Electronic transport and flicker noise in graphene structures
Kaverzin, Alexey
Date: 15 November 2011
Thesis or dissertation
Publisher
University of Exeter
Degree Title
PhD in Physics
Abstract
In this thesis the properties of graphene are studied via the various aspects of the
quantum transport: doping of the graphene surface with organic molecules, flicker noise
and transport in the quantum Hall regime.
First, it was shown that certain molecules (toluene, aniline and water), which possess
such common properties as non zero ...
In this thesis the properties of graphene are studied via the various aspects of the
quantum transport: doping of the graphene surface with organic molecules, flicker noise
and transport in the quantum Hall regime.
First, it was shown that certain molecules (toluene, aniline and water), which possess
such common properties as non zero dipole moment and ability to undergo the
electrochemical reaction, have a peculiar doping effect on graphene. The effect of
toluene doping was studied in detail and is explained by the electrochemical reaction,
which takes place in the vicinity of the graphene and results in a gate voltage dependent
doping.
Second, the flicker noise in graphene and its relation to the scattering mechanisms
were studied. The flicker noise as a function of the carrier concentration was demonstrated
to be sensitive to the scattering potential determining the resistance of the
graphene. Therefore, as it was suggested, the flicker noise can be used as a tool for
determining the dominant scattering mechanism in graphene, although it was found
that the resistance and noise can originate from different scattering potentials.
Also, the flicker noise spectrum was shown to decompose into individual lorentzians
at low temperatures (below ∼ 25 K), where the fluctuations of the resistance is supposedly coming from the random jumps of electrons between the conductive channel in the graphene flake and the nearby impurity states.
Third, the transport properties of the bilayer/trilayer graphene structure were studied
at different temperatures and different magnetic fields including the quantum Hall
regime. Bilayer and trilayer parts of the sample revealed the signatures of the quantum
Hall effect predicted theoretically. The transport through the interface between bilayer
and trilayer parts was also investigated. Signatures of the interface resistance were
seen, although the observed behaviour is not explained. Under high magnetic fields
the properties of the interface longitudinal resistance were described qualitatively by
the classic transport equations.
Doctoral Theses
Doctoral College
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