Epitaxial Growth of Single‐Phase 1T'‐WSe<sub>2</sub> Monolayer with Assistance of Enhanced Interface Interaction

Chen, Wang; Hu, Mengli; Zong, Junyu; Xie, Xuedong; Meng, Qinghao; Yu, Fan; Wang, Li; Ren, Wei; Chen, Ai-Xi; Liu, Gan; Xi, Xiaoxiang; Li, Fangsen; Sun, Junqiang; Liu, Junwei; Zhang, Yi

doi:10.1002/adma.202004930

Cited by 34 publications

(38 citation statements)

References 52 publications

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“…The epitaxial 1T′-MoTe 2 films usually contain a majority of 2H-MoTe 2 domains because of the near degenerate energies of 1T′ and 2H phases of MoTe 2 . [42,43,60] Previous studies have indicated that, the strain control [25,49,51] and external electrical fields [50] were beneficial for the formation of 1T′-MoTe 2 .…”

Section: Phase Structure Of 1t′-mote 2 /Bi 2 Te 3 Vdwhmentioning

confidence: 99%

“…[11,22,[41][42][43] Thus, of equal importance is their synthesis that always requires supporting substrates to stabilize the 1T′ structure. [25,44,45] As the sake of the fabrication of QSH-based devices, it is highly desirable to realize stable 1T′-MX 2 MLs with positive global band gaps by binding with suitable substrates and utilizing the proximity effects in their heterostructures.…”

Section: Introductionmentioning

confidence: 99%

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Tendency of Gap Opening in Semimetal 1T′‐MoTe₂ with Proximity to a 3D Topological Insulator

Zhang

Wei

Zhan

et al. 2021

Adv Funct Materials

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Monolayer (ML) 1T′-MoTe 2 has attracted intensive interest as a fascinating quantum spin Hall (QSH) insulator. However, there are two critical aspects impeding its exploration and potential applications of QSH effects. One is its semimetallic feature with a negative band gap, leading to nontrivial edge channels annihilated by the bulk states. The other is its fabrication always accompanied by a mixed phase of 1T′ and 2H. Based on first-principles calculations, it is shown that the large work-function difference results in strong interlayer interactions and proximity effects in ML 1T′-MoTe 2 via interfacing a 3D topological insulator Bi 2 Te 3 , facilitating the realization of pure 1T′ phase and even the band gap opening. It is further verified that the epi-grown ML 1T′-MoTe 2 on Bi 2 Te 3 is nearly in single phase. Furthermore, the measurements of angle resolved photoemission spectroscopy and scanning tunneling spectroscopy confirm the obvious separated-tendency of conduction and valence bands as well as the strong metallic edge states in ML 1T′-MoTe 2 . The results also reveal the nontrivial band topology in ML 1T′-MoTe 2 is preserved in 1T′-MoTe 2 /Bi 2 Te 3 heterostructure. This work offers a promising candidate to realize QSH effects and provides guidance for controlling the nontrivial band gap opening by proximity effects in van der Waals engineering.

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Section: Phase Structure Of 1t′-mote 2 /Bi 2 Te 3 Vdwhmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tendency of Gap Opening in Semimetal 1T′‐MoTe₂ with Proximity to a 3D Topological Insulator

Zhang

Wei

Zhan

et al. 2021

Adv Funct Materials

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“…Strain is one of the most important approaches to tune the electronic properties of 2D materials. Experimental results prove the strain can induce metal-insulator transition and enhance the metastable phase growth [29,43]. In this section, we introduce the strained TB model based on the I-TB model.…”

Section: Strained Tb Modelmentioning

confidence: 99%

“…* liuj@ust.hk In addition to the extensive studies of WTe 2 , the exploration has also been extended to other related materials. For example, monolayer 1T'-WSe 2 [27][28][29] , 1T'-MoSe 2 [30], 1T'-MoTe 2 [31] and 1T'-MoS 2 [32] are successfully fabricated; plus WSe 2 and MoS 2 show a gapped bulk and conducting edge states in experiments. Observations of topological Fermi arcs [33] and superconductivity [34] in bulk MoTe 2 are also reported.…”

Section: Introductionmentioning

confidence: 99%

Realistic tight-binding model for monolayer transition metal dichalcogenides in 1T' structure

Hu,

Ma,

Wan

et al. 2021

Preprint

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Monolayer transition metal dichalcogenides M X2 (M = Mo,W and X = Te, Se, S) in 1T' structure were predicted to be quantum spin Hall insulators based on first-principles calculations, which were quickly confirmed by multiple experimental groups. For a better understanding of their properties, in particular their responses to external fields, we construct a realistic four-band tight-binding (TB) model by combining the symmetry analysis and first-principles calculations. Our TB model respects all the symmetries and can accurately reproduce the band structure in a large energy window from -0.3 eV to 0.8 eV. With the inclusion of spin-orbital coupling (SOC), our TB model can characterize the nontrivial topology and the corresponding edge states. Our TB model can also capture the anisotropic strain effects on the band structure and the strain-induced metal-insulator transition. Moreover, we found that although M X2 share the same crystal structures and have the same crystal symmetries, while the orbital composition of states around the Fermi level are qualitatively different and their lower-energy properties cannot fully described by a single k • p model. Thus, we construct two different types of k • p model for M S2,M Se2 and M Te2, respectively. Benefiting from the high accuracy and simplicity, our TB and k • p models can serve as a solid and concrete starting point for future studies of transport, superconductivity, strong correlation effects and twistronics in 1T'-transition metal dichalcogenides.

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“…Indeed, the 2D materials over the oxide surface facilitate direct device fabrication 35,36 . However, the fabrication process of monolayer WSe 2 film is yet sophisticated compared with other TMDCs 37 …”

Section: Introductionmentioning

confidence: 99%

High‐performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre‐seeding strategy

Zhang

Pang

Cheng

et al. 2021

InfoMat

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Tungsten diselenide (WSe2) possesses extraordinary electronic properties for applications in electronics, optoelectronics, and emerging exciton physics. The synthesis of monolayer WSe2 film is of topmost for device arrays and integrated circuits. The monolayer WSe2 film has yet been reported by thermal chemical vapor deposition (CVD) approach, and the nucleation mechanism remains unclear. Here, we report a pre‐seeding strategy for finely regulating the nuclei density at an early stage and achieving a fully covered film after chemical vapor deposition growth. The underlying mechanism is heterogeneous nucleation from the pre‐seeding tungsten oxide nanoparticles. At first, we optimized the precursor concentration for pre‐seeding. Besides, we confirmed the superiority of the pre‐seeding method, compared with three types of substrate pretreatments, including nontreatment, sonication in an organic solvent, and oxygen plasma. Eventually, the high‐quality synthetic WSe2 monolayer film exhibits excellent device performance in field‐effect transistors and photodetectors. We extracted thermodynamic activation energy from the nucleation and growth data. Our results may shed light on the wafer‐scale production of homogeneous monolayer films of WSe2, other 2D materials, and their van der Waals heterostructures.

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Epitaxial Growth of Single‐Phase 1T'‐WSe₂ Monolayer with Assistance of Enhanced Interface Interaction

Cited by 34 publications

References 52 publications

Tendency of Gap Opening in Semimetal 1T′‐MoTe₂ with Proximity to a 3D Topological Insulator

Tendency of Gap Opening in Semimetal 1T′‐MoTe₂ with Proximity to a 3D Topological Insulator

Realistic tight-binding model for monolayer transition metal dichalcogenides in 1T' structure

High‐performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre‐seeding strategy

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Epitaxial Growth of Single‐Phase 1T'‐WSe2 Monolayer with Assistance of Enhanced Interface Interaction

Cited by 34 publications

References 52 publications

Tendency of Gap Opening in Semimetal 1T′‐MoTe2 with Proximity to a 3D Topological Insulator

Tendency of Gap Opening in Semimetal 1T′‐MoTe2 with Proximity to a 3D Topological Insulator

Realistic tight-binding model for monolayer transition metal dichalcogenides in 1T' structure

High‐performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre‐seeding strategy

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Product

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Epitaxial Growth of Single‐Phase 1T'‐WSe₂ Monolayer with Assistance of Enhanced Interface Interaction

Tendency of Gap Opening in Semimetal 1T′‐MoTe₂ with Proximity to a 3D Topological Insulator

Tendency of Gap Opening in Semimetal 1T′‐MoTe₂ with Proximity to a 3D Topological Insulator