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Description:

A systematic investigation of the optical properties of β-, α-, and κ-phase gallium
oxide (Ga2O3) polymorphs is conducted by UV–vis spectrophotometry through
the Swanepoel method and temperature-dependent photoluminescence. Using
the same approach and apparatus allows similarities and differences between
these three phases to be directly established. Differences between polymorphs are
observed, including refractive indices of 1.89 (β), 2.00 (α), and 1.85 (κ) and optical
bandgaps of 4.99 eV (β), 5.32 eV (α), and 4.87 eV (κ). In the luminescence studies,
four emission peaks in each polymorph are revealed, located at different energies
in the UV (3.1–3.9 eV), blue (2.7–3.0 eV), and green (2.2–2.6 eV) regions, with
causes attributed to self-trapped holes, donor–acceptor pair transitions involving
Ga and O vacancies (VGa, VO), Ga─O divacancies (VGaþ VO), O interstitials (Oi),
and H impurities (VGa–nH, Hi, Ho). In this systematic study, unique optical
properties of the different Ga2O3 polymorphs are highlighted and it is warned that
the commonly practiced analogy to β-Ga2O3 can lead to misinterpretations.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Ga2O3

Date published: 2025-02-12

Publisher: Wiley

Journal:

• physica status solidi (b) (ISSN: 03701972) vol. 262 issue. 8 2400615

Funding:

• Ministero dell’Istruzione, dell’Università e della Ricerca 2022A4AN2F
• Engineering and Physical Sciences Research Council EP/W524670/1
• Engineering and Physical Sciences Research Council EP/V034995/1

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1002/pssb.202400615

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Updated at: 2025-08-18 16:30:52 +0900

Published on MDR: 2025-08-18 16:21:28 +0900