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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
Abstract The anisotropic dielectric functions (DF) of corundum structured m -plane α -(Al x Ga 1− x ) 2 O 3 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 2 u 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 Ga 1− x ) 2 O 3 of b ⊥ = 2.1 eV and b ∣∣ = 1.7 eV.  more » « less
Award ID(s):
2019753 2231026
PAR ID:
10436049
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
Japanese Journal of Applied Physics
Volume:
62
Issue:
5
ISSN:
0021-4922
Page Range / eLocation ID:
051001
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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