Capture the growth kinetics of CVD growth of two-dimensional MoS2

Abstract

Keywords: molybdenum disulfides, growth mechanism, chemical vapor deposition, transmission electron microscopy Understanding the microscopic mechanism of chemical vapor deposition (CVD) growth of two-dimensional molybdenum disulfide (2D MoS2) is a fundamental issue towards the function-oriented controlled growth. In this work, we report results on revealing the growth kinetics of 2D MoS2 via capturing the nucleation seed, evolution morphology, edge structure and terminations at the atomic scale during CVD growth using the transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) studies. The direct growth of few-and mono-layer MoS2 onto graphene based TEM grids allow us to perform the subsequent TEM characterization without any solution-based transfer. Two forms of seeding centers are observed during 2 characterizations: (i) Mo-oxysulfide (MoOxS2-y) nanoparticles either in multi-shelled fullerene-like structures or in compact nanocrystals for the growth of fewer-layer MoS2;(ii) Mo-S atomic clusters in case of monolayer MoS2. In particular, for the monolayer case, at the early stage growth, the morphology appears in irregular polygon shape comprised with two primary edge terminations: S-Mo Klein edge and Mo zigzag edge, approximately in equal numbers, while as the growth proceeds, the morphology further evolves into near-triangle shape in which Mo zigzag edge predominates. Results from density-functional theory calculations are also consistent with the inferred growth kinetics, and thus supportive to the growth mechanism we proposed. In general, the growth mechanisms found here should also be applicable in other 2D materials, such as MoSe2, WS2 and WSe2 etc.

Doping Nanoscale Graphene Domains Improves Magnetism in Hexagonal Boron Nitride

“…Similarly in single‐layer graphene film, the edge growth along the graphene nucleation on copper substrate leads to the formation of single crystal graphene film by continuously C atoms connecting to the edge of nucleation . This mechanism applies to the growth of 2D single‐layer MoS 2 on substrate . The growth of 2D in‐plane heterostructure also adheres to this mechanism as reported in fabricating the large film of few hundred nanometers graphene domain/h‐BN heterostructures by first having graphene domains on copper substrate and then growing h‐BN domain at the edge of graphene domains .…”

“…Therefore, we infer that the growth of h‐CBN starts to connect B and N atoms to the C atoms along the edge of GQDs and then continues to form h‐BN domains. The edge‐nucleated growth mechanism was reported for CVD synthesis of single crystal h‐BN, graphene, 2D transition metal dichalcogenides, and 2D plane heterostructure . For example, single‐layer h‐BN film follows the process of “nucleation‐growing islands‐forming continuous film”.…”

Strong interlayer hybridization in the aligned SnS2/WSe2 hetero-bilayer structure

“…22 It is noteworthy that the irregular evolution of the SnS 2 edge with respect to WSe 2 edge could be related to the presence of distinct seeding centers, which affect the growth kinetics of the CVD growth of SnS 2 on WSe 2 . 24 To probe the details of light emission obtained from the WSe 2 and SnS 2 /WSe 2 domains, µ-PL spectroscopy was carried out on the microscopic flake of Fig. 1c, using a 532 nm laser excitation.…”

Differentiating Polymorphs in Molybdenum Disulfide via Electron Microscopy

“…Analyzing nanoporous MoS 2 films by STEM, we found that the 1T′ phase can be grown and stabilized at the edges while the basal plane is comprised of the 1H phase. In addition to 1T′ edges, Mo‐Klein edges (Figure e), S‐ZZ edges (Figure f), and Mo‐ZZ (Figure g) edges were also identified …”