Two-Step Growth of Uniform Monolayer MoS₂ Nanosheets by Metal–Organic Chemical Vapor Deposition

Abstract

To achieve large area growth of transition metal dichalcogenides of uniform monolayer thickness, we demonstrate metal–organic chemical vapor deposition (MOCVD) growth under low pressure followed by a high-temperature sulfurization process under atmospheric pressure (AP). Following sulfurization, the MOCVD-grown continuous MoS 2 film transforms into compact triangular crystals of uniform monolayer thickness as confirmed from the sharp distinct photoluminescence peak at 1.8 eV. Raman and X-ray photoelectron spectroscopies confirm that the structural disorders and chalcogen vacancies inherent to the as-grown MOCVD film are substantially healed and carbon/oxygen contaminations are heavily suppressed. The as-grown MOCVD film has a Mo/S ratio of 1:1.6 and an average defect length of ∼1.56 nm, which improve to 1:1.97 and ∼21 nm, respectively, upon sulfurization. The effect of temperature and duration of the sulfurization process on the morphology and stoichiometry of the grown film is investigated in detail. Compared to the APCVD growth, this two-step growth process shows more homogenous distribution of the triangular monolayer MoS 2 domains across the entire substrate, while demonstrating comparable electrical performance.

A Novel Carbon-Assisted Chemical Vapor Deposition Growth of Large-Area Uniform Monolayer MoS2 and WS2

“…Additional data on the optical characterization of the MoS 2 grown using the conventional CVD method are shown in Supplementary Materials Figure S1 . The growth of such thick MoS 2 films and partial formation of monolayer MoS 2 have been commonly observed in MoS 2 growth by the conventional CVD method using MoO 3 and S powder as precursors [ 30 , 31 , 32 , 33 , 34 ]. An AFM height image of monolayer MoS 2 shows small particles grown nonuniformly on the surface of monolayer MoS 2 ( Figure 1 g).…”

“…In contrast, the chemical vapor deposition (CVD) method can control the number of MoS 2 layers and enables wafer-scale synthesis [ 27 , 28 , 29 ]. However, the conventional CVD method using MoO 3 and S powder has a problem in that thick MoS 2 films are formed in the center of the substrate and only MoS 2 monolayers are generated at the edge of the thick MoS 2 films [ 30 , 31 , 32 , 33 , 34 ].…”

Scalably Nanomanufactured Atomically Thin Materials‐Based Wearable Health Sensors

“…[ 321,375,376 ] Researchers observed that the addition of selected synergistic additives, such as a small amount of O 2 , N 2 , or H 2 O vapor, [ 185,377 ] or the seed promoter (e.g., aromatic molecules), [ 378–380 ] to the CVD process, can result in large‐area, uniform, crystalline monolayer materials with exceptional optical and electrical properties. [ 198,381,382 ] For example, Asif et al [ 377 ] used water‐assisted CVD for synthesizing multilayer graphene. With increased water vapor concentration from 0 to 2000 ppmv, graphene layers increase from 2 to 25 layers.…”

Intermediate Cu-O-Si Phase in the Cu-SiO2/Si(111) System: Growth, Elemental, and Electrical Studies

“…However, this method of referencing that corresponds to adventitious carbon contaminations might be erroneous as the elemental composition and thickness of the film vary. 60 The chemical composition of the grown film was quantified using the Casa XPS software. In the deconvolution process, some of the peak parameters like binding energy, FWHM, peak area, etc., were kept fixed 61 and the fitting of the spectra were performed using either a combination of the Gaussian/Lorentzian function with GL line shapes (with varying FWHM for component peaks) or with the Voigt function following a Shirley background correction.…”