Full orientation control of epitaxial MoS2 on hBN assisted by substrate defects

Fu Zhang, Yuanxi Wang, Chad Erb, Ke Wang, Parivash Moradifar, Vincent H. Crespi, Nasim Alem

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Inversion asymmetry in two-dimensional materials grants them fascinating properties such as spin-coupled valley degrees of freedom and piezoelectricity, but at the cost of inversion domain boundaries if the epitaxy of the grown two-dimensional (2D) layer, on a polar substrate, cannot adequately distinguish what are often near-degenerate 0 and 180 orientations. We employ first-principles calculations to identify a method to lift this near degeneracy: the energetic distinction between eclipsed and staggered configurations during nucleation at a point defect in the substrate. For monolayer MoS2 grown on hexagonal boron nitride, the predicted defect complex can be more stable than common MoS2 point defects because it is both a donor-acceptor pair and a Frenkel pair shared between adjacent layers of a 2D heterostack. Orientation control is verified in experiments that achieve ∼90% consistency in the orientation of as-grown triangular MoS2 flakes on hBN, as confirmed by aberration-corrected scanning/transmission electron microscopy. This defect-enhanced orientational epitaxy could provide a general mechanism to break the near-degeneracy of 0/180 orientations of polar 2D materials on polar substrates, overcoming a long-standing impediment to scalable synthesis of single-crystal 2D semiconductors.

Original languageEnglish (US)
Article number155430
JournalPhysical Review B
Volume99
Issue number15
DOIs
StatePublished - Apr 29 2019

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Point defects
Epitaxial growth
Defects
defects
Substrates
epitaxy
point defects
Piezoelectricity
Boron nitride
inversions
Aberrations
piezoelectricity
Monolayers
flakes
Nucleation
boron nitrides
Single crystals
Semiconductor materials
Transmission electron microscopy
valleys

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

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abstract = "Inversion asymmetry in two-dimensional materials grants them fascinating properties such as spin-coupled valley degrees of freedom and piezoelectricity, but at the cost of inversion domain boundaries if the epitaxy of the grown two-dimensional (2D) layer, on a polar substrate, cannot adequately distinguish what are often near-degenerate 0 and 180 orientations. We employ first-principles calculations to identify a method to lift this near degeneracy: the energetic distinction between eclipsed and staggered configurations during nucleation at a point defect in the substrate. For monolayer MoS2 grown on hexagonal boron nitride, the predicted defect complex can be more stable than common MoS2 point defects because it is both a donor-acceptor pair and a Frenkel pair shared between adjacent layers of a 2D heterostack. Orientation control is verified in experiments that achieve ∼90{\%} consistency in the orientation of as-grown triangular MoS2 flakes on hBN, as confirmed by aberration-corrected scanning/transmission electron microscopy. This defect-enhanced orientational epitaxy could provide a general mechanism to break the near-degeneracy of 0/180 orientations of polar 2D materials on polar substrates, overcoming a long-standing impediment to scalable synthesis of single-crystal 2D semiconductors.",
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Full orientation control of epitaxial MoS2 on hBN assisted by substrate defects. / Zhang, Fu; Wang, Yuanxi; Erb, Chad; Wang, Ke; Moradifar, Parivash; Crespi, Vincent H.; Alem, Nasim.

In: Physical Review B, Vol. 99, No. 15, 155430, 29.04.2019.

Research output: Contribution to journalArticle

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