: | Institute of Mathematics and Physics, University of Technology and Life Sciences, S. Kaliskiego 7, 85-796 Bydgoszcz, Poland |
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Abstract: | Optical properties and phase composition of In-Au and Sn-Ag ultra-thin films grown by sequential evaporating and co-depositing of metals in a vacuum were investigated combining X-ray diffraction and spectroscopic ellipsometry methods. The atomic concentration ratios of bilayer and co-deposited samples were the same, i.e. In(Sn):Au(Ag) = 1:2. The XRD patterns indicated creation of AuIn, AuIn2, Au3In2, Au9In4 and Ag3Sn intermetallic compounds at room temperature. The effective complex dielectric functions of the composite layers, , were determined from ellipsometric quantities Ψ and Δ measured in a photon energy range of 0.6-6.5 eV. The free-carrier parameters (unscreened plasma frequency and free-carrier damping) and optical resistivity were evaluated using a semiclassical Drude-Lorentz model of the effective dielectric function. There was noticed a distinct influence of phase composition and surface morphology on the optical constants and conductivity of the samples: ρop changed from approximately 15 μΩ cm to 37 μΩ cm for Ag-Sn structures, composed of β-Sn and Ag3Sn phases, and from 21 μΩ cm to 83 μΩ cm for Au-In multiphase system. Lower resistivity demonstrated diffusive layers formed after deposition of an In(Sn) thin film on the noble metal underlayer. |
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Keywords: | 66.30.Pa 78.66.Bz 78.20.Ci 07.60.Fs 78.70.Ck |
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