Effects of surface condition on the work function and valence-band position of ZnSnN2

Amanda M. Shing, Yulia Tolstova, Nathan S Lewis, Harry A. Atwater

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

ZnSnN2 is an emerging wide band gap earth-abundant semiconductor with potential applications in photonic devices such as solar cells, LEDs, and optical sensors. We report the characterization by ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy of reactively radio-frequency sputtered II–IV-nitride ZnSnN2 thin films. For samples transferred in high vacuum, the ZnSnN2 surface work function was 4.0 ± 0.1 eV below the vacuum level, with a valence-band onset of 1.2 ± 0.1 eV below the Fermi level. The resulting band diagram indicates that the degenerate bulk Fermi level position in ZnSnN2 shifts to mid-gap at the surface due to band bending that results from equilibration with delocalized surface states within the gap. Brief (< 10 s) exposures to air, a nitrogen-plasma treatment, or argon-ion sputtering caused significant chemical changes at the surface, both in surface composition and interfacial energetics. The relative band positioning of the n-type semiconductor against standard redox potentials indicated that ZnSnN2 has an appropriate energy band alignment for use as a photoanode to effect the oxygen-evolution reaction.

Original languageEnglish
Article number735
JournalApplied Physics A: Materials Science and Processing
Volume123
Issue number12
DOIs
Publication statusPublished - Dec 1 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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