How close can one approach the Dirac point in graphene experimentally?
Nano Lett
; 12(9): 4629-34, 2012 Sep 12.
Article
em En
| MEDLINE
| ID: mdl-22935053
ABSTRACT
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 ≈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.
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MEDLINE
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Grafite
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Modelos Químicos
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article