Tunable optoelectronic and ferroelectric properties in Sc-based III-nitrides

DOI PDF 被引用文献13件
  • Siyuan Zhang
    Department of Materials Science and Metallurgy, University of Cambridge 1 , 27 Charles Babbage Road, CB3 0FS Cambridge, United Kingdom
  • David Holec
    Department of Physical Metallurgy and Materials Testing 2 , Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria
  • Wai Yuen Fu
    Department of Materials Science and Metallurgy, University of Cambridge 1 , 27 Charles Babbage Road, CB3 0FS Cambridge, United Kingdom
  • Colin J. Humphreys
    Department of Materials Science and Metallurgy, University of Cambridge 1 , 27 Charles Babbage Road, CB3 0FS Cambridge, United Kingdom
  • Michelle A. Moram
    Department of Materials Science and Metallurgy, University of Cambridge 1 , 27 Charles Babbage Road, CB3 0FS Cambridge, United Kingdom

書誌事項

公開日
2013-10-04
DOI
  • 10.1063/1.4824179
公開者
AIP Publishing

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説明

<jats:p>Sc-based III-nitride alloys were studied using density functional theory with special quasi-random structure methodology. ScxAl1−xN and ScxGa1−xN alloys are found to be stable in hexagonal phases up to x ≈ 0.56 and x ≈ 0.66, respectively, above which rock-salt structures are more stable. Epitaxial strain stabilization can prevent spinodal decomposition up to x ≈ 0.4 (ScxAl1−xN on AlN or GaN) and x = 0.27 (ScxGa1−xN on GaN). The increase in Sc content expands the in-plane lattice parameter of ScxAl1−xN and ScxGa1−xN alloys, leads to composition- and strain-tunable band gaps and polarization, and ultimately introduces ferroelectric functionality in ScxGa1−xN at x ≈ 0.625. A modified Becke-Johnson exchange-correlation potential was applied to study the electronic structures, which yielded band gaps comparable to those from hybrid functional calculations, yet in a much shorter computational time. The alloys were found to retain wide band gaps, which stay direct up to x = 0.25 (ScxAl1−xN) and x = 0.5 (ScxGa1−xN). The band gaps decrease with increasing x for ScxAl1−xN, in which the Sc-3d states dominate at the conduction band minimum and lead to flat electron dispersion at the Γ point. Conversely, the band gaps increase with increasing x for ScxGa1−xN (up to x = 0.5), in which Sc-3d states do not contribute to the conduction band minimum at the Γ point.</jats:p>

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