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Lateral Versus Vertical Growth of Two-Dimensional Layered Transition-Metal Dichalcogenides: Thermodynamic Insight into MoS2

Summary

The study addresses thermodynamic and diffusion factors governing lateral vs vertical growth of MoS\(_2\) as a prototype 2D TMD. It combines density functional theory (DFT) energetics (including layer-dependent MoS\(_2\), flake-size effects for mono- and bilayers, and migration processes with/without graphene and sapphire substrates) with CALPHAD modeling of Mo–S (and related) phase stability to interpret P–T–x growth windows.

Methods

1 — MD application. N/A — growth mode competition is analyzed with static DFT energetics plus CALPHAD-style P–T–x modeling rather than production AIMD or classical MD in the workflow summarized here.

2 — Force-field training. N/A — not a ReaxFF or classical FF fit study.

3 — Static QM / DFT and thermodynamics. DFT uses PBE-family functionals with documented DFT-D3 dispersion treatments in the SI, plane-wave/PAW-style electronic structure settings, k-point/k-mesh sampling for periodic geometry relaxations of MoS\(_2\), graphene, and sapphire models, and computed energy and barrier quantities along migration pathways that feed CALPHAD construction of Mo–S (and related Mo–S–O–H gas-phase) P–T–x windows. Numerical cutoffs and full property tables are N/A — not duplicated here; use pdf_path and [[2016shang-venue-paper]].

Findings

Thermodynamics and size. Monolayer MoS\(_2\) flakes can be favored at small lateral sizes relative to bilayer islands; a critical lateral size separates mono versus bilayer stability, and that critical size depends on substrate (graphene versus sapphire in the models discussed).

P–T–x interpretation. Size-dependent P–T–x windows are used to locate where smaller flakes preferentially form; the abstract places that window qualitatively in the middle but toward the lower-T, higher-P edge of the gas + MoS\(_2\) region in their diagrams.

Kinetics. Mo migration is argued to be far slower than S, so Mo transport is treated as rate-limiting for growth under the assumptions stated in the paper.

Experiment. The authors report good agreement between their DFT/CALPHAD trends and selected experimental comparisons cited in the article.

Limitations

  • Local corpus metadata lacks a resolved DOI in front matter; confirm bibliographic fields from the PDF header before external citation. Resolve k-meshes, cutoffs, and numerical diagrams from pdf_path and SI [[2016shang-venue-paper]].
  • Growth models depend on DFT approximations and thermodynamic database choices; quantitative windows should be taken from the paper’s figures/tables.

Relevance to group

Penn State materials thermodynamics / 2D synthesis context (Zi-Kui Liu group); not a ReaxFF paper—useful cross-link for 2D TMD processing questions adjacent to reactive MD work.

Citations and evidence anchors

  • Primary PDF: papers/Others/Shang_Liu_MoS2_growth_NanoLetters2016.pdf
  • Text-aligned pointers: normalized/extracts/2016shang-venue-nl-2016-02443v_p1-2.txt