Heterostructural interface engineering for ultrawide-gap nitrides from first principles: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mrow><mml:mi>Ta</mml:mi><mml:mi mathvariant="normal">C</mml:mi><

Epitaxial lattice matching is an important condition for the formation of coherent interfaces with low defect densities. However, lattice-matched substrates with the same crystal structure as the active layer are often not available, suggesting opportunities for utilizing heterostructural interfaces. For example, at high <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:mi>Al</a:mi></a:math> contents that are interesting for ultrawide-gap applications in power electronics, <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><d:msub><d:mi>Al</d:mi><d:mi>x</d:mi></d:msub><d:msub><d:mi>Ga</d:mi><d:mrow><d:mn>1</d:mn><d:mo>−</d:mo><d:mi>x</d:mi></d:mrow></d:msub><d:mrow><d:mi mathvariant="normal">N</d:mi></d:mrow></d:math> semiconductor alloys in the (0001) orientation of the wurtzite (wz) structure become lattice-matched to (111)-oriented rocksalt (rs) <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><h:mrow><h:mi>Ta</h:mi><h:mi mathvariant="normal">C</h:mi></h:mrow></h:math> substrates. To predict the expected interface atomic structures under different synthesis conditions, we perform high-throughput density-functional-theory calculations, using an algorithm for systematic sampling of the possible stacking sequences of the atomic layers on the in-plane hexagonal lattice. The approach considers octahedral, tetrahedral, and prismatic coordination motifs, and is generally applicable for the modeling of commensurate rs/wz heterostructural interfaces. Our results provide guidance for synthesis control of substrate-film bonding and the polarity of ultrawide-gap <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><l:msub><l:mi>Al</l:mi><l:mi>x</l:mi></l:msub><l:msub><l:mi>Ga</l:mi><l:mrow><l:mn>1</l:mn><l:mo>−</l:mo><l:mi>x</l:mi></l:mrow></l:msub><l:mrow><l:mi mathvariant="normal">N</l:mi></l:mrow></l:math> alloys on <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><p:mrow><p:mi>Ta</p:mi><p:mi mathvariant="normal">C</p:mi></p:mrow></p:math> substrates. Published by the American Physical Society 2024