MoS2 synthesis by gas source MBE for transition metal dichalcogenides integration on large scale substrates

Kazzi, Salim El; Mortelmans, Wouter; Nuytten, Thomas; Meersschaut, Johan; Carolan, P.; Landeloos, L.; Conard, Thierry; Radu, Iuliana; Heyns, Marc; Merckling, Clément

doi:10.1063/1.5008933

Cited by 28 publications

(20 citation statements)

References 16 publications

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“…[ 23 ] The virtual WSe 2 (0001) and Bi 2 Se 3 (0001) substrates were fabricated relying on mechanical exfoliation on silicon substrates. [ 33,34 ] The epitaxies were performed using plasma‐assisted (PA‐)MBE with H 2 X radio frequency (RF) plasma sources [ 61 ] and electron‐beam evaporation of elemental W transition metals (Figure 1a) and thermal evaporation of elemental Bi metals (Figure 1b). For the WSe 2 compound, the growths occurred at a temperature of 450 °C with low growth rates of ≈0.1–1.3 ML h −1 , driven by the W evaporation flux.…”

Section: Methodsmentioning

confidence: 99%

Role of Stronger Interlayer van der Waals Coupling in Twin‐Free Molecular Beam Epitaxy of 2D Chalcogenides

Mortelmans

Smet

Meng

et al. 2021

Adv Materials Inter

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Large‐area epitaxy of layered materials is one of the cornerstones for a successful exploitation of van der Waals (vdW) materials in the semiconductor industry. The formation of 60° twin stacking faults and 60° grain boundaries is of major concern for the defect‐free epitaxial growth. Although strategies to overcome the occurrence of these defects are being considered, more fundamental understanding on the origin of these defects is highly essential. This work focuses on understanding the formation of 60° twins in (quasi‐)vdW epitaxy of 2D chalcogenides. Molecular beam epitaxy (MBE) experiments reveal the striking difference in 60° twin occurrence between WSe2 and Bi2Se3 in both quasi‐vdW heteroepitaxy and vdW homoepitaxy. Density functional theory (DFT) calculations link this difference to the interlayer vdW coupling strength at the unit cell level. The stronger interlayer vdW coupling in Bi2Se3 unit cells compared to WSe2 unit cells is explained to result in a reduced twin occurrence. Hence, such compounds show significantly more promise for defect‐free epitaxial integration. This interesting aspect of (quasi‐)vdW epitaxy reveals that the strength of interlayer vdW coupling is key for workable 2D materials and opens perspectives for other strongly coupled vdW materials.

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Section: Methodsmentioning

confidence: 99%

Role of Stronger Interlayer van der Waals Coupling in Twin‐Free Molecular Beam Epitaxy of 2D Chalcogenides

Mortelmans

Smet

Meng

et al. 2021

Adv Materials Inter

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“…While known for producing samples of exceptional quality, MBE is currently incapable of producing truly large-area TMD growths. Modern MBE growths of TMDs such as MoS 2 , MoSe 2 and WSe 2 are restricted to individual flakes with diameters less than a micrometer, a far cry from the ten-centimeter order films produced by other methods [67][68][69]. As a result, MBE is not currently a promising route to large area TMD synthesis.…”

Section: Other Methodsmentioning

confidence: 99%

Large area few-layer TMD film growths and their applications

2020

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Research on 2D materials is one of the core themes of modern condensed matter physics. Prompted by the experimental isolation of graphene, much attention has been given to the unique optical, electronic, and structural properties of these materials. In the past few years, semiconducting transition metal dichalcogenides (TMDs) have attracted increasing interest due to properties such as direct band gaps and intrinsically broken inversion symmetry. Practical utilization of these properties demands large-area synthesis. While films of graphene have been by now synthesized on the order of square meters, analogous achievements are difficult for TMDs given the complexity of their growth kinetics. This article provides an overview of methods used to synthesize films of mono-and few-layer TMDs, comparing spatial and time scales for the different growth strategies. A special emphasis is placed on the unique applications enabled by such large-scale realization, in fields such as electronics and optics.

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“…Atomic layered materials are solids consisting of atomically thin crystals stacked in layers. Modern experimental techniques enable one to produce atomically thin materials of the layers by cleaving from the bulk crystal, chemical vapor deposition, 1,2 , chalcogenation 3 , or molecular-beam epitaxy [4][5][6] . These thin layers have attracted much attention because of the fascinating electronic structures different from those of the bulk crystals.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic spin-valley locking for conducting electrons in metal-semiconductor-metal lateral hetero-structures of $1H$-transition-metal dichalcogenides

Habe

2022

Preprint

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Lateral-hetero structures of atomic layered materials alter the electronic properties of pristine crystals and provide a possibility to produce useful monolayer materials. We reveal that metalsemiconductor-metal lateral-hetero junctions of 1H-transition-metal dichalcogenides intrinsically possess conducting channels of electrons with spin-valley locking, e.g., gate electrode. We theoretically investigate the electronic structure and transport properties of the lateral-hetero junctions and show that the hetero-structure produces conducting channels through the K and K ′ valleys in the semiconducting transition-metal dichalcogenide and restricts the spin of the conducting electrons in each valley due to the valley dependent charge transfer effect. Moreover, the theoretical investigation shows that the hetero-junction of WSe2 realizes a high transmission probability for valley-spin locked electrons even in a long semiconducting region. The hetero-junction also provides a useful electronic transport property, a step-like I-V characteristic.

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MoS2 synthesis by gas source MBE for transition metal dichalcogenides integration on large scale substrates

Cited by 28 publications

References 16 publications

Role of Stronger Interlayer van der Waals Coupling in Twin‐Free Molecular Beam Epitaxy of 2D Chalcogenides

Role of Stronger Interlayer van der Waals Coupling in Twin‐Free Molecular Beam Epitaxy of 2D Chalcogenides

Large area few-layer TMD film growths and their applications

Intrinsic spin-valley locking for conducting electrons in metal-semiconductor-metal lateral hetero-structures of $1H$-transition-metal dichalcogenides

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