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Description:

We demonstrated heated tetramethylammonium hydroxide (TMAH) etching (25 wt. % concentration, at 90 °C) as an effective post-dry-etch treatment for improving dry-etched trench profiles on (010) β-Ga2O3. This treatment successfully converted rough, tapered dry-etched trench sidewalls into smooth, vertical ones, except for trenches oriented close to the [201] direction, where side etching was most pronounced. In particular, when trenches were oriented along the [102] direction, the exposed vertical sidewalls became exceptionally flat, indicating the preferential development of (⁠-201) facets. At the same time, the initially convex trench bottoms were planarized, yielding a well-defined box-like cross-sectional profile. Importantly, both the (⁠-201) sidewalls and the (010) bottom surface underwent only minimal material removal, consistent with the very low etch rates of these crystallographic planes. Together with its known ability to alleviate dry-etch damage, TMAH etching can, therefore, be regarded as a highly effective post-treatment for dry-etched fins and trenches on the (010) plane.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Ga2O3, TMAH

Date published: 2026-02-01

Publisher: AIP Publishing

Journal:

• AIP Advances (ISSN: 21583226) vol. 16 issue. 2 025145

Funding:

• Japan Society for the Promotion of Science JP24K01368

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

MDR DOI:

First published URL: https://doi.org/10.1063/5.0305647

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Updated at: 2026-02-25 12:30:03 +0900

Published on MDR: 2026-02-25 10:40:30 +0900