Uniform large-area growth of nanotemplated high-quality monolayer MoS2

Abstract

Over the past decade, it has become apparent that the extreme sensitivity of 2D crystals to surface interactions presents a unique opportunity to tune material properties through surface functionalization and the mechanical assembly of 2D heterostructures. However, this opportunity carries with it a concurrent challenge: an enhanced sensitivity to surface contamination introduced by standard patterning techniques that is exacerbated by the difficulty in cleaning these atomically thin materials. Here, we report a templated MoS2 growth technique wherein Mo is deposited onto atomically stepped sapphire substrates through a SiN stencil with feature sizes down to 100 nm and subsequently sulfurized at high temperature. These films have a quality comparable to the best MoS2 prepared by other methodologies, and the thickness of the resulting MoS2 patterns can be tuned layer-by-layer by controlling the initial Mo deposition. The quality and thickness of the films are confirmed by scanning electron, scanning tunneling, and atomic force microscopies; Raman, photoluminescence, and x-ray photoelectron spectroscopies; and electron transport measurements. This approach critically enables the creation of patterned, single-layer MoS2 films with pristine surfaces suitable for subsequent modification via functionalization and mechanical stacking. Further, we anticipate that this growth technique should be broadly applicable within the family of transition metal dichalcogenides.

Highly Sensitive NO2 Detection by TVS-Grown Multilayer MoS2 Films

“…Since the FWHM of the E 2g 1 mode is known to be relatively insensitive to the number of layers, it could be used as an index for comparing the crystalline quality. The FWHM values of E 2g 1 and A 1g of our film are found to be 3.0 and 3.2, respectively (Figure S3), which are narrower than previously reported values taken from TVS-grown films. − Furthermore, single-layer MoS 2 films grown by CVD have exhibited the values in the range of 3.2–3.8 for E 2g 1 and 3.7–6.8 cm –1 for A 1g , − suggesting that the crystalline quality of our TVS-grown film is comparable to that of the CVD-grown films in the previous reports. The chemical composition of the MoS 2 film was characterized by XPS (see Figure S4).…”

Synthesis and characterization of WS2/graphene/SiC van der Waals heterostructures via WO3−x thin film sulfurization

“…We envisage that the thin-film sulfurization approach can similarly provide a versatile method of synthesizing a broad range of TMDs, heterostructures or alloys based on the choice of precursors 30 . This approach may also lend itself to TMD nanostructure fabrication by pre-patterning the metal oxide precursor prior to sulfurization 60 .…”

Single variable defined technology control of the optical properties in MoS2 films with controlled number of 2D-layers

“…Recently it was demonstrated that the crystallinity in the MoS 2 layers is dependent on the deposition temperature and thickness of the metallic Mo film [14]. These technological variables were also found acceptable to tune the properties layer by layer in the stacked MoS 2 structures [15]. However, there are still no clear guiding principles acceptable to relate the technological conditions and the resulting properties of the 2D TMDs based structures.…”