Graphene Epitaxial Growth on SiC(0001) for Resistance Standards

Abstract

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 • C-2000 • 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.

Low Carrier Density Epitaxial Graphene Devices On SiC

“…Recently, growth of homogeneous monolayer EG on the Si‐face of SiC has been improved by optimizing the annealing temperature and background gas conditions . QHE plateaus have been observed in various magneto‐transport measurements and the robust quantized Hall resistance (QHR) plateau with filling factor , where i = 0 is the lowest Landau level (LL) index for monolayer graphene, has been shown to be equivalent to that of conventional 2D electron systems based on semiconductor heterostructures at low temperature (<4 K), which are the basis of present‐day electrical resistance metrology .…”

“…Five samples diced from semi‐insulating 4H‐ or 6H‐SiC(0001) wafers were annealed at 1900 °C or 1950 °C in an Ar background at 101–105 kPa using a controlled Si sublimation process (see supporting information) . Raman microscopy shows that homogeneous graphene covers 95% of the central sample area for samples prepared by the same methods and under similar conditions.…”

Fabrication and Study of Large-Area QHE Devices Based on Epitaxial Graphene

“…In recent years, significant progress has been achieved in the precision measurement of the quantum Hall effect (QHE) in devices based on epitaxial graphene films grown on SiC [1][2][3][4]. Results obtained on large area QHE devices [3] fabricated from epitaxial graphene film showed that the quantization of the Hall resistance in magnetic field as low as 2.5 T is possible due to the application of a photochemical gating [5] which leads to a reduction of the carrier concentration down to 6·10 10 cm -2 .…”

Epitaxial graphene homogeneity and quantum Hall effect in millimeter-scale devices

“…1a). This face-to-graphite 17 (FTG) method leads to uniform EG growth with limited terrace restructuring on clean, low-miscut, chemically-mechanically polished SiC(0001) substrates 18 , and often results in crescent-shaped terraces having small areas and low aspect ratios, as shown in Fig. 1b.…”

“…We have found that this terrace topography, together with the near-equilibrium FTG environment, supports more isotropic carbon diffusion compared to parallel, linear terraces, thus reducing the tendency to form extended bilayer ribbons. Annealing samples at T > 1800 °C with two SiC(0001) surfaces arranged face-to-face 18,19 results in uncontrolled step-bunching of the terraces (see Supplement Fig. S1a,b).…”