Subwavelength photocathodes via metal-assisted chemical etching of GaAs for solar hydrogen generation

Keorock Choi, Kyunghwan Kim, In Kyu Moon, Jangwon Bang, Jungwoo Oh

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

MacEtch allows subwavelength-structured (SWS) texturing on the GaAs surface without compromising crystallinity. The current density increases greatly, which is directly due to the reduction in the reflectance. Photons absorbed under reduced light reflectance are less affected by the charge recombination arising from crystal defects. The catalytic metal remaining after MacEtch serves as a catalyst for water splitting and increases the open-circuit potentials of the SWS GaAs photocathodes. The SWS GaAs not only amplifies the absorption of light, but also improves the collection of deeply generated photons at long wavelengths. The solar-weighted reflectance (SWR) of SWS GaAs is 6.6%, which was much lower than the 39.0% of bare GaAs. The light-limited photocurrent density (LLPC) increased by approximately 90% and the tafel slope improved as etching progressed. The external quantum efficiency was as high as 80%, especially at long wavelengths, after MacEtch. SWS GaAs photocathodes fabricated using MacEtch significantly reduce reflectance and recombination loss, thereby improving the key performance of PEC for hydrogen production. This technology can fully utilize the high absorption rate and carrier mobility of GaAs and is applicable to various photoelectric conversion device performance enhancements.

Original languageEnglish
Pages (from-to)15367-15373
Number of pages7
JournalNanoscale
Volume11
Issue number32
DOIs
Publication statusPublished - 2019 Aug 28

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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