# Formation of near-vertical trenches and fins with flat {−201} sidewalls on (512) β-Ga                    <sub>2</sub>                    O                    <sub>3</sub>                    via TMAH wet etching

https://mdr.nims.go.jp/datasets/c4bc8d5e-d07a-4061-8a01-683147e91d22

## File

- [paper.pdf](https://mdr.nims.go.jp/filesets/1d6fc3f3-daec-434f-a9b8-3585fa0dd286/download) ([Detail](https://mdr.nims.go.jp/filesets/1d6fc3f3-daec-434f-a9b8-3585fa0dd286.md))

## Id

c4bc8d5e-d07a-4061-8a01-683147e91d22

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2026-09-24T00:38:02.367380Z

## Updated at

2026-09-24T00:54:18.669792Z

## Published at

2026-09-24T03:43:07.320168Z

## Doi



## First published url

https://doi.org/10.1080/14686996.2026.2726186

## Date published

2026-12-31

## Recorded date published

2026-12-31

## Resource type

journal_article

## Manuscript type

vor

## Collection



## Title

- title: |-
    Formation of near-vertical trenches and fins with flat {−201} sidewalls on (512) β-Ga
                        <sub>2</sub>
                        O
                        <sub>3</sub>
                        via TMAH wet etching
  title_type: original
  lang: en

## Description

- description: We achieved the formation of near-vertical trenches and fins with exceptionally
    flat {−201}-faceted sidewalls on (512) β-Ga2O3 substrates by crystallographic
    wet etching in 25-wt% tetramethylammonium hydroxide (TMAH). Since wet-etched (−201)
    surfaces exhibit atomically flat step-and-terrace morphologies, substrate orientations
    perpendicular to the (−201) plane and having high wet-etch rates are expected
    to enable smooth vertical trench/fin formation by wet etching alone. To identify
    such orientations, we measured the in-plane dependence of the side-etch rate on
    a (−201) substrate and found that side etching was most enhanced near the (512)
    and equivalent planes. We therefore investigated the wet-etch characteristics
    of (512) substrates. The planar etch rate increased exponentially with temperature,
    reaching 0.724 μm h−1 at 90 °C, indicating surface-reaction-limited behavior with
    an activation energy of 83.3 kJ mol−1 (0.863 eV). Near-vertical etching was achieved
    only for etching windows aligned along the [1−92] direction, parallel to the intersection
    between the (−201) and (512) planes. The developed {−201}-faceted sidewalls were
    flat and slightly inclined from the (512) surface normal by approximately 1.8°,
    in good agreement with the crystallographically estimated angle of 1.70°, suggesting
    that perfectly vertical etching could be achieved using 1.70°-miscut (512) substrates.
  description_type: abstract
  lang: und

## Creator

- name: Takayoshi Oshima
  role: author
  orcid: https://orcid.org/0000-0001-8550-9735

## Contact agent



## Publisher

organization: Informa UK Limited

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## Keyword

- subject: Ga2O3
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

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## Journal

- title: Science and Technology of Advanced Materials
  issn: '14686996'
  volume: '27'
  issue: '1'
  article_number: '2726186'

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## Funding

- identifier: JP24K01368
  funder_name: Japan Society for the Promotion of Science (JSPS), MEXT, Japan

## Instrument



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## Specimen



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## Fileset

- id: 1d6fc3f3-daec-434f-a9b8-3585fa0dd286
  filename: paper.pdf
  content_type: application/pdf
  size: 3874584
  md5: fa8eb0758a36a2f1822e920d06a8543a

## Thumbnail

fileset_id: 1d6fc3f3-daec-434f-a9b8-3585fa0dd286
filename: paper.pdf