Combinatorial Synthesis of Magnesium Tin Nitride Semiconductors

Ann L. Greenaway, Amanda L. Loutris, Karen N. Heinselman, Celeste L. Melamed, Rekha R. Schnepf, M. Brooks Tellekamp, Rachel Woods-Robinson, Rachel Sherbondy, Dylan Bardgett, Sage Bauers, Andriy Zakutayev, Steven T. Christensen, Stephan Lany, Adele C. Tamboli

Research output: Contribution to journalArticlepeer-review

41 Scopus Citations

Abstract

Nitride materials feature strong chemical bonding character that leads to unique crystal structures, but many ternary nitride chemical spaces remain experimentally unexplored. The search for previously undiscovered ternary nitrides is also an opportunity to explore unique materials properties, such as transitions between cation-ordered and -disordered structures, as well as to identify candidate materials for optoelectronic applications. Here, we present a comprehensive experimental study of MgSnN2, an emerging II-IV-N2 compound, for the first time mapping phase composition and crystal structure, and examining its optoelectronic properties computationally and experimentally. We demonstrate combinatorial cosputtering of cation-disordered, wurtzite-type MgSnN2 across a range of cation compositions and temperatures, as well as the unexpected formation of a secondary, rocksalt-type phase of MgSnN2 at Mg-rich compositions and low temperatures. A computational structure search shows that the rocksalt-type phase is substantially metastable (>70 meV/atom) compared to the wurtzite-type ground state. Spectroscopic ellipsometry reveals optical absorption onsets around 2 eV, consistent with band gap tuning via cation disorder. Finally, we demonstrate epitaxial growth of a mixed wurtzite-rocksalt MgSnN2 on GaN, highlighting an opportunity for polymorphic control via epitaxy. Collectively, these findings lay the groundwork for further exploration of MgSnN2 as a model ternary nitride, with controlled polymorphism, and for device applications, enabled by control of optoelectronic properties via cation ordering.

Original languageAmerican English
Pages (from-to)8421-8430
Number of pages10
JournalJournal of the American Chemical Society
Volume142
Issue number18
DOIs
StatePublished - 6 May 2020

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-76175

Keywords

  • combinatorial synthesis
  • light-emitting diodes
  • nitride semiconductors
  • RF co-sputtering

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