Imaging edges of nanostructured graphene

dehisceforkΗλεκτρονική - Συσκευές

2 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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Imaging edges
of nanostructured
graphene

J. Kling, A.
Cagliani, T. J. Booth, P. Bøggild, J. B. Wagner, T. W. Hansen


Graphene, as the
forefather
of 2D
-
materials, attracts much attention due to its
extraordinary properties like transparency, flexibility and outstanding high conductivity,
together with a thickness of only one atom.
However,

g
raphene
also
possesses no band
gap
,

which makes it unsuitab
le for many electronic
applications

like transistors.

It has
been shown theoretically that by nanostructuring pristine graphene, e.g. with regular
holes, the electronic properties can be tuned and a band gap
introduced
. The size,
distance and edge terminat
ion of these “defects” influence the adaptability
.

Such
nanostructuring can be done experimentally, but especially characterization

at atomic
level

is a huge challenge.


High
-
resolution TEM (HRTEM) is used to characterize the atomic structure of graphene.
W
e optimized the imaging conditi
ons

used

for the FEI Titan ETEM.
To reduce the
knock
-
on damage of the carbon atoms in the graphene structure, the microscope was
operated

at 80kV. As this strongly increases the influence of the chromatic aberration of
the l
enses, the energy spread of the electron gun
was
reduced

to <0.2eV b
y using
a

monochromator. Together with the
objective
-
lens
Cs
-
corrector a resolution better then
1.2Å can be
achieved
, which
allows

us

to resolve the second order reflection of
graphene and

to visualize the atomic structure in
HRTEM. With this tool we tackle the
challenge of imaging the introduced “defects” and their atomic structure.