Selective electrochemical etching of epitaxial aluminum nitride thin film

Yongha Choi, Rakjun Choi, Jihyun Kim

    Research output: Contribution to journalArticlepeer-review

    14 Citations (Scopus)

    Abstract

    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
    Volume509
    DOIs
    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

    Keywords

    • Aluminum nitride
    • Electrochemical etching

    ASJC Scopus subject areas

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

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