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

• DOI: 10.1021/acs.nanolett.6b02443
• Publication Date: 2016-08-19T16:27:18Z
• Authors: Shun-Li Shang; Greta Lindwall; Yi Wang; Joan M. Redwing; Tim Anderson; Zi-Kui Liu
• Keywords: 01 natural sciences; 0104 chemical sciences

Unprecedented interest has been spurred recently in two-dimensional (2D) layered transition metal dichalcogenides (TMDs) that possess tunable electronic and optical properties. However, synthesis of a wafer-scale TMD thin film with controlled layers homogeneity remains highly challenging due mainly to the lack thermodynamic diffusion knowledge, which can be used understand design process conditions, but falls far behind rapidly growing field. Here, an integrated density functional theory (DFT) calculation phase diagram (CALPHAD) modeling approach is employed provide insight into lateral versus vertical growth prototypical 2D material MoS2. Various DFT energies are predicted from layer-dependent MoS2, flake-size related mono- bilayer Mo S migrations without graphene sapphire substrates, thus shedding light on factors control islands. For example, monolayer MoS2 flake small size thermodynamically favorable respect counterpart, indicating preference during initial stage nucleation; while becomes stable increasing size. The critical stability between adjustable via choice substrate. In terms CALPHAD modeling, dependent pressure–temperature–composition (P-T-x) windows for formation reduced appears middle close lower T higher P "Gas + MoS2" region. It further suggests controlling factor owing its extremely low diffusivity compared sulfur. Calculated energies, diffusivities, size-dependent P-T-x good accord available experiments, present data quantitative