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Creators/Authors contains: "Goldhahn, Rüdiger"

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  1. ; ; ; ; ; ; ; (, Japanese Journal of Applied Physics)
    Abstract The anisotropic dielectric functions (DF) of corundum structuredm-planeα-(AlxGa1−x)2O3thin films (up tox= 0.76) grown onm-plane sapphire substrate by metalorganic CVD have been investigated. IR and visible–UV spectroscopic ellipsometry yields the DFs, while X-ray diffraction revealed the lattice parameters (a,m,c), showing the samples are almost fully relaxed. Analysis of the IR DFs from 250 to 6000 cm−1by a complex Lorentz oscillator model yields the anisotropic IR active phononsEuandA2uand the shift towards higher wavenumbers with increasing Al content. Analyzing the UV DFs from 0.5 to 6.6 eV we find the change in the dielectric limitsε∞and the shift of the Γ-point transition energies with increasing Al content. This results in anisotropic bowing parameters forα-(AlxGa1−x)2O3ofb⊥= 2.1 eV andb∣∣= 1.7 eV. 
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