Dual-coupling-guided epitaxial growth of wafer-scale single-crystal WS2 monolayer on vicinal a-plane sapphire

Wang, Jinhuan; Xu, Xiaozhi; Cheng, Ting; Gu, Lehua; Qiao, Ruixi; Liang, Zhihua; Ding, Dongdong; Hong, Hao; Zheng, Peiming; Zhang, Zhibin; Zhang, Shuai; Cui, Guoliang; Chang, Chao; Huang, Chen; Qi, Jiajie; Liang, Jing; Liu, Can; Zuo, Yonggang; Xue, Guodong; Fang, Xinjie; Tian, Jinpeng; Wu, Muhong; Guo, Yi; Yao, Zhixin; Jiao, Qingze; Liu, Lei; Gao, Peng; Li, Qunyang; Yang, Rong; Zhang, Guangyu; Tang, Zhilie; Yu, Dapeng; Wang, Enge; Lü, Jianming; Zhao, Yun; Wu, Shiwei; Ding, Feng; Liu, Kaihui

doi:10.1038/s41565-021-01004-0

Cited by 187 publications

(210 citation statements)

References 39 publications

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“…It was reported that the steps on epitaxial substrate have been successfully employed to grow wafer-scale 2D materials with threefold symmetry on epitaxial substrate with higher symmetry, including the monolayer h-BN on copper and monolayer MoS 2 on sapphire. [2,4,26,42] The underlying mechanism is attributed to that the presence of surface step can break the energetically degenerated but antiparallel epitaxy directions of 2D materials and lead to the unidirectional nucleation and growth. [26] Zhou et al also realized multilayer WSe 2 on stepped sapphire surface through a layer-over-layer route, where the WSe 2 layers nucleated from upstream steps grow on top of WSe 2 layer nucleated at downstream steps.…”

Section: (mentioning

confidence: 99%

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS₂ with Controllable Thickness

et al. 2022

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consequently low carrier density limit its performance in electronic devices. [10] The carrier mobility of monolayer MoS 2 is relatively low and can even be seriously vulnerable against the optical phonons, defect and impurities. [11][12][13] Multilayer MoS 2 exposes much higher current density (400-1500 µA µm −1 ) and mobility (200-500 cm 2 V −1 s −1 ) than monolayer MoS 2 (current density: 50-700 µA µm −1 ; mobility: 70-100 cm 2 V −1 s −1 ), [14][15][16][17] making them more suitable for electronic application such as field effect transistors (FETs) and 2D device integrated circuits. Quantum transport simulations suggested that the bilayer and trilayer MoS 2 -based FETs could show better performance than the monolayer MoS 2 . [18][19][20] Excitingly, the bilayer MoS 2 based devices have been successfully demonstrated with very promising performance in experimental works. [21,22] Liu et al. produced bilayer MoS 2 films by the Scotch-tape technique and fabricated FETs devices with high on/ off ratio of 1 × 10 8 and field effect mobility of 517 cm 2 V −1 s −1 . [23] In addition, it was shown that the layerdependent electronic structures of multilayer MoS 2 can give rise to the unique optoelectronic response in devices. [24] However, the growth of large-area uniform multilayer MoS 2 , as the prerequisite of industrial application, is still very challenging. [25] Actually, the grand breakthrough was not made until very recently in the wafer-scale growth of monolayer MoS 2 single crystal films, in comparison with which the growth of large-area uniform multilayer MoS 2 is severely lagged. [26] Presently, the growth of multilayer MoS 2 films has commonly been achieved through the layer-by-layer growth mode via chemical vapor deposition (CVD) methods. [16,27,28] However, the multilayer MoS 2 films prepared by this route show poor uniformity on the thickness and domain size. This is attributed to that the nucleation of top-layer has to be occurred on the surface of previously grown bottom MoS 2 films, making it difficult to control the thickness and domain size of grown MoS 2 domain. Besides, the layer-by-layer growth mode would suffer from the synthesis time penalty and insufficient growth time will lead to a much smaller area of the upper MoS 2 layer than that of the lower layer and consequently a much smaller usable area of the grown film. [13] Hong et al. claimed that the growth of wafer-scale MoS 2 polycrystalline films within five layers could Multilayer MoS 2 shows superior performance over the monolayer MoS 2 for electronic devices while the growth of multilayer MoS 2 with controllable and uniform thickness is still very challenging. It is revealed by calculations that monolayer MoS 2 domains are thermodynamically much more favorable than multilayer ones on epitaxial substrates due to the competition between surface interactions and edge formation, leading accordingly to a layer-bylayer growth pattern and non-continuously distributed multilayer domains with uncontrollable thickness uniformity. The thermodynamics ...

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Section: (mentioning

confidence: 99%

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS₂ with Controllable Thickness

et al. 2022

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“…Finally, 2D domains are extended over time and then stitched together seamlessly to form a mono-oriented continuous film. The GUD strategy has been demonstrated as a very practical growth method for the single-crystalline semimetallic graphene, [14,64,66] semiconducting TMDCs, [72,158] and insulating h-BN films. [77][78][79] One piece of representative literature using the GUD route to prepare the single-crystalline graphene at the wafer-scale was reported in 2014 by the Whang group.…”

Section: Growth Of Unidirectional Domainsmentioning

confidence: 99%

“…[159] Recently, several wafer-scale single-crystalline TMDCs (including WS 2 , MoS 2 , MoSe 2, and WSe 2 ) were successfully grown on vicinal a-plane sapphire by the Liu group, a dualcoupling-guided mechanism was regarded to drive their monoorientated growth features. [158] MoS 2 domains grown with a highly oriented (two directions) feature has also been achieved on epitaxial GaN. [160,161] However, the TMD/nitride heterostructure is yet to be achieved at the wafer scale.…”

Section: Growth Of Unidirectional Domainsmentioning

confidence: 99%

Growth of 2D Materials at the Wafer Scale

Guo

Kim

et al. 2022

Advanced Materials

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der Waals (vdW) layered 2D materials are regarded as a very promising new material system to support postsilicon IC technologies because of their rich and excellent physical properties even with thickness at the atomic scale (<1 nm). [1][2][3] It has been reported that monolayer MoS 2 as a transistor channel can be effectively controlled using 1 nm length carbon nanotube gating. Electric field control on such a short channel can achieve MoS 2 transistors with excellent performance, including an on/off current ratio up to 10 6 and a subthreshold swing (SS) of 65 mV s −1 . [4] This indicates that 2D vdW semiconductors are promising candidates to replace silicon for continued downscaling.Many vdW layered 2D materials have been synthesized and explored since the graphene discovery in 2004. They include highly conductive graphene [1] and MXenes (atomic-thin transition metal carbides and nitrides), [5] transition metal chalcogenides (TMDCs, including both metallic [6] and semiconducting [2] ), 2D elemental semiconductors (black phosphorus (BP), [7] tellurium (Te) [8] ), 2D insulators (e.g., hexagonal boron nitride (h-BN) [9] and some oxides). [10] The large variety of vdW layered 2D materials provides a large potential for advanced 2D electronics.However, for scalable applications, all vdW layered 2D materials face a common challenge: transitioning from micrometer-scale 2D flakes to wafer-scale. [1,2,[11][12][13] This is necessary for scaling up 2D vdW materials application in the high-end semiconductor industry. The history of silicon wafer development and its significant impact on modern information technologies has already demonstrated the importance of a large wafer size for volume production at an acceptable cost. Some materials, such as graphene, [14] h-BN, [15] and TMDCs, [16] have been heavily explored for wafer-scale growth, but the reality is that wafer-scale film quality still has enormous space to improve, especially when compared to chip-grade single-crystalline silicon. Other materials such as MXenes, BP, Te, and vdW oxides, have only a few reported papers focusing on their wafer-scale growth. Hence, we feel that this timely review focusing on wafer-scale growth methods of relevant 2D vdW layered materials is urgently needed.The scope of this review is clarified in Figure 1, where the structures, properties, wafer-scale growth methods, and applications of representative vdW layered 2D materials. We begin by briefly introducing these 2D vdW layered materials and discuss Wafer-scale growth has become a critical bottleneck for scaling up applications of van der Waal (vdW) layered 2D materials in high-end electronics and optoelectronics. Most vdW 2D materials are initially obtained through top-down synthesis methods, such as exfoliation, which can only prepare small flakes on a micrometer scale. Bottom-up growth can enable 2D flake growth over a large area. However, seamless merging of these flakes to form large-area continuous films with well-controlled layer thickness and lattice orientation is still a sign...

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“…Although several reported 2D materials have grown at the wafer scale, most of such attempts are still in the exploratory stage. Moreover, because the several reported 2D material transfer technologies are inefficient and the technical requirements for the operators are very high, it is imminent to prepare high-quality and large-size 2D materials directly on the selected substrate ( Wang et al., 2021 ). In terms of improving the environmental stability of perovskites, appropriate protection strategies, viz., physical encapsulation and chemical passivation are necessary ( Gao et al., 2020 ; Lv et al., 2019 ).…”

Section: Challenges and Outlookmentioning

confidence: 99%

Retinomorphic optoelectronic devices for intelligent machine vision

2022

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Summary Biological visual system can efficiently handle optical information within the retina and visual cortex of the brain, which suggests an alternative approach for the upgrading of the current low-intelligence, large energy consumption, and complex circuitry of the artificial vision system for high-performance edge computing applications. In recent years, retinomorphic machine vision based on the integration of optoelectronic image sensors and processors has been regarded as a promising candidate to improve this phenomenon. This novel intelligent machine vision technology can perform information preprocessing near or even within the sensor in the front end, thereby reducing the transmission of redundant raw data and improving the efficiency of the back-end processor for high-level computing tasks. In this contribution, we try to present a comprehensive review on the recent progress achieved in this emergent field.

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Dual-coupling-guided epitaxial growth of wafer-scale single-crystal WS2 monolayer on vicinal a-plane sapphire

Cited by 187 publications

References 39 publications

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS₂ with Controllable Thickness

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS₂ with Controllable Thickness

Growth of 2D Materials at the Wafer Scale

Retinomorphic optoelectronic devices for intelligent machine vision

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Dual-coupling-guided epitaxial growth of wafer-scale single-crystal WS2 monolayer on vicinal a-plane sapphire

Cited by 187 publications

References 39 publications

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS2 with Controllable Thickness

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS2 with Controllable Thickness

Growth of 2D Materials at the Wafer Scale

Retinomorphic optoelectronic devices for intelligent machine vision

Contact Info

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The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS₂ with Controllable Thickness

The Intrinsic Thermodynamic Difficulty and a Step‐Guided Mechanism for the Epitaxial Growth of Uniform Multilayer MoS₂ with Controllable Thickness