Electromagnetic induction heating for single crystal graphene growth: morphology control by rapid heating and quenching

Abstract

The direct observation of single crystal graphene growth and its shape evolution is of fundamental importance to the understanding of graphene growth physicochemical mechanisms and the achievement of wafer-scale single crystalline graphene. Here we demonstrate the controlled formation of single crystal graphene with varying shapes, and directly observe the shape evolution of single crystal graphene by developing a localized-heating and rapid-quenching chemical vapor deposition (CVD) system based on electromagnetic induction heating. Importantly, rational control of circular, hexagonal, and dendritic single crystalline graphene domains can be readily obtained for the first time by changing the growth condition. Systematic studies suggest that the graphene nucleation only occurs during the initial stage, while the domain density is independent of the growth temperatures due to the surface-limiting effect. In addition, the direct observation of graphene domain shape evolution is employed for the identification of competing growth mechanisms including diffusion-limited, attachment-limited, and detachment-limited processes. Our study not only provides a novel method for morphology-controlled graphene synthesis, but also offers fundamental insights into the kinetics of single crystal graphene growth.C hemical vapor deposition (CVD) has enabled the growth of single layer graphene over large area through the optimization of synthesis conditions 1-3 , including hydrogen and carbon precursors flow rates 4-6 , surface oxygen 7 , substrate 8,9 , temperature 10 , and pressure 11 . In order to achieve large size and high-quality single crystal graphene, a fundamental understanding of precise mechanisms that governs the formation of graphene domains is necessary. Much effort has been placed on the investigation of graphene growth kinetics by using carbon isotope labeling technique 7,12,13 , or the empirical parameters-controlled methods based on the nucleation and growth theory 14 . It has been widely accepted that the graphene growing process mainly involves surface catalytic reaction for catalyst with low-carbon solubility 1,13 . In this case, graphene nucleation on catalyst surface is one of the critical steps in the growth process. Various factors affect the initiation of graphene nucleation process, including the type or surface morphology of catalyst 15,16 , carbon source 17 , carbon segregation from metalcarbon melts 18 , and parameters in CVD growth 2,19,20 . In general, nucleation densities on polycrystal Cu substrates are nonuniform, representing a key problem in high quality graphene film synthesis. Recently it has been found that uniform nucleation distribution, low nucleation density and highly ordered single crystal graphene films can be obtained by using liquid Cu film as catalytic, which is possibly due to the elimination of Cu grain boundaries 21,22 . However, the direct insight of single crystal graphene growth and its corresponding domain shape evolution during the growth process are still lacking. The chall...

Graphene Synthesis by Inductively Heated Copper Foils: Reactor Design and Operation

“…As depicted by Figure 3, adding hydrogen and/or methane to the argon increases h. In these conditions, when changing the gases required for the thermal annealing and/or nucleation and growth of graphene, the current in the turns must be adjusted to maintain a given temperature on the substrate. For an average frequency of ω = 220 kHz, we calculated the electrical current needed to maintain the substrate temperature at 1050 °C by solving Equation (10). Note that radiative heat losses depend on copper emissivity, which is sensitive to the surface state.…”

“…The inductive heating CVD method has been used previously for growing graphene [8][9][10] and carbon nanotubes [11]. Sosnowchik et al [11] proposed an inductive heating method for the synthesis of carbon nanotubes (CNTs) in a room temperature environment.…”

“…Based on a detailed parametric study for the CVD growth, a two-step growth process was established and the resulting graphene domain size was approximately 90 µm. Wu et al [10] proposed a method based on electromagnetic induction heating for controlled formation of single-crystal graphene. Direct observation of the graphene growth was performed.…”

Solution-processed flexible blue organic light emitting diodes using graphene anode

“…However, the rising price of indium, the brittle properties and degradation of optoelectronic performance over time due to indium diffusion limited the development of OLEDs on flexible substrates [2][3][4][5]. For flexible device applications, as a substitution for ITO, graphene has been identified as a strong potential material for transparent and flexible conductor due to its mechanical robustness, high charge carrier mobility, high optical transparency and high flexibility [6][7][8][9][10]. Nevertheless, graphene as anode for organic optoelectronic devices has been limited in practical applications owing to its low work function, low conductivity and rough surface morphology caused by the transfer residues in comparison with commercial ITO [11,12].…”

Graphene synthesis by microwave plasma chemical vapor deposition: analysis of the emission spectra and modeling

“…However, in most T-CVD processes, the catalyst is heated by the entire reaction chamber volume through a hot-wall reactor, which is obviously less energy efficient and incompatible with scaling up the process. An alternative approach is to inductively heat the metal catalyst via magnetic fields [62][63][64]. This approach enables a high heating rate [62]; however, the chemical activation of the gas phase is limited to the substrate vicinity, i.e., at temperatures near the melting point of copper (~1050°C).…”