Physics of a disordered Dirac point in epitaxial graphene from temperature-dependent magnetotransport measurements
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 7, 075407- p.Article in journal (Refereed) Published
We report a study of disorder effects on epitaxial graphene in the vicinity of the Dirac point by magnetotransport. Hall effect measurements show that the carrier density increases quadratically with temperature, in good agreement with theoretical predictions which take into account intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. We deduce disorder strengths in the range 10.2-31.2 meV, depending on the sample treatment. We investigate the scattering mechanisms and estimate the impurity density to be 3.0-9.1x10(10) cm(-2) for our samples. A scattering asymmetry for electrons and holes is observed and is consistent with theoretical calculations for graphene on SiC substrates. We also show that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations.
Place, publisher, year, edition, pages
American Physical Society , 2015. Vol. 92, no 7, 075407- p.
IdentifiersURN: urn:nbn:se:liu:diva-120861DOI: 10.1103/PhysRevB.92.075407ISI: 000359047600004OAI: oai:DiVA.org:liu-120861DiVA: diva2:849448
Funding Agencies|U.K. EPSRC; NMS, E.U. Graphene Flagship [CNECT-ICT-604391]; EMRP Graph Ohm; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; China Scholarship Council2015-08-282015-08-282015-09-08