• 文献标题:   How Close Can One Approach the Dirac Point in Graphene Experimentally?
  • 文献类型:   Article
  • 作  者:   MAYOROV AS, ELIAS DC, MUKHIN IS, MOROZOV SV, PONOMARENKO LA, NOVOSELOV KS, GEIM AK, GORBACHEV RV
  • 作者关键词:   graphene, suspended graphene, high mobility, clamped contact
  • 出版物名称:   NANO LETTERS
  • ISSN:   1530-6984 EI 1530-6992
  • 通讯作者地址:   Univ Manchester
  • 被引频次:   120
  • DOI:   10.1021/nl301922d
  • 出版年:   2012

▎ 摘  要

The above question is frequently asked by theorists who are interested in graphene as a model system, especially in context of relativistic quantum physics. We offer an experimental answer by describing electron transport in suspended devices with carrier mobilities of several 10(6) cm(2) V-1 s(-1) and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as approximate to 10(8) cm(-2), allowing a neutral state with a few charge carriers per entire micrometer-scale device. Above liquid helium temperatures, the electronic properties of such devices are intrinsic, being governed by thermal excitations only. This yields that the Dirac point can be approached within 1 meV, a limit currently set by the remaining charge inhomogeneity. No sign of an insulating state is observed down to 1 K, which establishes the upper limit on a possible bandgap.