Skip to content

Considerations for Utilizing Sodium Chloride in Epitaxial Molybdenum Disulfide

Summary

This experimental materials study compares alkali-free epitaxial monolayer MoS₂ on sapphire with NaCl-assisted metal–organic chemical vapor deposition (MOCVD) growth. While NaCl can greatly enlarge domains, the authors show it can also introduce spatial heterogeneity in optical and electronic response, nanoscale MoS₂ particulates, loss of epitaxy, and >1% tensile strain that suppresses photoluminescence and degrades transistors relative to alkali-free growth under matched conditions.

Alkali promoters are widely used in TMD growth recipes; this paper documents that domain-size gains can coexist with defect populations that hurt optoelectronic uniformity.

Methods

  • Growth: MOCVD of monolayer MoS₂ on sapphire, comparing alkali-free runs to NaCl-assisted growth (abstract).
  • Benchmarking: Side-by-side comparison under the same growth conditions where the abstract emphasizes fair contrast between routes.
  • Characterization (as claimed in abstract): Metrics tied to domain size, strain, photoluminescence (PL), field-effect transistor performance, and microscopy-level evidence for nanoscale MoS₂ particle density (4 ± 0.7 μm⁻² scale in abstract) and interface/epitaxy behavior.

The matched-conditions design isolates the role of NaCl rather than confounding changes in temperature or precursor flow.

Findings

  • NaCl increases monolayer MoS₂ domain size dramatically (abstract: ~20× vs alkali-free under their conditions).
  • Trade-offs: NaCl coexists with strong optical/electronic heterogeneity across large films, variable growth rates, epitaxy loss, and elevated nanoscale MoS₂ particle counts on the surface (abstract).
  • Strain and optoelectronics: NaCl-assisted films carry >1% tensile strain in domains; PL drops ~20× versus alkali-free counterparts, and transistor metrics worsen accordingly (abstract).

The takeaway for process engineers is to treat NaCl as a two-edged modifier: it can coarsen morphology while introducing residual particulates and strain that undermine device metrics.

ACS Applied Materials & Interfaces includes growth recipes, statistical distributions of domain sizes, and supplementary microscopy establishing particulate counts cited in the abstract.

Confirm the DOI from the publisher landing page if your toolchain requires a resolver link in addition to volume and page span metadata.

Limitations

The note is not a ReaxFF/atomistic simulation paper—claims are from growth and device/optical characterization. Full protocol details (precursor flows, temperatures, times) should be read in the article and SI; DOI was not in normalized metadata—confirm from the publisher landing page if needed.

Relevance to group

2DCC / Penn State growth science for TMD electronics—complements atomistic TMD work elsewhere in the corpus even though this paper is experimental.

Citations and evidence anchors

  • Journal locator in frontmatter (ACS Appl. Mater. Interfaces 2018, 10, 40831–40837); confirm DOI on the publisher page if needed for linking.