High-Mobility and High-Optical Quality Atomically Thin WS 2

Abstract

The rise of atomically thin materials has the potential to enable a paradigm shift in modern technologies by introducing multi-functional materials in the semiconductor industry. To date the growth of high quality atomically thin semiconductors (e.g. WS2) is one of the most pressing challenges to unleash the potential of these materials and the growth of mono- or bi-layers with high crystal quality is yet to see its full realization. Here, we show that the novel use of molecular precursors in the controlled synthesis of mono- and bi-layer WS2 leads to superior material quality compared to the widely used direct sulfidization of WO3-based precursors. Record high room temperature charge carrier mobility up to 52 cm2/Vs and ultra-sharp photoluminescence linewidth of just 36 meV over submillimeter areas demonstrate that the quality of this material supersedes also that of naturally occurring materials. By exploiting surface diffusion kinetics of W and S species adsorbed onto a substrate, a deterministic layer thickness control has also been achieved promoting the design of scalable synthesis routes.

Facile and Controllable Synthesis of Large-Area Monolayer WS2 Flakes Based on WO3 Precursor Drop-Casted Substrates by Chemical Vapor Deposition

“…To probe the light emission and further determine the layer number of the triangular WS 2 flake, the room temperature PL spectrum was collected with a 532 nm laser excitation. As shown in Figure 3b, a single and strong peak with a maxima wavelength of 632 nm (~1.96 eV) is observed, which is consistent with the reported PL peak position for monolayer WS 2 [41,54,55], again confirming the monolayer nature of the as-grown WS 2 .…”

Engineered 2D Transition Metal Dichalcogenides—A Vision of Viable Hydrogen Evolution Reaction Catalysis

“…[ 26 ] The earliest reports of TMDs for electrochemical water‐splitting come from the late 1970s. [ 27 ] The explosion of interest in TMD materials corresponds to the development of exfoliation [ 28 ] and synthesis [ 29,30 ] techniques that have enabled the production and stabilization of monolayers. These monolayers enable a higher per mass catalytically active surface area, and thus more catalytically active basal‐plane, defect, and edge sites available for the HER to occur.…”

Spin-orbit interaction induced in graphene by transition metal dichalcogenides

“…Monolayer graphene is identified by means of optical contrast under the microscope, and by quantum Hall effect measurements. For TMDs, the fabrication process is different for different materials: Monolayer WS 2 and MoS 2 are prepared by the CVD method 47,51,52,64 , and the other TMDs are prepared by mechanical exfoliation of bulk cristals on SiO 2 /doped-Si substrates. For graphene/monolayer TMD samples, graphene is transferred on a monolayer TMD by using polymethyl methacrylate (PMMA) or mechanically exfoliated hexagonal boron-nitride (hBN) using polydimethylsiloxane (PDMS).…”