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Title: Determination of anisotropic optical properties of MOCVD grown m-plane α-(Al x Ga 1−x ) 2 O 3 alloys

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 limitsεand 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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Award ID(s):
2019753 2231026
Publication Date:
Journal Name:
Japanese Journal of Applied Physics
Page Range or eLocation-ID:
Article No. 051001
DOI PREFIX: 10.35848
Sponsoring Org:
National Science Foundation
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