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High-speed roll-to-roll manufacturing of graphene using a concentric tube CVD reactor.

Polsen ES, McNerny DQ, Viswanath B, Pattinson SW, John Hart A - Sci Rep (2015)

Bottom Line: We show that a smooth isothermal transition between the reducing and carbon-containing atmospheres, enabled by injection of the carbon feedstock via radial holes in the inner tube, is essential to high-quality roll-to-roll graphene CVD.We discuss how the foil quality and microstructure limit the uniformity of graphene over macroscopic dimensions.We conclude by discussing means of scaling and reconfiguring the CTCVD design based on general requirements for 2-D materials manufacturing.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University of Michigan, 2350 Hayward St., Ann Arbor, MI 48109, USA.

ABSTRACT
We present the design of a concentric tube (CT) reactor for roll-to-roll chemical vapor deposition (CVD) on flexible substrates, and its application to continuous production of graphene on copper foil. In the CTCVD reactor, the thin foil substrate is helically wrapped around the inner tube, and translates through the gap between the concentric tubes. We use a bench-scale prototype machine to synthesize graphene on copper substrates at translation speeds varying from 25 mm/min to 500 mm/min, and investigate the influence of process parameters on the uniformity and coverage of graphene on a continuously moving foil. At lower speeds, high-quality monolayer graphene is formed; at higher speeds, rapid nucleation of small graphene domains is observed, yet coalescence is prevented by the limited residence time in the CTCVD system. We show that a smooth isothermal transition between the reducing and carbon-containing atmospheres, enabled by injection of the carbon feedstock via radial holes in the inner tube, is essential to high-quality roll-to-roll graphene CVD. We discuss how the foil quality and microstructure limit the uniformity of graphene over macroscopic dimensions. We conclude by discussing means of scaling and reconfiguring the CTCVD design based on general requirements for 2-D materials manufacturing.

No MeSH data available.


Benefit of continuous thermal processing with direct transition from a reducing to carbon-containing atmosphere. a) Raman spectra of Cu foil strips that were translated from upstream of the furnace to the annealing zone (black), from the annealing zone to the growth zone (red), and from the growth zone to the exit (downstream) of the furnace (blue). The sample sequentially exposed to the annealing and growth zones shows the best result, and growth does not occur in the annealing zone only. b) Comparison of Raman spectra for CTCVD processing with both zones to processing with the growth zone only.
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f5: Benefit of continuous thermal processing with direct transition from a reducing to carbon-containing atmosphere. a) Raman spectra of Cu foil strips that were translated from upstream of the furnace to the annealing zone (black), from the annealing zone to the growth zone (red), and from the growth zone to the exit (downstream) of the furnace (blue). The sample sequentially exposed to the annealing and growth zones shows the best result, and growth does not occur in the annealing zone only. b) Comparison of Raman spectra for CTCVD processing with both zones to processing with the growth zone only.

Mentions: To isolate the influence of each zone of the reactor, experiments were performed by moving the Cu foil from selected points spanning from upstream to downstream of the heated region, resulting in the Raman spectra shown in Fig. 5a. The portion of Cu foil that started upstream of the furnace and was stopped in the annealing zone did not have graphene present; the Cu that started in the annealing zone and ended in the growth zone exhibited high quality graphene; and the Cu location that started in the growth zone (i.e., was heated while exposed to the carbon precursor) and ended downstream of the furnace had low quality graphene. Thus, we conclude that it is important to heat the Cu foil while exposing it to a non-carbon atmosphere, and to transition to the carbon atmosphere at elevated temperature. The benefit of downstream hydrocarbon injection is also illustrated in Fig. 5b. Here we compare results with a single zone CTCVD design (i.e., H2/C2H4 injected in the annular gap from the input of the system, no downstream holes) and two treatment zones (normal CTCVD configuration). Downstream injection yields roughly 2.7x and 1.8x increases in I2D/IG and IG/ID respectively, relative to the single-zone design. The importance of an isothermal transition from a reducing atmosphere to a carbon-containing atmosphere was also highlighted in a recent study that used a diffusion barrier (Al2O3 on Ni) to prevent carbon exposure until the elevated temperature was reached in a single-zone system39.


High-speed roll-to-roll manufacturing of graphene using a concentric tube CVD reactor.

Polsen ES, McNerny DQ, Viswanath B, Pattinson SW, John Hart A - Sci Rep (2015)

Benefit of continuous thermal processing with direct transition from a reducing to carbon-containing atmosphere. a) Raman spectra of Cu foil strips that were translated from upstream of the furnace to the annealing zone (black), from the annealing zone to the growth zone (red), and from the growth zone to the exit (downstream) of the furnace (blue). The sample sequentially exposed to the annealing and growth zones shows the best result, and growth does not occur in the annealing zone only. b) Comparison of Raman spectra for CTCVD processing with both zones to processing with the growth zone only.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440526&req=5

f5: Benefit of continuous thermal processing with direct transition from a reducing to carbon-containing atmosphere. a) Raman spectra of Cu foil strips that were translated from upstream of the furnace to the annealing zone (black), from the annealing zone to the growth zone (red), and from the growth zone to the exit (downstream) of the furnace (blue). The sample sequentially exposed to the annealing and growth zones shows the best result, and growth does not occur in the annealing zone only. b) Comparison of Raman spectra for CTCVD processing with both zones to processing with the growth zone only.
Mentions: To isolate the influence of each zone of the reactor, experiments were performed by moving the Cu foil from selected points spanning from upstream to downstream of the heated region, resulting in the Raman spectra shown in Fig. 5a. The portion of Cu foil that started upstream of the furnace and was stopped in the annealing zone did not have graphene present; the Cu that started in the annealing zone and ended in the growth zone exhibited high quality graphene; and the Cu location that started in the growth zone (i.e., was heated while exposed to the carbon precursor) and ended downstream of the furnace had low quality graphene. Thus, we conclude that it is important to heat the Cu foil while exposing it to a non-carbon atmosphere, and to transition to the carbon atmosphere at elevated temperature. The benefit of downstream hydrocarbon injection is also illustrated in Fig. 5b. Here we compare results with a single zone CTCVD design (i.e., H2/C2H4 injected in the annular gap from the input of the system, no downstream holes) and two treatment zones (normal CTCVD configuration). Downstream injection yields roughly 2.7x and 1.8x increases in I2D/IG and IG/ID respectively, relative to the single-zone design. The importance of an isothermal transition from a reducing atmosphere to a carbon-containing atmosphere was also highlighted in a recent study that used a diffusion barrier (Al2O3 on Ni) to prevent carbon exposure until the elevated temperature was reached in a single-zone system39.

Bottom Line: We show that a smooth isothermal transition between the reducing and carbon-containing atmospheres, enabled by injection of the carbon feedstock via radial holes in the inner tube, is essential to high-quality roll-to-roll graphene CVD.We discuss how the foil quality and microstructure limit the uniformity of graphene over macroscopic dimensions.We conclude by discussing means of scaling and reconfiguring the CTCVD design based on general requirements for 2-D materials manufacturing.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University of Michigan, 2350 Hayward St., Ann Arbor, MI 48109, USA.

ABSTRACT
We present the design of a concentric tube (CT) reactor for roll-to-roll chemical vapor deposition (CVD) on flexible substrates, and its application to continuous production of graphene on copper foil. In the CTCVD reactor, the thin foil substrate is helically wrapped around the inner tube, and translates through the gap between the concentric tubes. We use a bench-scale prototype machine to synthesize graphene on copper substrates at translation speeds varying from 25 mm/min to 500 mm/min, and investigate the influence of process parameters on the uniformity and coverage of graphene on a continuously moving foil. At lower speeds, high-quality monolayer graphene is formed; at higher speeds, rapid nucleation of small graphene domains is observed, yet coalescence is prevented by the limited residence time in the CTCVD system. We show that a smooth isothermal transition between the reducing and carbon-containing atmospheres, enabled by injection of the carbon feedstock via radial holes in the inner tube, is essential to high-quality roll-to-roll graphene CVD. We discuss how the foil quality and microstructure limit the uniformity of graphene over macroscopic dimensions. We conclude by discussing means of scaling and reconfiguring the CTCVD design based on general requirements for 2-D materials manufacturing.

No MeSH data available.