Abstract:Reproducible dry and wet transfer techniques were developed to improve the transfer of large-area monolayer graphene grown on copper foils by chemical vapor deposition (CVD). The techniques reported here allow transfer onto three different classes of substrates: substrates covered with shallow depressions, perforated substrates, and flat substrates. A novel dry transfer technique was used to make graphene-sealed microchambers without trapping liquid inside. The dry transfer technique utilizes a polydimethylsil… Show more
“…On the other hand, CVD growth of graphene on catalytic metals, such as Cu [21] and Ni [17,21,311], is a promising approach for efficient large-scale production of defect-free graphene with controllable number of layers. Moreover, the resulting monolayer graphene can be easily transferred to arbitrary substrates [312]. Therefore, this section would concentrate on the generation of defects during graphene synthesis in the CVD process.10.1080/14686996.2018.1494493-F0016Figure 16.Fabrication of monolayer graphene by (a) mechanical exfoliation [320], (b) reduction of GO [353], (c) epitaxial growth [354] and (d) CVD growth [321,312].…”
Section: Disorders In Graphene Structurementioning
confidence: 99%
“…polymethylmethacrylate (PMMA)) to support the graphene while etching the metal catalyst away in an etchant [312]. Polymer-on-graphene layer is then transferred to a specified substrate, followed by dissolution of the polymer layer.…”
Section: Disorders In Graphene Structurementioning
Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.
“…On the other hand, CVD growth of graphene on catalytic metals, such as Cu [21] and Ni [17,21,311], is a promising approach for efficient large-scale production of defect-free graphene with controllable number of layers. Moreover, the resulting monolayer graphene can be easily transferred to arbitrary substrates [312]. Therefore, this section would concentrate on the generation of defects during graphene synthesis in the CVD process.10.1080/14686996.2018.1494493-F0016Figure 16.Fabrication of monolayer graphene by (a) mechanical exfoliation [320], (b) reduction of GO [353], (c) epitaxial growth [354] and (d) CVD growth [321,312].…”
Section: Disorders In Graphene Structurementioning
confidence: 99%
“…polymethylmethacrylate (PMMA)) to support the graphene while etching the metal catalyst away in an etchant [312]. Polymer-on-graphene layer is then transferred to a specified substrate, followed by dissolution of the polymer layer.…”
Section: Disorders In Graphene Structurementioning
Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analyzed subsequently. Finally, we review previous work on the modulation of structural defects in graphene for specific applications.
“…The moiré superstructure shows that the lattice constant of the h-BN layer is approximately 2.56 Å, approximately 2% larger than the in-plane lattice constant of bulk h-BN, 2.51 Å. 24,25 Thus, the moiré superstructure suggests that the h-BN layer is under tensile stress on the SiC substrate. When the single-crystal h-BN layer was heated above 1150 ℃, the spot positions in the LEED pattern gradually moved from that of 2% stretched h-BN to graphene, and subsequently to a pattern corresponding to unstrained h-BN; the (5 × 5) LEED 6 pattern gradually disappeared and, subsequently, a moiré LEED pattern with R0° around the LEED spots of graphene emerged (see Figure 1d-f and Figure S1 in Supporting Information).…”
Vertical and lateral heterogeneous structures of two-dimensional (2D) materials have paved the way for pioneering studies on the physics and applications of 2D materials. A hybridized hexagonal boron nitride (h-BN) and graphene lateral structure, a heterogeneous 2D structure, has been fabricated on single-crystal metals or metal foils by chemical vapor deposition (CVD).However, once fabricated on metals, the h-BN/graphene lateral structures require an additional transfer process for device applications, as reported for CVD graphene grown on metal foils. Here, we demonstrate that a single-crystal h-BN/graphene lateral structure can be epitaxially grown on a wide-gap semiconductor, SiC(0001). First, a single-crystal h-BN layer with the same orientation as bulk SiC was grown on a Si-terminated SiC substrate at 850 ℃ using borazine molecules.Second, when heated above 1150 ℃ in vacuum, the h-BN layer was partially removed and, subsequently, replaced with graphene domains. Interestingly, these graphene domains possess the same orientation as the h-BN layer, resulting in a single-crystal h-BN/graphene lateral structure on a whole sample area. For temperatures above 1600 ℃ , the single-crystal h-BN layer was completely replaced by the single-crystal graphene layer. The crystalline structure, electronic band structure, and atomic structure of the h-BN/graphene lateral structure were studied by using low energy electron diffraction, angle-resolved photoemission spectroscopy, and scanning tunneling microscopy, respectively. The h-BN/graphene lateral structure fabricated on a wide-gap semiconductor substrate can be directly applied to devices without a further transfer process, as reported for epitaxial graphene on a SiC substrate.
“…Chemical vapor deposition (CVD) grown graphene from the copper foil was transferred onto this device using standard transfer techniques. 37 The transferred graphene layer was typically p-doped. Graphene was then patterned by electron beam lithography and oxygen plasma to avoid contact with the aluminum pad on the n + doping region.…”
The gate-controllability of the Fermi-edge onset of interband absorption in graphene can be utilized to modulate near-infrared radiation in the telecommunication band. However, a high modulation efficiency has not been demonstrated to date, because of the small amount of light absorption in graphene. Here, we demonstrate a ~40% amplitude modulation of 1.55 µm radiation with gated single-layer graphene that is coupled with a silicon micro-ring resonator. Both the quality factor and resonance wavelength of the silicon micro-ring resonator were strongly modulated through gate tuning of the Fermi level in graphene.These results promise an efficient electro-optic modulator, ideal for applications in large-scale on-chip optical interconnects that are compatible with complementary metal-oxide-semiconductor technology.
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