Two-carrier model on the magnetotransport of epitaxial graphene containing coexisting single-layer and bilayer areas

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.

Keywords:

• Magnetoresistance
• Hall effect
• electronic transport
• AFM
• Epitaxial graphene
• two-carrier model

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 2(b) is obtained with a parameter smaller than in Figure 2(a), at variance with Equation (12(12) ), revealing again the inhomogeneity in the sample. Fairly good fitting can also be achieved by fixing to obtained from Figure 2(a). In the following analysis, we used in Equation (12(12) ).

2 Owing to the excellent fitting shown in Figure 2, uncertainty due to the standard error in the fitting is less than 0.1% of the values shown in the table.

Additional information

Funding

This work was supported by JSPS KAKENHI [grant number JP26400311], [grant number JP25107003].