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In this work we present an all optical characterization of a 40 µm thick, fully relaxed,
unintentionally and only weakly n-tpye doped (n = 1.2 × 1018 cm−3) ScN film deposited by halide
vapor phase epitaxy (HVPE) on r-sapphire. We employ spectroscopic ellipsometry, Raman spectroscopy,
and photoluminescence measurements to determine intrinsic material parameters. From
spectroscopic ellipsometry we find an indirect bandgap of 1.1 eV while the fundamental direct absorption
edge is observed at 2.16 eV. A broad luminescence feature at 2.15 eV is observed, matching
this transition. In the IR-spectral region we observe a strong phonon and a weak plasmon absorption.
We precisely determine the TO phonon eigenfrequency (ωTO = 340.7 cm−1), the high
frequency dielectric constant (ε∞ = 8.4) and the static dielectric constant (εstat = 29.7). Ramanscattering
using various excitation energies shows effcient multi-phonon scattering up to 6LO when
ELaser > EG,opt, where the allowed 2LO scattering is the dominant scattering mechanism for all
excitation energies. Their characteristic parameters determined from Lorentzian line shape tting
yield ωLO = 681 cm−1 and an increased broadening and reduced asymmetry for higher LO scattering
order n. Also, an estimate for the exciton binding energy (EbX ≈ 14meV) could be derived as well
as the Born effective charges Z∗Sc = −Z∗N = 3.5.

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• In Copyright
  

  ©2024 American Physical Society

Keyword: ScN, phonon

Date published: 2024-07-17

Publisher: American Physical Society

Journal:

• Physical Review Materials (ISSN: 24759953) vol. 8 issue. 7 p. 0-0 L071601

Funding:

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4595

First published URL: https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.8.L071601

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Updated at: 2024-07-18 12:30:21 +0900

Published on MDR: 2024-07-18 12:30:21 +0900