Relation between growth rate and structure of graphene grown in a 4″ showerhead chemical vapor deposition reactor

Bekdüz, Bilge; Beckmann, Yannick; Meier, J.; Rest, J.; Mertin, W.; Bacher, G.

doi:10.1088/1361-6528/aa68a8

Cited by 6 publications

(5 citation statements)

References 23 publications

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“…[ 30 ] As a result, when P (CH 4 ) is high, the graphene growth is fast, leading to less time for the defects to be healed and subsequently, to a high defect density. [ 31–33 ]…”

Section: Resultsmentioning

confidence: 99%

“…[30] As a result, when P(CH 4 ) is high, the graphene growth is fast, leading to less time for the defects to be healed and subsequently, to a high defect density. [31][32][33] Figure 1c demonstrates the effect of CVD temperature on the density of the intrinsic defects, where I D /I G is larger for graphene grown at 800 °C (blue) than for that grown at 900 °C (orange). According to ab initio calculations, the defect formation energy at the front-most graphene edge is 1.3 eV, while the energy barrier associated with defect healing is 1.86 eV.…”

Section: Formation Of Intrinsic Graphene Poresmentioning

confidence: 99%

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Direct Chemical Vapor Deposition Synthesis of Porous Single‐Layer Graphene Membranes with High Gas Permeances and Selectivities

Yuan

Faucher

et al. 2021

Advanced Materials

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yield orders of magnitude higher gas permeances because of its atomic thickness and low cross-membrane transport resistance. [3,4] Because perfect single-layer graphene is almost impermeable to gases, [5,6] in-plane pores, which are vacancy defects in the graphene lattice, are necessary for gas permeation. To realize the enormous potential of porous graphene for gas separation, the areal pore density in graphene should be considerably high. Our group theoretically predicted that the pore density needs to exceed 10 14 m −2 for a graphene membrane to surpass the Robeson upper bound for polymers. [7,8] Further, to enable selective gas transport, the pore sizes in the graphene membrane should be precisely controlled such that they are commensurate with the gas molecular sizes. In fact, the pore sizes in porous graphene are typically widely distributed and fitted by a lognormal distribution, where a small fraction of larger pores determine the total gas permeance. [9][10][11][12] As a result, an even higher pore density is needed for porous graphene to achieve a high gas permeance with enough competitiveness. Etching away atoms from pristine graphene has been the most widely applied strategy to increase the pore density in a graphene membrane. High-energy ion or electron bombardment was used to perforate graphene in some early studies. [12][13][14][15] Later, chemical oxidative etching was developed as a more scalable graphene perforation method. [16][17][18] For example, He et al. used O 2 plasma to perforate as-synthesized graphene from chemical vapor deposition (CVD) and measured a H 2 /CH 4 selectivity > 15. [11] Zhao et al. exposed pristine graphene to O 2 plasma for a short pore nucleation burst, and then to mild O 3 etching for controllable pore expansion, in order to partially decouple the pore nucleation and growth and to obtain a narrow pore size distribution. [19] However, despite the efforts made to decouple the pore nucleation and growth, the correlation between them still exists for those etching-based methods. Because the nucleation and growth of the pores are both triggered by etching (e.g., O 2 plasma), one needs to raise the energy intensity of the etching reaction to increase the pore density, which in turn generates larger, less selective pores. This Single-layer graphene containing molecular-sized in-plane pores is regarded as a promising membrane material for high-performance gas separations due to its atomic thickness and low gas transport resistance. However, typical etching-based pore generation methods cannot decouple pore nucleation and pore growth, resulting in a trade-off between high areal pore density and high selectivity. In contrast, intrinsic pores in graphene formed during chemical vapor deposition are not created by etching. Therefore, intrinsically porous graphene can exhibit high pore density while maintaining its gas selectivity. In this work, the density of intrinsic graphene pores is systematically controlled for the first time, while appropriate pore sizes for gas sieving are ...

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“…[ 30 ] As a result, when P (CH 4 ) is high, the graphene growth is fast, leading to less time for the defects to be healed and subsequently, to a high defect density. [ 31–33 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Formation Of Intrinsic Graphene Poresmentioning

confidence: 99%

Direct Chemical Vapor Deposition Synthesis of Porous Single‐Layer Graphene Membranes with High Gas Permeances and Selectivities

Yuan

Faucher

et al. 2021

Advanced Materials

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“…The copper foils were then dipped in deionized water and ethanol for one minute and blown dry by nitrogen. The corresponding process is discussed elsewhere [28]. We induced a DC plasma with a TruPlasma DC4001 Generator with a pulse frequency of up to 100 kHz between two electrodes.…”

Section: Experimental Methodsmentioning

confidence: 99%

Graphene growth through a recrystallization process in plasma enhanced chemical vapor deposition

et al. 2018

Self Cite

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Thermal chemical vapor deposition (TCVD) is the current method of choice to fabricate high quality, large area graphene films on catalytic copper substrates. In order to obtain sufficiently high growth rates at reduced growth temperatures an efficient dissociation of the precursor molecules already in the gas phase is required. We used plasma enhanced chemical vapor deposition (PECVD) to fabricate high quality graphene films at various temperatures. The efficient, plasma-induced dissociation of the precursor molecules results in an activation energy of 2.2 eV for the growth rate in PECVD, which is reduced by almost a factor of 2 compared to TCVD growth in the same reactor. By varying the growth time, we demonstrate that crystalline graphene grains surrounded by amorphous carbon formed during the early stage of growth merge into an almost defect-free graphene film with growth time via a recrystallization process. Almost defect-free graphene is prepared with negligible (I /I < 0.1) contributions of the D peak in Raman spectroscopy and with a sheet resistance down to 470 Ω/sq.

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“…Controllable, reproducible, and scalable growth of graphene and related 2D materials remains the foremost challenge for both research and any technologies exploiting their unique properties. The chemical vapor deposition (CVD) of graphene and hexagonal boron nitride (h-BN) on transition metal catalysts has become the most widespread growth method for large monolayer domain size and large-area continuous films. − The ever increasing uptake of such CVD is driven by simple reactor designs, high tolerance parameter spaces, and the relatively low costs. Significant progress has been made in understanding the key underlying reaction mechanisms underpinning such graphene and h-BN CVD. ,,− Specifically for catalysts of low carbon solubility such as Cu, the introduction of oxygen via partial preoxidation of the catalyst and/or a gaseous precursor during the CVD process is known to have a range of beneficial effects. ,,,,,,,− Oxygen has been shown to be highly effective in removing pre-existing deleterious carbon and thus enable orders of magnitude lower graphene nucleation densities. , Thus, large graphene domain sizes can be achieved which are required for emerging industrial applications; particularly in electronics and photonics.…”

Section: Introductionmentioning

confidence: 99%

The Role and Control of Residual Bulk Oxygen in the Catalytic Growth of 2D Materials

et al. 2019

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We systematically study the effects of residual oxygen in the bulk of Cu foil catalysts on the chemical vapour deposition (CVD) of graphene. While oxidation is widely used to remove impurities in metal catalysts and to control the nucleation density of graphene, we show that minute concentrations of residual bulk oxygen can significantly deteriorate the quality of as-grown graphene highlighted by an increased Raman D/G ratio, increased propensity to post-growth etching and increased fraction of multi-layer graphene nucleation. Starting from commercial Cu foils, we show that a simple hydrogen annealing step after the initial oxidation allows us to lower the residual oxygen level as measured by time-of-flight secondary ion mass spectrometry to produce graphene of significantly higher quality. This can be effectively combined with a short hydrocarbon exposure time of 10 min to achieve near full mono-layer graphene coverage, suitable for emerging industrial applications. We show that residual oxygen can have an equally significant impact on Fe catalysed h-BN CVD, and discuss the underlying mechanisms with parallels to well-known processes in metallurgy, catalysis and vacuum science.

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Relation between growth rate and structure of graphene grown in a 4″ showerhead chemical vapor deposition reactor

Cited by 6 publications

References 23 publications

Direct Chemical Vapor Deposition Synthesis of Porous Single‐Layer Graphene Membranes with High Gas Permeances and Selectivities

Direct Chemical Vapor Deposition Synthesis of Porous Single‐Layer Graphene Membranes with High Gas Permeances and Selectivities

Graphene growth through a recrystallization process in plasma enhanced chemical vapor deposition

The Role and Control of Residual Bulk Oxygen in the Catalytic Growth of 2D Materials

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