Substrate-Induced Variances in Morphological and Structural Properties of MoS₂ Grown by Chemical Vapor Deposition on Epitaxial Graphene and SiO₂

Abstract

In this work, we report the impact of substrate type on the morphological and structural properties of molybdenum disulfide (MoS 2 ) grown by chemical vapor deposition (CVD). MoS 2 synthesized on a three-dimensional (3D) substrate, that is, SiO 2 , in response to the change of the thermodynamic conditions yielded different grain morphologies, including triangles, truncated triangles, and circles. Simultaneously, MoS 2 on graphene is highly immune to the modifications of the growth conditions, forming triangular crystals only. We explain the differences between MoS 2 on SiO 2 and graphene by the different surface diffusion mechanisms, namely, hopping and gas-molecule-collision-like mechanisms, respectively. As a result, we observe the formation of thermodynamically favorable nuclei shapes on graphene, while on SiO 2 , a full spectrum of domain shapes can be achieved. Additionally, graphene withstands the growth process well, with only slight changes in strain and doping. Furthermore, by the application of graphene as a growth substrate, we realize van der Waals epitaxy and achieve strain-free growth, as suggested by the photoluminescence (PL) studies. We indicate that PL, contrary to Raman spectroscopy, enables us to arbitrarily determine the strain levels in MoS 2 .

Carbon Incorporation in MOCVD of MoS2 Thin Films Grown from an Organosulfide Precursor

“…This can be explained by high Mo flux controlled growth rates, 16,17,59 high gas-phase supersaturation at low reactor pressure, 22,35 and low diffusivity of surface species due to hydroxyl anchoring sites on the SiO 2 substrate. 60 While large grain sizes (>μm scale) are typically desired for high-performance (opto)electronic applications, the focus of our investigation was on the origin and effect of C incorporation instead of grain size, as previous works have already addressed the suppression of nucleation density, for example, by alkali-catalyzed synthesis. 38,49 Figure 2c−f shows an exemplary Raman spectrum of the coalesced 1L-MoS 2 film and the three Raman regions of interest.…”

“…The high nucleation density of the first layer (∼10 3 μm –2 ), which has been observed consistently throughout this work (Figure S9), produces a nanocrystalline MoS 2 monolayer with small grain sizes (20–30 nm). This can be explained by high Mo flux controlled growth rates, ,, high gas-phase supersaturation at low reactor pressure, , and low diffusivity of surface species due to hydroxyl anchoring sites on the SiO 2 substrate . While large grain sizes (>μm scale) are typically desired for high-performance (opto)­electronic applications, the focus of our investigation was on the origin and effect of C incorporation instead of grain size, as previous works have already addressed the suppression of nucleation density, for example, by alkali-catalyzed synthesis. , …”

Revealing the Heterogeneity of Large‐Area MoS2Layers in the Electrocatalytic Hydrogen Evolution Reaction

“…[3][4][5][6][7] Single MoS 2 layers show unique properties. They can be synthesised either in a bottom-up, e. g., chemical vapour deposition (CVD), [8][9][10] or top-down, e. g., exfoliation, approach. [11,12] While the latter generally offers high-quality 2D materials, it fails to produce large-scale single layers independ-ently of the substrate and hence lacks scalability.…”

Wafer-scale MoS2 with water-vapor assisted showerhead MOCVD

“…From the broad family of atomically thin, two-dimensional (2D) materials the molybdenum disulphide (MoS 2 ) has been found particularly interesting in recent years. Being a member of the transition metal dichalcogenides (TMD) [1], MoS 2 unique electronic [2,3] and optical properties [4] combined with high mechanical flexibility [5,6] make it an attractive candidate for a potential new generation of wearable devices [7], flexible sensors [8][9][10] or nanoelectronics [2,11] as well as heterostructure research and development [12][13][14][15][16][17][18][19][20]. Therefore, after years of extensive study, the shift of academic focus from small, lab-scale synthesis methods towards the prototype applications and scalable processes is inevitable [21][22][23].…”