Growth of Monolayer and Multilayer MoS<sub>2</sub> Films by Selection of Growth Mode: Two Pathways via Chemisorption and Physisorption of an Inorganic Molecular Precursor

Ahn, Chaehyeon; Park, Younghee; Shin, Sang‐Wan; Ahn, Jong‐Guk; Song, Intek; An, Young Jun; Jung, Jaehoon; Kim, Chung Soo; Kim, Jee Hyeon; Bang, Jiwon; Kim, Dae Hyun; Baik, Jaeyoon; Lim, Hyo Soon

doi:10.1021/acsami.0c19591

Cited by 22 publications

(17 citation statements)

References 44 publications

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“…54 As it is difficult to capture the complex mechanisms in a holistic growth model, Figure 1b illustrates a simplified version of the MOCVD process, involving (1) thermal decomposition In discussion of the growth model, we note that MOCVD reactions occur both in the gas phase and on the surface. Surface reactions involve physisorption and chemisorption processes 55 and substrate-mediated precursor decomposition, such as the decarbonylation of Mo(CO) 6 on SiO 2 . 56 The sulfidation of Mo adatoms results in the nucleation of MoS 2 domains, which grow laterally through edge attachment of additional Mo and S species.…”

Section: Resultsmentioning

confidence: 99%

Carbon Incorporation in MOCVD of MoS₂ Thin Films Grown from an Organosulfide Precursor

et al. 2021

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With the rise of two-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors and their prospective use in commercial (opto)electronic applications, it has become key to develop scalable and reliable TMD synthesis methods with well-monitored and controlled levels of impurities. While metal–organic chemical vapor deposition (MOCVD) has emerged as the method of choice for large-scale TMD fabrication, carbon (C) incorporation arising during MOCVD growth of TMDs has been a persistent concernespecially in instances where organic chalcogen precursors are desired as a less hazardous alternative to more toxic chalcogen hydrides. However, the underlying mechanisms of such unintentional C incorporation and the effects on film growth and properties are still elusive. Here, we report on the role of C-containing side products of organosulfur precursor pyrolysis in MoS2 thin films grown from molybdenum hexacarbonyl Mo(CO)6 and diethyl sulfide (CH3CH2)2S (DES). By combining in situ gas-phase monitoring with ex situ microscopy and spectroscopy analyses, we systematically investigate the effect of temperature and Mo(CO)6/DES/H2 gas mixture ratios on film morphology, chemical composition, and stoichiometry. Aiming at high-quality TMD growth that typically requires elevated growth temperatures and high DES/Mo(CO)6 precursor ratios, we observed that temperatures above DES pyrolysis onset (≳600 °C) and excessive DES flow result in the formation of nanographitic carbon, competing with MoS2 growth. We found that by introducing H2 gas to the process, DES pyrolysis is significantly hindered, which reduces carbon incorporation. The C content in the MoS2 films is shown to quench the MoS2 photoluminescence and influence the trion-to-exciton ratio via charge transfer. This finding is fundamental for understanding process-induced C impurity doping in MOCVD-grown 2D semiconductors and might have important implications for the functionality and performance of (opto)electronic devices.

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Section: Resultsmentioning

confidence: 99%

Carbon Incorporation in MOCVD of MoS₂ Thin Films Grown from an Organosulfide Precursor

et al. 2021

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“…Very recently, Ahn et al. developed an experimental method to grow layer-controlled MoS 2 films using MoOCl 4 -based chemistry, with control achieved by simply varying the pressure in the system (Ahn et al, 2021) . Future work can explore such ideas from a computational perspective to discover growth strategies to enable layer control for 2D materials.…”

Section: Knowledge Gaps and Future Research Directionsmentioning

confidence: 99%

Chemical vapor deposition of 2D materials: A review of modeling, simulation, and machine learning studies

Bhowmik¹,

Rajan²

2022

iScience

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“…To achieve the large-area growth of monolayer MoS 2 , various methods have been reported, including confined-space CVD, reverse-flow chemical vapor epitaxy, inorganic vapor CVD, and metal organic CVD, etc. [ 38 , 39 , 40 , 41 , 42 , 43 , 44 ].…”

Section: Introductionmentioning

confidence: 99%

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

Bae

Yoo

2021

Nanomaterials

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Monolayer MoS2 can be used for various applications such as flexible optoelectronics and electronics due to its exceptional optical and electronic properties. For these applications, large-area synthesis of high-quality monolayer MoS2 is highly desirable. However, the conventional chemical vapor deposition (CVD) method using MoO3 and S powder has shown limitations in synthesizing high-quality monolayer MoS2 over a large area on a substrate. In this study, we present a novel carbon cloth-assisted CVD method for large-area uniform synthesis of high-quality monolayer MoS2. While the conventional CVD method produces thick MoS2 films in the center of the substrate and forms MoS2 monolayers at the edge of the thick MoS2 films, our carbon cloth-assisted CVD method uniformly grows high-quality monolayer MoS2 in the center of the substrate. The as-synthesized monolayer MoS2 was characterized in detail by Raman/photoluminescence spectroscopy, atomic force microscopy, and transmission electron microscopy. We reveal the growth process of monolayer MoS2 initiated from MoS2 seeds by synthesizing monolayer MoS2 with varying reaction times. In addition, we show that the CVD method employing carbon powder also produces uniform monolayer MoS2 without forming thick MoS2 films in the center of the substrate. This confirms that the large-area growth of monolayer MoS2 using the carbon cloth-assisted CVD method is mainly due to reducing properties of the carbon material, rather than the effect of covering the carbon cloth. Furthermore, we demonstrate that our carbon cloth-assisted CVD method is generally applicable to large-area uniform synthesis of other monolayer transition metal dichalcogenides, including monolayer WS2.

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Growth of Monolayer and Multilayer MoS₂ Films by Selection of Growth Mode: Two Pathways via Chemisorption and Physisorption of an Inorganic Molecular Precursor

Cited by 22 publications

References 44 publications

Carbon Incorporation in MOCVD of MoS₂ Thin Films Grown from an Organosulfide Precursor

Carbon Incorporation in MOCVD of MoS₂ Thin Films Grown from an Organosulfide Precursor

Chemical vapor deposition of 2D materials: A review of modeling, simulation, and machine learning studies

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

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Growth of Monolayer and Multilayer MoS2 Films by Selection of Growth Mode: Two Pathways via Chemisorption and Physisorption of an Inorganic Molecular Precursor

Cited by 22 publications

References 44 publications

Carbon Incorporation in MOCVD of MoS2 Thin Films Grown from an Organosulfide Precursor

Carbon Incorporation in MOCVD of MoS2 Thin Films Grown from an Organosulfide Precursor

Chemical vapor deposition of 2D materials: A review of modeling, simulation, and machine learning studies

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

Contact Info

Product

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Growth of Monolayer and Multilayer MoS₂ Films by Selection of Growth Mode: Two Pathways via Chemisorption and Physisorption of an Inorganic Molecular Precursor

Carbon Incorporation in MOCVD of MoS₂ Thin Films Grown from an Organosulfide Precursor

Carbon Incorporation in MOCVD of MoS₂ Thin Films Grown from an Organosulfide Precursor