Effect of Substrate Roughness and Feedstock Concentration on Growth of Wafer-Scale Graphene at Atmospheric Pressure

Abstract

The growth of large-area graphene on catalytic metal substrates is a topic of both fundamental and technological interest. We have developed an atmospheric pressure chemical vapor deposition (CVD) method that is potentially more cost-effective and compatible with industrial production than approaches based on synthesis under high vacuum. Surface morphology of the catalytic Cu substrate and the concentration of carbon feedstock gas were found to be crucial factors in determining the homogeneity and electronic transport properties of the final graphene film. The use of an electropolished metal surface and low methane concentration enabled the growth of graphene samples with single layer content exceeding 95%. Field effect transistors fabricated from CVD graphene made with the optimized process had room temperature hole mobilities that are a factor of 2−5 larger than those measured for samples grown on as-purchased Cu foil with larger methane concentration. A kinetic model is proposed to explain the observed dependence of graphene growth on catalyst surface roughness and carbon source concentration.

Synthesis of graphene

“…6). Surface roughness is known to produce graphene thickness variation on copper [143,144]. Since graphene growth on copper is surface limited, so smoothness Here dark purple areas highlighted by black arrows displays that even on low carbon solubility metal like copper, corrugations on starting substrate can result in formation of significant multilayer regions along with monolayer graphene [45].…”

Large-Scale Synthesis of High-Quality Hexagonal Boron Nitride Nanosheets for Large-Area Graphene Electronics

“…12 The quality of a thin film grown on a metal by surface adsorption is strongly affected by the surface morphology, as previously reported in the case of the graphene growth mechanism on a Cu foil. 22,23 In this regard, we introduced two methods (thermal annealing (TA) and thermal The h-BN nanosheets grown on the Cu foils were transferred onto SiO 2 (300 nm thick)/Si wafer as shown in Figure 2d−f. The number of impurity particles in the h-BN nanosheets grown on the TA-treated Cu foil is slightly decreased as compared to that in the h-BN nanosheets grown on the pristine Cu foil (Figure 2d,e).…”

Overlook of current chemical vapor deposition-grown large single-crystal graphene domains

“…One of the most profound surface features on a Cu substrate is a rolling mark introduced by cold rolling during the manufacturing process. The most common means of eliminating rolling marks is electro-polishing [44,45]. However, this has proved to be ineffective and insufficient to suppress the nucleation density because, although electro-polishing removes many surface irregularities, there are many other sites at which graphene can nucleate, preventing any significant reduction of the nucleation density.…”