Abstract
We have performed low-temperature magnetotransport measurements on epitaxial graphene composed of domains of single-layer and bilayer areas simultaneously present on SiC(0 0 0 1). Positive magnetoresistance that tends to saturate at high magnetic fields is observed for longitudinal component , while the Hall resistance
exhibits sublinear behaviour. The lineshapes for both
and
can be accounted for extremely well by the semiclassical magnetotransport model incorporating two types of carriers conducting in parallel. Two sets of mobilities and densities, corresponding to single-layer and bilayer regions, respectively, can be obtained by fitting the experimental traces to the two-carrier model formulae. From the carrier densities, in turn, the ratio of the single-layer to bilayer areas can be deduced, assuming the alignment of the Fermi levels in the two types of areas with differing dispersion relations and Dirac point energies. The ratio of areas thus obtained is consistent with the ratio directly observed in the atomic force micrograph.
Acknowledgements
This work was carried out by the joint usage/research program of the Institute of Materials and Systems for Sustainability(IMaSS), Nagoya University.
Notes
No potential conflict of interest was reported by the authors.
1 The best fitting shown in Figure (b) is obtained with a parameter smaller than
in Figure (a), at variance with Equation (Equation12
(12) ), revealing again the inhomogeneity in the sample. Fairly good fitting can also be achieved by fixing
to
obtained from Figure (a). In the following analysis, we used
in Equation (Equation12
(12) ).
2 Owing to the excellent fitting shown in Figure , uncertainty due to the standard error in the fitting is less than 0.1% of the values shown in the table.