Combinatorial Investigation of Structural and Optical Properties of Cation-Disordered ZnGeN2

Celeste L. Melamed, Jie Pan, Allison Mis, Karen Heinselman, Rekha R. Schnepf, Rachel Woods-Robinson, Jacob J. Cordell, Stephan Lany, Eric S. Toberer, Adele C. Tamboli

Research output: Contribution to journalArticlepeer-review

26 Scopus Citations

Abstract

Cation-disordered ZnGeN2 shows promise for application as a blue-green emitter in light-emitting devices, but more foundational work is necessary to understand structure-property relationships. In this work, we present a combinatorial exploration of the experimental phase space of wurtzite (cation-disordered) ZnGeN2 using high-throughput co-sputtering. Structure, morphology and optical properties are explored as a function of cation composition and synthesis temperature. ZnGeN2 is found to crystallize in the wurtzite structure ranging from Zn-rich to Ge-rich compositions. X-ray diffraction refinements reveal a continuous shift in cell volume with off-stoichiometry, indicating alloy-like structural behavior. The optical absorption of all films examined is lower in energy than the value predicted for cation-ordered ZnGeN2, suggesting that cation disorder is decreasing the bandgap. Additionally, the absorption threshold shifts continuously to higher energy for Ge-rich samples, consistent with bandgap shifts due to alloy-like structural behavior. Defect formation energy diagrams are calculated to help guide understanding of off-stoichiometry from a defect complex perspective. This work paves the way toward use of ZnGeN2 as a bandgap-tunable optoelectronic semiconductor.

Original languageAmerican English
Pages (from-to)8736-8746
Number of pages11
JournalJournal of Materials Chemistry C
Volume8
Issue number26
DOIs
StatePublished - 14 Jul 2020

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5K00-76385

Keywords

  • structure-property relationships
  • wurtzite

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