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 journalArticlepeer-review

28 Scopus citations


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
Issue number15
StatePublished - Apr 29 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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