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Highly efficient growth of a centimeter‐scale MoS2 monolayer film by oxide scale sublimation chemical vapor deposition (OSSCVD) in a time as short as 60 s is reported. Benefiting from the superior catalytic ability of Dragontrail glass (DT‐glass) substrate and the controlled large vapor supersaturation of the molybdenum source, the ultrafast deposition of MoS2 is realized with maintaining large‐sized single‐crystalline domains over 20 µm at maximum in the film. It is comparable to those reported for MoS2 grown in tens of minutes and even hours. Similar to the face‐to‐face precursor feed route, the gas‐controlled OSSCVD with a showerhead configuration facilitates a homogeneous and controllable source supply. It enables high‐quality monolayer MoS2 film deposition on 2 × 2 cm2 DT‐glass with centimeter‐scale uniformity confirmed by microscopic, spectroscopic, and electrical characterizations. Back‐gate MoS2 field‐effect transistors fabricated on polycrystalline continuous film exhibit the maximum field‐effect mobility of 5.1 cm2 V−1s−1 and a peak Ion/Ioff ratio of 5 × 108. They reach 40 cm2 V−1 s−1 and 1.2 × 109, respectively, on single‐crystalline domains. These results are even greater than those for MoS2 grown using 1–2 orders of magnitude longer deposition time and higher temperatures. This study highlights the opportunities for low‐cost high‐throughput production of large‐area high‐quality monolayer MoS2. [ABSTRACT FROM AUTHOR]

A newly developed oxide scale sublimation chemical vapor deposition (OSSCVD) technique for 2D MoS2 growth is reported. Gaseous MoO3, which is supplied separately from H2S, can be generated in situ by flowing O2 over Mo metal with oxidation and sublimation processes. In this method, particularly, controllably and abruptly modulating the supply of MoO3 is achievable by precisely tuning O2 flow. Having appropriate conditions, where the generation rate of MoO3 on the Mo metal surface is not larger than its sublimation rate, is critical to enable stable growth. Otherwise, MoS2 deposition can be caused by accumulated MoO3 on the metal surface, regardless of oxygen supply. Proof‐of‐concept experiments with varied process parameters are conducted, confirming OSSCVD enables MoS2 growth with significantly improved flexibility, controllability, and reproducibility relative to conventional powder‐source CVD. By utilizing alkali‐aluminosilicate glass, Dragontrail, as catalytic substrate, single‐crystalline MoS2 triangular domains as large as 25 µm are obtained, followed by a fully covered monolayer on Dragontrail in 25 min. Substrate pretreatment by H2S yields enlarged domain size and reduced domain density, owning to the extracted alkali metals from Dragontrail into the growth zone. The study opens new avenues for the controllable growth of high‐quality MoS2 and other transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) transition metal dichalcogenides (TMDCs) with unique electrical properties are fascinating materials used for future electronics. However, the strong Fermi level pinning effect at the interface of TMDCs and metal electrodes always leads to high contact resistance, which seriously hinders their application in 2D electronics. One effective way to overcome this is to use metallic TMDCs or transferred metal electrodes as van der Waals (vdW) contacts. Alternatively, using highly conductive doped TMDCs will have a profound impact on the contact engineering of 2D electronics. Here, a novel chemical vapor deposition (CVD) using mixed molten salts is established for vapor–liquid–solid growth of high‐quality rhenium (Re) and vanadium (V) doped TMDC monolayers with high controllability and reproducibility. A tunable semiconductor to metal transition is observed in the Re‐ and V‐doped TMDCs. Electrical conductivity increases up to a factor of 108 in the degenerate V‐doped WS2 and WSe2. Using V‐doped WSe2 as vdW contact, the on‐state current and on/off ratio of WSe2‐based field‐effect transistors have been substantially improved (from ≈10–8 to 10–5 A; ≈104 to 108), compared to metal contacts. Future studies on lateral contacts and interconnects using doped TMDCs will pave the way for 2D integrated circuits and flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • A carbon-free inorganic precursor, MoO 2 Cl 2 , as the molybdenum source for atomically thin MoS 2 growth was pioneeringly identified. • Uniquely, MoO 2 Cl 2 is available for integration with the standard well-controlled MOCVD system. • Using MoO 2 Cl 2 and H 2 S as the molybdenum and sulfur sources, respectively, in a standard MOCVD set-up ensures a highly reproducible growth process and eliminates the carbon contamination existing in typical MOCVD-grown MoS 2. • Carbon-free monolayer MoS 2 films were successfully grown with decent quality and wafer-scale homogeneity. To bring atomically thin transition metal dichalcogenides (TMDs) to practical application, a highly reproducible process to grow them over a large scale is indispensable. Here, we develop a carbon-free reproducible route for the scalable growth of high-quality monolayer MoS 2 by selecting molybdenum dichloride dioxide (MoO 2 Cl 2) as the Mo source and integrating the precursor with a standard low-pressure cold-wall metalorganic chemical vapor deposition (MOCVD) system. Specifically, combined with H 2 S as the sulfur source and using catalytic Dragontrail glass (DT-glass) as the main substrate, we investigate the effect of MoO 2 Cl 2 flux, temperature, and deposition time on the growth, confirming MoO 2 Cl 2 with reasonably high vapor pressure is well compatible with the MOCVD system that enables precise control of sources for uniform nucleation and growth of MoS 2 over a large area. We successfully demonstrate the growth of carbon-free MoS 2 monolayers on DT-glass with decent crystalline, optical, and electrical properties. Additionally, the initial attempts also manifest that the proposed strategy could be generalized for growing ultrathin MoS 2 on other technologically important substrates, such as SiO 2 /Si and quartz, exhibiting superior optical quality and wafer-scale uniformity. This work provides a new avenue for the large-scale production of high-quality MoS 2 monolayers and facilitates their use in practical applications. [ABSTRACT FROM AUTHOR]

In order to achieve a uniform distribution of carbon nanotube (CNT) reinforcement in aluminum (Al) matrix, novel nano/micro-sized hybrid reinforcements with CNT growing on the surface of SiC particle (SiCp) was synthesized by a chemical vapor deposition method. Subsequently, the hybrid reinforcement (defined as SiCp(CNT)) was mixed in the pure Al matrix by merely blending powder, as a result, CNT was well-dispersed in the matrix with the help of micro-sized SiCp as a “vehicle”. With the novel reinforcement, SiCp(CNT)/Al composite exhibited both improved elastic modulus of 93 GPa (35% higher than that of Al matrix) and tensile strength of 202 MPa (74% higher than that of Al matrix), mainly because CNT was dispersed uniformly and achieved intimate interfaces with Al matrix with the help of well dispersed SiCp. [ABSTRACT FROM AUTHOR]

Chemical Vapor Deposition: Tunable Doping of Rhenium and Vanadium into Transition Metal Dichalcogenides for Two-Dimensional Electronics (Adv. Sci. 11/2021) A new strategy using mixed salts for chemical vapor deposition of tunable Re- and V-doped 2D transition metal dichalcogenides (TMDCs) is realized by Shisheng Li, Takaaki Taniguchi, and co-workers, as described in article number 2004438. By applying the highly conductive V-doped WSe SB 2 sb as van der Waals contacts for 2D WSe SB 2 sb based field-effect transistor, the on-state current and on/off ratio are substantially improved, compared to the metal contacts. [Extracted from the article]

In this Perspective, we present that polariton modes hosted in two-dimensional (2D) materials can be used to increase and control light–matter interactions at the nanoscale. We analyze the optical response of the most used 2D material nanostructures that support plasmon, exciton, and phonon polariton modes. Polariton characteristic lengths are used to assess the hybrid light–matter modes of different 2D material monolayers and nanoribbons. We present that the 2D material nanodisk can act like a cavity that supports localized polariton modes, which can be excited by a nearby placed quantum system to present ultra-fast and ultra-bright operation. The key to achieve high quality 2D polariton modes is to reduce material losses. Thus, state-of-the-art exfoliation, chemical vapor deposition, and transferring techniques of 2D materials are introduced to fabricate nanostructures that fulfill the stringent requirements of applications in photonics, optoelectronics, and quantum technologies. [ABSTRACT FROM AUTHOR]

Accurate design of the 2D metal–semiconductor (M–S) heterostructure via the covalent combination of appropriate metallic and semiconducting materials is urgently needed for fabricating high‐performance nanodevices and enhancing catalytic performance. Hence, the lateral epitaxial growth of M–S SnxMo1−xS2/MoS2 heterostructure is precisely prepared with in situ growth of metallic SnxMo1−xS2 by doping Sn atoms at semiconductor MoS2 edge via one‐step chemical vapor deposition. The atomically sharp interface of this heterostructure exhibits clearly distinguished performance based on a series of characterizations. The oxygen evolution photoelectrocatalytic performance of the epitaxial M–S heterostructure is 2.5 times higher than that of pure MoS2 in microreactor, attributed to the efficient electron–hole separation and rapid charge transfer. This growth method provides a general strategy for fabricating seamless M–S lateral heterostructures by controllable doping heteroatoms. The M–S heterostructures show increased carrier migration rate and eliminated Fermi level pinning effect, contributing to their potential in devices and catalytic system. [ABSTRACT FROM AUTHOR]