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A well-controlled technique for high-temperature epitaxial growth on 6H-SiC(0001) substrates is shown to allow the development of monolayer graphene that exhibits promise for precise metrological applications. Face-to-face and face-to-graphite annealing in a graphite-lined furnace at 1200 ^\circ\C–2000 ^\circ\C with a 101-kPa Ar background gas lowers the rates of SiC decomposition and Si sublimation/diffusion and thus provides a means to control the rate of graphene layer development. We studied a wide range of growth temperatures and times and describe the resulting sample surface morphology changes and graphene layer structures. The experimental results are compared to a kinetic model based on two diffusion processes: Si vapor diffusion in the Ar-filled gap and atomic diffusion through graphitic surface layers. [ABSTRACT FROM PUBLISHER]

Quantized magnetotransport is observed in 5.6 × 5.6 mm 2 epitaxial graphene devices, grown using highly constrained sublimation on the Si-face of SiC(0001) at high temperature (1900 °C). The precise quantized Hall resistance of R x y = h 2 e 2 is maintained up to record level of critical current I xx = 0.72 mA at T = 3.1 K and 9 T in a device where Raman microscopy reveals low and homogeneous strain. Adsorption-induced molecular doping in a second device reduced the carrier concentration close to the Dirac point ( n ≈ 10 10 cm −2 ), where mobility of 18760 cm 2 /V is measured over an area of 10 mm 2 . Atomic force, confocal optical, and Raman microscopies are used to characterize the large-scale devices, and reveal improved SiC terrace topography and the structure of the graphene layer. Our results show that the structural uniformity of epitaxial graphene produced by face-to-graphite processing contributes to millimeter-scale transport homogeneity, and will prove useful for scientific and commercial applications. [ABSTRACT FROM AUTHOR]