Hydrogen etch of GaN and its application to produce porous GaN caves

Yen Hsien Yeh*, Ying Chia Hsu, Yin Hao Wu, Kuei Ming Chen, Wei-I Lee

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Scopus citations


Although it is known that GaN tend to decompose in hydrogen environments, there has been few investigations in hydrogen etch of GaN. This study performs a systematic research on hydrogen etch of GaN under various pressures. It is observed that hydrogen atoms initially etch into GaN to form pinholes. Dislocations are usually the preferred places for initial hydrogen etch, but not all etched holes result from dislocations. When etched at low pressure and high temperature, deep vertical holes extending several microns can be formed by the hydrogen etch. However, when etch is performed at high pressure, apparent lateral etch are observed under the initial holes, leading to bollard-like GaN posts. From this systematic study, a model has been proposed to explain the vertical and the lateral etching mechanisms. With the established model, a sequential etch of GaN in hydrogen under varying pressure has been designed to successfully maintain a smooth GaN front surface, but to etch the underlying GaN to form a porous cave structure. Thick GaN films are then overgrown on such GaN layers with the hydride vapor phase epitaxy technology. It is demonstrated that the overgrown GaN thick films can self-separate from the underlying Al 2O 3 substrates.

Original languageEnglish
Title of host publicationGallium Nitride Materials and Devices VI
StatePublished - 13 May 2011
EventGallium Nitride Materials and Devices VI - San Francisco, CA, United States
Duration: 24 Jan 201127 Jan 2011

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceGallium Nitride Materials and Devices VI
Country/TerritoryUnited States
CitySan Francisco, CA


  • Gallium Nitride
  • Hydride vapor phase epitaxy
  • Hydrogen etch
  • Semiconducting III-V materials


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