Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride

Xue, Jiamin; Sanchez-Yamagishi, Javier; Bulmash, Daniel; Jacquod, Philippe; Deshpande, Aparna; Watanabe, Kenji; Taniguchi, Takashi; Jarillo‐Herrero, Pablo; LeRoy, Brian J.

doi:10.1038/nmat2968

Cited by 1,205 publications

(1,226 citation statements)

References 33 publications

Supporting

Mentioning

1,154

Contrasting

Unclassified

Order By: Relevance

“…The stacking angle between graphene and h‐BN layers was observed to be 26° for 0.55 nm period 39. Electronic states of graphene were supported by the inert and flat h‐BN layers, similar to that of intrinsic graphene 33, 40, 41. d I /d V spectrum was determined by the scanning tunneling spectroscopy (STS) analysis which in turn was conducted through Moiré pattern region of 0.55 nm (Figure 4d).…”

Section: Catalyst‐free Direct Cvd Growth Of Graphene On Technologicalmentioning

confidence: 99%

Direct CVD Growth of Graphene on Technologically Important Dielectric and Semiconducting Substrates

et al. 2018

View full text Add to dashboard Cite

To fabricate graphene based electronic and optoelectronic devices, it is highly desirable to develop a variety of metal‐catalyst free chemical vapor deposition (CVD) techniques for direct synthesis of graphene on dielectric and semiconducting substrates. This will help to avoid metallic impurities, high costs, time consuming processes, and defect‐inducing graphene transfer processes. Direct CVD growth of graphene on dielectric substrates is usually difficult to accomplish due to their low surface energy. However, a low‐temperature plasma enhanced CVD technique could help to solve this problem. Here, the recent progress of metal‐catalyst free direct CVD growth of graphene on technologically important dielectric (SiO2, ZrO2, HfO2, h‐BN, Al2O3, Si3N4, quartz, MgO, SrTiO3, TiO2, etc.) and semiconducting (Si, Ge, GaN, and SiC) substrates is reviewed. High and low temperature direct CVD growth of graphene on these substrates including growth mechanism and morphology is discussed. Detailed discussions are also presented for Si and Ge substrates, which are necessary for next generation graphene/Si/Ge based hybrid electronic devices. Finally, the technology development of the metal‐catalyst free direct CVD growth of graphene on these substrates is concluded, with future outlooks.

show abstract

Section: Catalyst‐free Direct Cvd Growth Of Graphene On Technologicalmentioning

confidence: 99%

Direct CVD Growth of Graphene on Technologically Important Dielectric and Semiconducting Substrates

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The growth of large‐area high‐quality graphene films is fundamental for the upcoming graphene applications. Chemical vapour deposition (CVD) method offers good prospects to produce large‐size graphene films due to its simplicity, controllability and cost‐efficiency 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75. Many researches have verified that graphene can be catalytically grown on metallic substrates, like ruthenium (Ru),13, 14 iridium (Ir),15, 16 platinum (Pt),17, 18, …”

Section: Introductionmentioning

confidence: 99%

The Way towards Ultrafast Growth of Single‐Crystal Graphene on Copper

Zhang

Qiu

et al. 2017

Advanced Science

View full text Add to dashboard Cite

The exceptional properties of graphene make it a promising candidate in the development of next‐generation electronic, optoelectronic, photonic and photovoltaic devices. A holy grail in graphene research is the synthesis of large‐sized single‐crystal graphene, in which the absence of grain boundaries guarantees its excellent intrinsic properties and high performance in the devices. Nowadays, most attention has been drawn to the suppression of nucleation density by using low feeding gas during the growth process to allow only one nucleus to grow with enough space. However, because the nucleation is a random event and new nuclei are likely to form in the very long growth process, it is difficult to achieve industrial‐level wafer‐scale or beyond (e.g. 30 cm in diameter) single‐crystal graphene. Another possible way to obtain large single‐crystal graphene is to realize ultrafast growth, where once a nucleus forms, it grows up so quickly before new nuclei form. Therefore ultrafast growth provides a new direction for the synthesis of large single‐crystal graphene, and is also of great significance to realize large‐scale production of graphene films (fast growth is more time‐efficient and cost‐effective), which is likely to accelerate various graphene applications in industry.

show abstract

“…The valley current in BLG decreases through intervalley scattering, which requires a large momentum transfer (e.g., by atomic scale disorders). Such disorders are found to be Page 8 of 16 extremely rare in cleaved BLG crystals 19,20 , implying a large valley diffusion length 21,22 . In the present study, an appreciable nonlocal signal was observed in samples up to 10 m long.…”

mentioning

confidence: 99%

Gate-tunable topological valley transport in bilayer graphene

et al. 2015

View full text Add to dashboard Cite

Valley pseudospin, the quantum degree of freedom characterizing the degenerate valleys in energy bands 1 , is a distinct feature of two-dimensional Dirac materials [1][2][3][4][5] . Similar to spin, the valley pseudospin is spanned by a time reversal pair of states, though the two valley pseudospin states transform to each other under spatial inversion. The breaking of inversion symmetry induces various valley-contrasted physical properties; for instance, valley-dependent topological transport is of both scientific and technological interests [2][3][4][5] . Bilayer graphene (BLG) is a unique system whose intrinsic inversion symmetry can be controllably broken by a perpendicular electric field, offering a rare possibility for continuously tunable valley-topological transport. Here, we used a perpendicular gate electric field to break the inversion symmetry in BLG, and a giant nonlocal response was observed as a result of the topological transport of the valley pseudospin. We further showed that the valley transport is fully tunable by external gates, and that the nonlocal signal persists up to room temperature and over long distances. These observations challenge contemporary understanding of topological transport in a gapped system, and the robust topological transport may lead to future valleytronic applications.In crystalline solids, a topological current can be induced by the Berry phase of the electronic wave function 6 . Examples include the quantum Hall current in a magnetic field, and the spin Hall current arising from spin-orbit coupling. Such topological transport is robust against impurities and defects in materials -a feature that is much sought after in potential electronic applications. In such applications, the ability to switch and to continuously tune the topological transport is crucial. The topological current is in principle dictated by the crystal symmetry, which is difficult to change in Page 3 of 16 bulk materials. Bilayer graphene, however, offer new opportunities in which inversion symmetry can be controllably broken by an external electric field in the perpendicular direction.The topological current controlled by the inversion symmetry breaking is associated with carriers' valley pseudospin, which characterises the two-fold degenerate band-edges located at the corners of the hexagonal Brillouin zone. The topological Hall current, odd under time-reversal but even under inversion, is strictly zero in pristine mono-and bi-layer graphene which respect both symmetries. When the inversion symmetry is broken, however, time-reversal symmetry requires the Hall currents to have opposite signs and equal magnitudes in the two valleys (i.e., a valley The nonlocal transport persists up to room temperature and over long distances (up to 10 m). Our results represent major progress in the quest for a robust, tunable valley pseudospin system among various alternatives [3][4][5]11,12 , and indicate the possibility of using the nonlocal topological transport in practical applications under ambient conditio...

show abstract

Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride

Cited by 1,205 publications

References 33 publications

Direct CVD Growth of Graphene on Technologically Important Dielectric and Semiconducting Substrates

Direct CVD Growth of Graphene on Technologically Important Dielectric and Semiconducting Substrates

The Way towards Ultrafast Growth of Single‐Crystal Graphene on Copper

Gate-tunable topological valley transport in bilayer graphene

Contact Info

Product

Resources

About