Combinatorial Insights into Doping Control and Transport Properties of Zinc Tin Nitride

Angela N. Fioretti, Andriy Zakutayev, Helio Moutinho, Celeste Melamed, John D. Perkins, Andrew G. Norman, Mowafak Al-Jassim, Eric S. Toberer, Adele C. Tamboli

Research output: Contribution to journalArticlepeer-review

130 Scopus Citations

Abstract

ZnSnN2 is an Earth-abundant semiconductor analogous to the III-nitrides with potential as a solar absorber due to its direct bandgap, steep absorption onset, and disorder-driven bandgap tunability. Despite these desirable properties, discrepancies in the fundamental bandgap and degenerate n-type carrier density have been prevalent issues in the limited amount of literature available on this material. Using a combinatorial RF co-sputtering approach, we have explored a growth-temperature-composition space for Zn1+xSn1-xN2 over the ranges 35-340 °C and 0.30-0.75 Zn/(Zn + Sn). In this way, we identified an optimal set of deposition parameters for obtaining as-deposited films with wurtzite crystal structure and carrier density as low as 1.8 × 1018 cm-3. Films grown at 230 °C with Zn/(Zn + Sn) = 0.60 were found to have the largest grain size overall (70 nm diameter on average) while also exhibiting low carrier density (3 × 1018 cm-3) and high mobility (8.3 cm2 V-1 s-1). Using this approach, we establish the direct bandgap of cation-disordered ZnSnN2 at 1.0 eV. Furthermore, we report tunable carrier density as a function of cation composition, in which lower carrier density is observed for higher Zn content. This relationship manifests as a Burstein-Moss shift widening the apparent bandgap as cation composition moves away from Zn-rich. Collectively, these findings provide important insight into the fundamental properties of the Zn-Sn-N material system and highlight the potential to utilize ZnSnN2 for photovoltaics.

Original languageAmerican English
Pages (from-to)11017-11028
Number of pages12
JournalJournal of Materials Chemistry C
Volume3
Issue number42
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5J00-64356

Keywords

  • carrier density
  • direct bandgap
  • wurtzite crystal structure
  • zinc tin nitride
  • zn-sn-n

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