The growth of single-layer graphene on Cu metal by chemical vapor deposition (CVD) is a versatile method for synthesizing high-quality, large-area graphene. It is known that high CVD temperatures, close to the Cu melting temperature (1083 °C), are effective for the growth of large graphene domains, but the growth dynamics of graphene over the high-temperature Cu surface is not clearly understood. We investigated the surface dynamics of the single-layer graphene growth by using heteroepitaxial Cu(111) and Cu(100) films. At relatively lower temperatures, 900–1030 °C, the as-grown graphene showed the identical orientation with the underlying Cu(111) lattice. However, when the graphene was grown above 1040 °C, a new stable configuration of graphene with 3.4° rotation became dominant. This slight rotation is interpreted by the enhanced graphene–Cu interaction due to the formation of long-range ordered structure. Further increase of the CVD temperature resulted in graphene which is rotated with wide angle distr...
Last. Young Hee Lee(SKKU: Sungkyunkwan University)H-Index: 126
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Seamless stitching of graphene domains, on polished copper (111) is proved clearly not only at atomic scale by scanning tunnelling microscopy (STM) and transmission electron micoscopy (TEM), but also at the macroscale by optical microscopy after UV-treatment. Using this concept of seamless stitching, synthesis of 6 cm × 3 cm monocrystalline graphene without grain boundaries on polished copper (111) foil is possible, which is only limited by the chamber size.
The epitaxial growth of graphene on catalytically active metallic surfaces via chemical vapor deposition (CVD) is known to be one of the most reliable routes toward high-quality large-area graphene. This CVD-grown graphene is generally coupled to its metallic support resulting in a modification of its intrinsic properties. Growth on oxides is a promising alternative that might lead to a decoupled graphene layer. Here, we compare graphene on a pure metallic to graphene on an oxidized copper surfa...
The largest applications of high-performance graphene will likely be realized when combined with ubiquitous Si very large scale integrated (VLSI) technology, affording a new portfolio of “back end of the line” devices including graphene radio frequency transistors, heat and transparent conductors, interconnects, mechanical actuators, sensors, and optical devices. To this end, we investigate the scalable growth of polycrystalline graphene through chemical vapor deposition (CVD) and its integratio...
We report the scalable growth of aligned graphene and hexagonal boron nitride on commercial copper foils, where each film originates from multiple nucleations yet exhibits a single orientation. Thorough characterization of our graphene reveals uniform crystallographic and electronic structures on length scales ranging from nanometers to tens of centimeters. As we demonstrate with artificial twisted graphene bilayers, these inexpensive and versatile films are ideal building blocks for large-scale...
During the chemical vapor deposition (CVD) growth of graphene, graphene domains grown on a Cu surface merge together and form a uniform graphene sheet. For high-performance electronics and other applications, it is important to understand the interfacial structure of the merged domains, as well as their influence on the physical properties of graphene. We synthesized large hexagonal graphene domains with controlled orientations on a heteroepitaxial Cu film and studied the structure and propertie...
Last. Dongmok Whang(SKKU: Sungkyunkwan University)H-Index: 30
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The uniform growth of single-crystal graphene over wafer-scale areas remains a challenge in the commercial-level manufacturability of various electronic, photonic, mechanical, and other devices based on graphene. Here, we describe wafer-scale growth of wrinkle-free single-crystal monolayer graphene on silicon wafer using a hydrogen-terminated germanium buffer layer. The anisotropic twofold symmetry of the germanium (110) surface allowed unidirectional alignment of multiple seeds, which were merg...
#1Yufeng Hao(University of Texas at Austin)H-Index: 44
#2M. S. Bharathi(Institute of High Performance Computing Singapore)H-Index: 14
Last. Rodney S. Ruoff(University of Texas at Austin)H-Index: 165
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The growth of high-quality single crystals of graphene by chemical vapor deposition on copper (Cu) has not always achieved control over domain size and morphology, and the results vary from lab to lab under presumably similar growth conditions. We discovered that oxygen (O) on the Cu surface substantially decreased the graphene nucleation density by passivating Cu surface active sites. Control of surface O enabled repeatable growth of centimeter-scale single-crystal graphene domains. Oxygen also...
Integration of functional organic molecules with graphene is expected to promote the development of graphene-based flexible electronics with novel properties. Here, the self-assembled structure of dipole phthalocyanine molecules, chloro-aluminum phthalocyanine (ClAlPc), on single-layer graphene grown by chemical vapor deposition (CVD) over a Cu film was characterized by low-temperature scanning tunneling microscopy (LT-STM). The phthalocyanine molecules show highly ordered assembled structures o...
In this paper we discuss the effect of background pressure and synthesis temperature on the graphene crystal sizes in chemical vapor deposition (CVD) on copper catalyst. For the first time, we quantitatively demonstrate a fundamental role of the background pressure and provide the activation energy for graphene nucleation in atmospheric pressure CVD (9 eV), which is substantially higher than for the low pressure CVD (4 eV). We attribute the difference to a greater importance of copper sublimatio...
#2Han-Na Hwang(POSTECH: Pohang University of Science and Technology)H-Index: 9
Last. Chan-Cuk Hwang(POSTECH: Pohang University of Science and Technology)H-Index: 17
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Copper is considered to be the most promising substrate for the growth of high-quality and large area graphene by chemical vapor deposition (CVD), in particular, on the (111) facet. Because the interactions between graphene and Cu substrates influence the orientation, quality, and properties of the synthesized graphene, we studied the interactions using angle-resolved photoemission spectroscopy. The evolution of both the Shockley surface state of the Cu(111) and the π band of the graphene was me...
Last. Toh-Ming Lu(RPI: Rensselaer Polytechnic Institute)H-Index: 71
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There has been increasing interest in the fabrication of thin film materials with mixed dimensions, in particular, 2D to 3D and 3D to 2D heterostructures. Often, if the interface interaction is weak, the lattice matching criterion between the substrate and overlayer can be lifted. If the overlayer lattice is completely relaxed, it can form an incommensurate film on the mismatched substrate. In this work, we show that domain boundaries are inherent in the incommensurate epitaxial films due to ran...
This is an investigation about the influence of synthesis conditions of graphene oxide (GO) such as KMnO4 concentration and H2SO4/H3PO4 ratio on the structural and electrochemical properties of the Pt/rGO nanocatalyst produced based on gamma irradiation. The catalytic characterizations were evaluated by cyclic voltammetry (CV), impedance spectroscopy (EIS), chronoamperometry (CA), XRD, TEM, FTIR, and Raman. The Pt/rGO for 0.01 g/ml of KMNO4 (Pt-G0.01 K) exhibited the highest stability and anodic...
Abstract Abnormal grain growth of polycrystalline iron (Fe) foil up to grains of 1 cm × 2.2 cm in size, is reported. Pre-strain generated by plastic deformation promoted the abnormal grain growth during post-strain annealing, resulting in large area regions close to single crystal within the foil. The number of nucleus/nuclei and maximum grain size for the abnormal grain growth were highly affected by the plastic deformation conditions as they cause different stored energies in the foils. These ...
Last. Zhongfan Liu(PKU: Peking University)H-Index: 126
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Single-crystal metals are promising substrates for the epitaxial growth of two-dimensional (2D) materials owing to the absence of grain boundaries and distinctive symmetries. The rich arrangements of atoms on various crystal facets serve as an ideal platform for cutting-edge research on regulating the structures of the as-grown 2D materials. However, it is challenging to obtain large single-crystal metal materials, which hinders the in-depth exploration of single-crystal metal-2D material interf...
#2Jianlong Liu(University of Electronic Science and Technology of China)H-Index: 7
Last. Li-Ming Liu(University of Electronic Science and Technology of China)H-Index: 2
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Single-crystal graphene has attracted much attention due to its excellent electrical properties in recent years, and many growth methods have been proposed, including the copper pockets method. In the copper pockets method, a piece of copper foil is folded into a pocket and put into a chemical vapor deposition (CVD) system for the growth of graphene. The dynamic balance of evaporation and deposition of copper on the inner surfaces of the copper pockets avoids high surface roughness caused by the...
Last. Hiroki Hibino(Kwansei Gakuin University)H-Index: 38
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In-situ X-ray diffraction was used to investigate initial stages of GaN growth on graphene-covered SiO2 substrates with or without AlN buffer layers by plasma-assisted molecular beam epitaxy. The in-plane lattice parameter of GaN remained almost constant during growth without AlN buffer layers, confirming weak interactions between GaN and graphene. On the substrate with AlN buffer layers, the GaN lattice parameter continuously changed from AlN value to GaN value, indicating that the AlN islands ...
Last. Di Zhang(SJTU: Shanghai Jiao Tong University)H-Index: 70
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Abstract The prosperity of graphene in the past decade has provided us with both a versatile platform for scientific studies and a multitude of solutions for technological applications. Interfacing graphene with bulk metals is fundamental for a wide range of interesting multi-dimensional systems ranging from incorporating graphene into fully dense metal matrices, and graphene epitaxy on metal substrates to the deposition of metal overlayers on graphene. The microstructure, interaction and proper...
Last. Zhongfan Liu(PKU: Peking University)H-Index: 126
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: Grain boundaries produced during material synthesis affect both the intrinsic properties of materials and their potential for high-end applications. This effect is commonly observed in graphene film grown using chemical vapor deposition and therefore caused intense interest in controlled growth of grain-boundary-free graphene single crystals in the past ten years. The main methods for enlarging graphene domain size and reducing graphene grain boundary density are classified into single-seed an...
