High Aspect Ratio β-Ga2O3 Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

Hsien Chih Huang, Munho Kim, Xun Zhan, Kelson Chabak, Jeong Dong Kim, Alexander Kvit, Dong Liu, Zhenqiang Ma, Jian Min Zuo, Xiuling Li

Research output: Contribution to journalArticlepeer-review


β-Ga2O3, with a bandgap of ∼4.6-4.9 eV and readily available bulk substrates, has attracted tremendous interest in the wide bandgap semiconductor community. Producing high aspect ratio β-Ga2O3 3D nanostructures without surface damage is crucial for next-generation power electronics. However, most wet etching methods can only achieve very limited aspect ratios, while dry etch usually damages the surface due to high energy ions. In this work, we demonstrate the formation of β-Ga2O3 fin arrays on a (010) β-Ga2O3 substrate by metal-assisted chemical etching (MacEtch) with high aspect ratio and sidewall surfaces with excellent quality. The etching was found to be strongly crystal orientation dependent, and three kinds of vertical structures were formed after MacEtch. The Schottky barrier height (SBH) between Pt and various MacEtch-produced β-Ga2O3 surfaces and sidewalls was found to decrease as the aspect ratio of the β-Ga2O3 vertical structure increased. This could be attributed to the different amount of oxygen lost at the surface after etching, as indicated by the XPS and TEM examination. Very little hysteresis was observed in the capacitance-voltage characteristics for the 3D Pt/Al2O3/β-Ga2O3 MOS capacitor structures, and the extracted interface trap density was as small as 2.73 × 1011 cm-2 eV-1, comparable to or lower than that for unetched planar β-Ga2O3 surfaces.

Original languageEnglish (US)
Pages (from-to)8784-8792
Number of pages9
JournalACS Nano
Issue number8
StatePublished - Aug 27 2019
Externally publishedYes


  • D
  • Schottky barrier height
  • XPS
  • high aspect ratio
  • metal-assisted chemical etching
  • β-GaO

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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