Moiré-Modulated Conductance of Hexagonal Boron Nitride Tunnel Barriers

Summerfield, Alex; Kozikov, Aleksey; Cheng, T.S.; Davies, Andrew J.; Cho, Yong-jin; Khlobystov, Andrei N.; Mellor, Christopher J.; Foxon, C. T.; Watanabe, Kenji; Taniguchi, Takashi; Eaves, L.; Novoselov, Konstantin; Новиков, С. В.; Beton, Peter H.

doi:10.1021/acs.nanolett.8b01223

Cited by 23 publications

(28 citation statements)

References 40 publications

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“…Our conducting AFM measurements on the electrical resistivity of MBEgrown hBN monolayers 33,39 is consistent with earlier measurements on monolayers, exfoliated from high quality bulk a) Electronic mail: Sergei.Novikov@nottingham.ac.uk hBN crystals. 4,15 The high optical quality of our hBN grown at high temperatures on highly oriented pyrolytic graphite (HOPG) has been confirmed by both spectroscopic ellipsometry and photoluminescence spectroscopy.…”

Section: Introductionsupporting

confidence: 89%

“…33,37 Using AFM we also observe hexagonal moir e patterns, consistent with the close rotational alignment of the hBN lattice and the graphite substrate. 33,39 In this paper, we present our recent results on the hightemperature PA-MBE growth of hBN monolayers with atomically controlled thicknesses for 2D applications and on the growth of significantly thicker hBN layers for potential DUV applications.…”

Section: Introductionmentioning

confidence: 99%

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High-temperature molecular beam epitaxy of hexagonal boron nitride layers

Cheng¹,

Summerfield²,

Mellor³

et al. 2018

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The growth and properties of hexagonal boron nitride (hBN) have recently attracted much attention due to applications in graphene-based monolayer thick two dimensional (2D)-structures and at the same time as a wide band gap material for deep-ultraviolet device (DUV) applications. The authors present their results in the high-temperature plasma-assisted molecular beam epitaxy (PA-MBE) of hBN monolayers on highly oriented pyrolytic graphite substrates. Their results demonstrate that PA-MBE growth at temperatures ∼1390 °C can achieve mono- and few-layer thick hBN with a control of the hBN coverage and atomically flat hBN surfaces which is essential for 2D applications of hBN layers. The hBN monolayer coverage can be reproducible controlled by the PA-MBE growth temperature, time and B:N flux ratios. Significantly thicker hBN layers have been achieved at higher B:N flux ratios. The authors observed a gradual increase of the hBN thickness from 40 to 70 nm by decreasing the growth temperature from 1390 to 1080 °C. However, by decreasing the MBE growth temperature below 1250 °C, the authors observe a rapid degradation of the optical properties of hBN layers. Therefore, high-temperature PA-MBE, above 1250 °C, is a viable approach for the growth of high-quality hBN layers for 2D and DUV applications.

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Section: Introductionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

High-temperature molecular beam epitaxy of hexagonal boron nitride layers

Cheng¹,

Summerfield²,

Mellor³

et al. 2018

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

Self Cite

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“…Recently, Liao et al fabricated bilayer MoS2/graphene heterojunctions by an epitaxial growth method, controlled an AFM tip to push the monolayer MoS2, and studied the rotation angle dependence of the average conductivity . Moreover, although local density of states (LDOS) at the surface of twisted 2D materials has been previously investigated using scanning tunneling microscope (STM), little research has been conducted on the mechanism of interlayer contact conductance in t‐BLG, especially down to the atomic‐level . It is still unclear how the atomic stacking configurations of twisted bilayer 2D materials affect the local interlayer contact conductance.…”

Section: Introductionmentioning

confidence: 99%

Understanding Interlayer Contact Conductance in Twisted Bilayer Graphene

Song

Sun

et al. 2019

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Bilayer or few‐layer 2D materials showing novel electrical properties in electronic device applications have aroused increasing interest in recent years. Obtaining a comprehensive understanding of interlayer contact conductance still remains a challenge, but is significant for improving the performance of bilayer or few‐layer 2D electronic devices. Here, conductive atomic force microscope (C‐AFM) experiments are reported to explore the interlayer contact conductance between bilayer graphene (BLG) with various twisted stacking structures fabricated by the chemical vapor deposition (CVD) method. The current maps show that the interlayer contact conductance between BLG strongly depends on the twist angle. The interlayer contact conductance of 0° AB‐stacking bilayer graphene (AB‐BLG) is ≈4 times as large as that of 30° twisted bilayer graphene (t‐BLG), which indicates that the twist angle–dependent interlayer contact conductance originates from the coupling–decoupling transitions. Moreover, the moiré superlattice‐level current images of t‐BLG show modulations of local interlayer contact conductance. Density functional theory calculations together with a theoretical model reproduce the C‐AFM current map and show that the modulation is mainly attributed to the overall contribution of local interfacial carrier density and tunneling barrier.

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“…However, if the topmost layer is free of defects, one might expect that the reaction terminates after total conversion of the first layer, or proceeds layer by layer. This in itself could be a useful approach for producing large area h‐BN layers on top of graphene, and may be useful as a 2D gate dielectric, tunnel barrier, or for encapsulation of epitaxial graphene devices . Furthermore, based on the higher chemical reactivity of monolayer graphene on SiC, due to the influence of the buffer layer, we speculate that the substitution reaction proceeds faster on graphene monolayers compared to multilayers.…”

mentioning

confidence: 97%