NaCl-assisted substrate dependent 2D planar nucleated growth of MoS2

Sharma

Crystal Growth & Design

2021

Self Cite

Direct growth of wafer scale high quality 2D layered materials (2DLMs) on SiO2/Si substrate is still a challenge. The chemical vapor deposition (CVD) technique has played a significant role in achieving a large area continuous film of 2DLMs. CVD growth requires the optimization of many growth parameters such as temperature, amount of precursors, pressure, carrier gas flow and distance between the reactants. However, the role of boundary layer of reactants concentration has not been explored yet. The amount of precursors which leads to the formation of reactants concentration boundary layer has a significant role in controlling the thickness of growing material. Here, we report the role of concentration boundary layer to achieve wafer-scale MoS2 in NaCl-assisted CVD growth at low temperature. Control of boundary layer thickness has led to the synthesis monolayer, bilayer, trilayer, and bulk MoS2 film and flakes in our single-zone CVD at atmospheric pressure. Most importantly, we have synthesized 7 × 2.5 cm 2 area continuous, high quality trilayer MoS2 film with good repeatability. We believe that our approach may lead to synthesize other wafer-scale 2DLMs that will pave the way for nano-and optoelectronics.2

Section: Results and Discussionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

NaCl-Assisted CVD Growth of Large-Area High-Quality Trilayer MoS₂ and the Role of the Concentration Boundary Layer

Sharma

Crystal Growth & Design

2021

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“… 40 , 41 As shown in Figure 4 e,f, it has been observed that all the peak positions and FWHMs of the transferred film are almost similar to those of the as-grown film, indicating no change in the stoichiometry and chemical composition of the 3L MoS 2 film after the transfer. The presence of Na 2 S/Na 2 SO 4 underneath the MoS 2 film was confirmed by Na 1s core-level spectra of the as-grown film positioned at 1071.2 eV 42 , 43 ( Figure 4 g). However, no Na 1s peak was observed in the transferred 3L MoS 2 , confirming the dissolution of the Na 2 S/Na 2 SO 4 layer during the transfer process ( Figure 4 h).…”

Section: Resultsmentioning

confidence: 78%

“…As reported in our previous work, a water-soluble layer (Na 2 S/Na 2 SO 4 ) was also grown underneath MoS 2. 42 , 64 The Na 2 S/Na 2 SO 4 layer functions as a seed promoter and supports the nucleation of the large-area, uniform, and continuous MoS 2 film.…”

Section: Experimental Sectionmentioning

confidence: 99%

Large-Area Transfer of 2D TMDCs Assisted by a Water-Soluble Layer for Potential Device Applications

et al. 2022

Self Cite

Layer transfer offers enormous potential for the industrial implementation of two-dimensional (2D) material technology platforms. However, the transfer method used must retain the as-grown uniformity and cleanliness in the transferred films for the fabrication of 2D material-based devices. Additionally, the method used must be capable of large-area transfer to maintain wafer-scale fabrication standards. Here, a facile route to transfer centimeter-scale synthesized 2D transition metal dichalcogenides (TMDCs) (3L MoS 2 , 1L WS 2 ) onto various substrates such as sapphire, SiO 2 /Si, and flexible substrates (mica, polyimide) has been developed using a water-soluble layer (Na 2 S/Na 2 SO 4 ) underneath the as-grown film. The developed transfer process represents a fast, clean, generic, and scalable technique to transfer 2D atomic layers. The key strategy used in this process includes the dissolution of the Na 2 S/Na 2 SO 4 layer due to the penetration of NaOH solution between the growth substrate and hydrophobic 2D TMDC film. As a proof-of-concept device, a broadband photodetector has been fabricated onto the transferred 3L MoS 2 , which shows photoresponse behavior for a wide range of wavelengths ranging from near-infrared (NIR) to UV. The enhancement in photocurrent was found to be 100 times and 10 times the dark current in the UV and visible regions, respectively. The fabricated photodetector shows a higher responsivity of 8.6 mA/W even at a low applied voltage (1.5 V) and low power density (0.6 μW/mm 2 ). The detector enables a high detectivity of 2.9 × 10 11 Jones. This work opens up the pathway toward flexible electronics and optoelectronics.

mentioning

confidence: 99%

Additive‐Assisted Growth of Scaled and Quality 2D Materials

Qing

Xiao

Lin

et al. 2022

Small

have a lattice structure that is quite similar to that of graphene, and it has important applications in heat conduction, lubrication, hydrogen storage, battery diaphragm materials, high temperature anti-oxidation coatings, catalysis and other fields. [6] Transition metal dichalcogenides (TMDs) materials, as compared to graphene, break through the application bottleneck of zero band gap and have shown to be useful on electrical devices. [7] The ability to convert indirect bandgaps into direct bandgaps increases their applicability in optoelectronic devices even further. [8] Moreover, TMDs also have enticing qualities in the fields of magnetism and catalysis. [9][10][11] Without the controllable preparation of their solid thin films, these various applications will not be accomplished. Chemical vapor deposition (CVD) has proven to be a versatile platform for generating solid several-atom-thick films of 2D materials and is being pushed to adapt more and more manufacturing requirements via chemical reactions on a heated substrate among those as-developed techniques. Figure 1 graphically depicts the CVD growth mechanisms of graphene, h-BN and TMDs. Researchers have optimized the CVD development from a variety of perspectives over the last few decades, including improving product and pollution removal, making it more and more suitable for modern industry. [12,13] Moreover, significant progress has been made in wafer-scale preparations, [12,14] heterojunctions, [15][16][17][18] superlattices, [19,20] super-clean products, [21][22][23] and the use of liquid metal substrates, [24,25] However, other concerns still need to be solved, for example, such as the high reaction temperature, low growth rate, smallarea domains, and poor repeatability between labs. As a result, researchers have experimented with various additives to tackle these issues. By regulating kinetics, tuning sublimation temperature, minimizing flaws, and so on, this is a relatively low-cost method of improving the growth environment of 2D materials. Recent scientific research development has been satisfying. The introduction of additives has demonstrated outstanding results in terms of lowering reaction temperature, increasing reaction speed, ensuring smooth growth, and lowering nucleation density.The most recent advancements in the field of additivesassisted CVD production of 2D materials have been carefully described in this review. The additives are separated into categories based on the materials to be used and their natural forms, which mostly include vapors and solids. This section focuses on modified CVD equipments, influence factors, and product 2D materials are increasingly becoming key components in modern electronics because of their prominent electronic and optoelectronic properties. The central and premise to the entire discipline of 2D materials lie in the high-quality and scaled preparations. The chemical vapor deposition (CVD) method offers compelling benefits in terms of scalability and controllability in shaping largearea and high-quality...