Effect of copper surface morphology on grain size uniformity of graphene grown by chemical vapor deposition

An attempt has been made to understand the thermodynamic mechanism study of the low-pressure chemical vapor deposition (LPCVD) process during single-layer graphene (SLG) growth as it is the most debatable part of the CVD process. The intensive studies are being carried out worldwide to enhance the quality of LPCVD-grown graphene up to the level of mechanically exfoliated SLG. The mechanism and processes have been discussed earlier by several research groups during the variation in different parameters. However, the optimization and mechanism involvement due to individual partial pressure-based effects has not been elaborately discussed so far. Hence, we have addressed this issue in detail including thermodynamics of the growth process and tried to establish the effect of the partial pressures of individual gases during the growth of SLG. Also, optical microscopy, Raman spectroscopy, and atomic force microscopy (AFM) have been performed to determine the quality of SLG. Furthermore, nucleation density has also been estimated to understand a plausible mechanism of graphene growth based on partial pressure. Moreover, the field-effect transistor (FET) device has been fabricated to determine the electrical properties of SLG, and the estimated mobility has been found as ∼2595 cm 2 V –1 s –1 at n = −2 × 10 12 cm –2 . Hence, the obtained results trigger that the partial pressure is an important parameter for the growth of SLG and having various potential applications in high-performance graphene FET (GFET) devices.

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“…Several efforts have been made till now to control the nucleation density of graphene grain. 21 − 26 …”

Section: Introductionmentioning

confidence: 99%

“…Quality enhancement can be achieved by decreasing nucleation density during graphene growth by the CVD method. Several efforts have been made till now to control the nucleation density of graphene grain. − …”

Section: Introductionmentioning

confidence: 99%

Partial Pressure Assisted Growth of Single-Layer Graphene Grown by Low-Pressure Chemical Vapor Deposition: Implications for High-Performance Graphene FET Devices

2020

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“…After the development of an analytical resistance model, to verify its applicability for grain-parameter extraction, we synthesized monolayer graphene on a 25-µm-thick Cu foil (99.8% purity, Alfa-Aesar Inc., Ward Hill, MA, USA) by a thermal CVD system (TCVD 100, Scientec Inc., Suwon, South Korea). To grow the polycrystalline graphene layer with uniform-size grains, electropolishing of the Cu surface was first performed in an 85% phosphoric acid bath using a constant voltage of 1.2 V for 20 min [15]. The polished Cu foil was then loaded into the CVD chamber and annealed at 1050 • C for 1 h with a flow of Ar (570 sccm) and H 2 (100 sccm) for surface treatment.…”

Section: Graphene Growth and Transfermentioning

confidence: 99%

Simultaneous Extraction of the Grain Size, Single-Crystalline Grain Sheet Resistance, and Grain Boundary Resistivity of Polycrystalline Monolayer Graphene

Park

Lee

et al. 2022

Nanomaterials

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The electrical properties of polycrystalline graphene grown by chemical vapor deposition (CVD) are determined by grain-related parameters—average grain size, single-crystalline grain sheet resistance, and grain boundary (GB) resistivity. However, extracting these parameters still remains challenging because of the difficulty in observing graphene GBs and decoupling the grain sheet resistance and GB resistivity. In this work, we developed an electrical characterization method that can extract the average grain size, single-crystalline grain sheet resistance, and GB resistivity simultaneously. We observed that the material property, graphene sheet resistance, could depend on the device dimension and developed an analytical resistance model based on the cumulative distribution function of the gamma distribution, explaining the effect of the GB density and distribution in the graphene channel. We applied this model to CVD-grown monolayer graphene by characterizing transmission-line model patterns and simultaneously extracted the average grain size (~5.95 μm), single-crystalline grain sheet resistance (~321 Ω/sq), and GB resistivity (~18.16 kΩ-μm) of the CVD-graphene layer. The extracted values agreed well with those obtained from scanning electron microscopy images of ultraviolet/ozone-treated GBs and the electrical characterization of graphene devices with sub-micrometer channel lengths.

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“…The growth route is characterized by the formation of several islands with incomplete substrate coverage (Figure 5) and can be related to the uneven profile of the Cu surface, where many protrusions were noticed in the AFM image (Figure 3a). Indeed, growth of multilayer graphene was observed to take place preferentially at step edges and ridges on the surface of Cu foils [32,33], leading to insufficient density of carbon adatoms on remaining bare Cu for achieving full surface coverage [31,32].…”

Section: As-plated Cu Substratementioning

confidence: 99%

“…An additional important result of the annealing treatment is the development of a greatly uniform surface (Figure 3b), without a significant number of defects such as marks and step edges, where preferential growth of multilayer graphene can take place [32]. This is a distinctive advantage of the electroformed substrate, considering that rolling marks typical of commercial Cu foils are not eliminated by common annealing treatments [32,33].…”

Section: Annealed Cu Substratementioning

confidence: 99%

Graphene Growth on Electroformed Copper Substrates by Atmospheric Pressure CVD

et al. 2022

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Chemical vapor deposition (CVD) is regarded as the most promising technique for the mass production of graphene. CVD synthesis under vacuum is the most employed process, because the slower kinetics give better control on the graphene quality, but the requirement for high-vacuum equipment heavily affects the overall energy cost. In this work, we explore the possibility of using electroformed Cu substrate as a catalyst for atmospheric-pressure graphene growth. Electrochemical processes can produce high purity, freestanding metallic films, avoiding the surface defects that characterize the rolled foils. It was found that the growth mode of graphene on the electroformed catalyst was related to the surface morphology, which, in turn, was affected by the preliminary treatment of the substrate material. Suitable conditions for growing single layer graphene were identified.

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Effect of copper surface morphology on grain size uniformity of graphene grown by chemical vapor deposition

Cited by 7 publications

References 26 publications

Partial Pressure Assisted Growth of Single-Layer Graphene Grown by Low-Pressure Chemical Vapor Deposition: Implications for High-Performance Graphene FET Devices

Partial Pressure Assisted Growth of Single-Layer Graphene Grown by Low-Pressure Chemical Vapor Deposition: Implications for High-Performance Graphene FET Devices

Simultaneous Extraction of the Grain Size, Single-Crystalline Grain Sheet Resistance, and Grain Boundary Resistivity of Polycrystalline Monolayer Graphene

Graphene Growth on Electroformed Copper Substrates by Atmospheric Pressure CVD

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