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Medientyp:
E-Artikel
Titel:
Determination of anisotropic optical properties of MOCVD grown m-plane α-(Al x Ga1−x )2O3 alloys
Beteiligte:
Kluth, Elias;
Anhar Uddin Bhuiyan, A F M;
Meng, Lingyu;
Bläsing, Jürgen;
Zhao, Hongping;
Strittmatter, André;
Goldhahn, Rüdiger;
Feneberg, Martin
Erschienen:
IOP Publishing, 2023
Erschienen in:
Japanese Journal of Applied Physics, 62 (2023) 5, Seite 051001
Sprache:
Nicht zu entscheiden
DOI:
10.35848/1347-4065/acd095
ISSN:
0021-4922;
1347-4065
Entstehung:
Anmerkungen:
Beschreibung:
Abstract The anisotropic dielectric functions (DF) of corundum structured m-plane α-(Al x Ga1−x )2O3 thin films (up to x = 0.76) grown on m-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−1 by a complex Lorentz oscillator model yields the anisotropic IR active phonons E u and A 2u and 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 limits ε ∞ and the shift of the Γ-point transition energies with increasing Al content. This results in anisotropic bowing parameters for α-(Al x Ga1−x )2O3 of b ⊥ = 2.1 eV and b ∣∣ = 1.7 eV.