The study of wet etching on GaN surface by potassium hydroxide solution

Yung Yu Lai, Shih Chieh Hsu*, Hua Sheng Chang, Yew-Chuhg Wu, Ching Hsiang Chen, Liang Yih Chen, Yuh Jen Cheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Potassium hydroxide solution was used to etch un-doped GaN grown on the sapphire substrate at 180 and 260 °C. We illustrated the etching phenomenon in detail and probed its mechanism in the wet etching process. By multiplying the planar density and the number of dangling bonds on the N atom, we proposed the etching barrier index (EBI) to describe the difficulty degree of each lattice facet. The raking of EBI will be +c-plane > a-plane > m-plane > −c-plane > (10-1-1) plane > r-plane. Combining the EBI with SEM results, we thoroughly studied the whole etching process. We confirmed that in our research, KOH wet etching on GaN starts from the r-plane instead of the +c-plane or −c-plane, which differs from other studies. We also found that during the high-temperature etching process, there are two etching approaches. In one, the etching begins vertically from the top to the bottom, then horizontally, and finally reversely from the bottom to the top. In the other, etching pits will develop into a hexagonal hole of the sidewall of m-plane.

Original languageEnglish
Pages (from-to)3563-3572
Number of pages10
JournalResearch on Chemical Intermediates
Issue number6
StatePublished - 1 Jun 2017


  • GaN
  • KOH
  • LED
  • Wet etching


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