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In this study, c-plane α-Ga2O3 films were grown by halide vapor phase epitaxy (HVPE) on high-quality α-Cr2O3/sapphire templates, and the dependence of crystalline quality on the film thickness was systematically investigated. HVPE growth was carried out under atmospheric pressure at 520 °C using GaCl and O2 as the precursors, with a growth rate of 14 µmh-1. The film thickness was varied from 0.24 to 21 µm by controlling the growth time. X-ray 2θ–ω scan and pole figure measurements confirmed that the α-Ga2O3 epitaxial layers were phase-pure single-crystalline films. Thickness-dependent X-ray rocking curve measurements and reciprocal space mapping revealed that lattice relaxation began at a thickness of approximately 0.47 µm or less and virtually completed for thicknesses of 11 µm or greater. Cross-sectional scanning transmission electron microscopy showed that dislocations were predominantly observed near the film surface and were absent at the α-Ga2O3/α-Cr2O3 interface. Etch pit density measurements yielded a low dislocation density of 5.6 × 107 cm-2 for the fully strained 0.24 µm-thick film. For the almost fully relaxed 21 µm-thick film a higher density of 3.9 × 108 cm-2 was observed. However, the value was approximately one order magnitude lower than that for an α-Ga2O3 film directly grown on a c-plane sapphire substrate under identical conditions.

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• Creative Commons BY Attribution 4.0 International
  

Keyword: Ga2O3, HVPE, Cr2O3

Date published: 2026-02-21

Publisher: AIP Publishing

Journal:

• Journal of Applied Physics (ISSN: 00218979) vol. 139 issue. 7 075302

Funding:

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

MDR DOI:

First published URL: https://doi.org/10.1063/5.0319104

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Updated at: 2026-02-18 16:30:15 +0900

Published on MDR: 2026-02-18 12:58:34 +0900