Selective electrochemical etching of epitaxial aluminum nitride thin film

Yongha Choi, Rakjun Choi, Jihyun Kim

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Aluminum nitride (AlN) has an ultra-wide bandgap energy of 6.2 eV and is resistant to chemical etching owing to its high chemical stability, making it intractable in the device fabrication process. We developed a facile method of electrochemical (EC) etching of a high-quality AlN epitaxial layer, where both spatial selectivity and a controllable etch rate were achieved. Underneath porous metal electrodes, the lateral etch rate increased with the increasing external anodic bias, from 400 nm/min at 5 V to 700 nm/min at 15 V. Nonporous metal electrodes protected the AlN from etching in hot H3PO4, enabling the spatial selectivity. The high EC etch rate is attributed to the enhanced hole-assisted oxidation at the interface between the AlN and the etchant. The etch pit formed by EC etching exhibited an inverse hexagonal pyramid structure with {1 0 –1 −1} face. As an alternative to dry etching, our method can be applied to the low-damage patterning of AlN with a controllable etch rate.

Original languageEnglish
Article number145279
JournalApplied Surface Science
Publication statusPublished - 2020 Apr 15

Bibliographical note

Funding Information:
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) ( 20173010012970 and 20172010104830 ) and National Research Foundation of Korea ( NRF-2018R1D1A1A09083917 ).

Publisher Copyright:
© 2020


  • Aluminum nitride
  • Electrochemical etching

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces


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