Graphene: It is all about the toppings
To fully exploit the potential of the'wonder material' graphene, it has
to be combined with other materials

Date:
July 8, 2020
Source:
Vienna University of Technology
Summary:
The way graphene interacts with other materials depends on how
these materials are brought into contact with the graphene. The
appropriate atoms are brought into contact with the graphene in
such a way that they 'grow' on the graphene in the desired crystal
structure. Until now the mechanisms of the 'growth' of such other
materials on graphene have often remained unclear. A new study
shows now how indium oxide grows on graphene.



FULL STORY ========================================================================== Graphene consists of a single layer of carbon atoms. Exceptional
electronic, thermal, mechanical and optical properties have made graphene
one of the most studied materials at the moment. For many applications in electronics and energy technology, however, graphene must be combined with other materials: Since graphene is so thin, its properties drastically
change when other materials are brought into direct contact with it.


========================================================================== However, combining graphene with other materials at the molecular level
is difficult: The way graphene interacts with other materials depends not
only on which material you choose, but also on how these materials are
brought into contact with the graphene. Rather than sticking a finished material layer to the graphene, the appropriate atoms are brought into
contact with the graphene in such a way that they "grow" on the graphene
in the desired crystal structure.

Until now the mechanisms of the "growth" of such other materials on
graphene have often remained unclear. A new joint study by research
teams from the TU Wien and the University of Vienna for the first time
observes now how indium oxide grows on graphene. The combination of
indium oxide with graphene is important, for example for displays and
sensors. The results have now been presented in the scientific journal "Advanced Functional Materials".

Graphene pizza "As with a pizza, graphene technology is not only dependent
on the graphene pizza base but also on its toppings," explains Bernhard
C. Bayer from the Institute of Materials Chemistry at the TU Wien,
who led the study. "How these toppings are applied to the graphene
is, however, crucial." In most cases, atoms in the gaseous state
are condensed on the graphene. In the case of indium oxide, these are
indium and oxygen. "But there are many parameters such as background
pressure, temperature or the speed at which these atoms are directed
at the graphene that influence the result drastically," says Bernhard
Bayer. "It is therefore important to develop a fundamental understanding
of the chemical and physical processes that actually take place.

But to do this, you have to watch the growth process as it proceeds. "
This is exactly what the research team has now succeeded in doing: for
the first time, the individual steps of growing indium oxide on graphene
were observed in the electron microscope at atomic resolution.

Randomly distributed or perfectly aligned "What was particularly
interesting for us was the observation that, depending on the background pressure, the indium oxide crystallites either arrange themselves randomly
on the graphene's crystal lattice or snap perfectly on one another like
Lego bricks. This difference in arrangement can have a major impact
on the application properties of the combined materials," says Kenan
Elibol, first author of the study. The new findings will be useful to
make the integration of graphene with other materials more predictable
and controllable with respect to future application requirements.


========================================================================== Story Source: Materials provided
by Vienna_University_of_Technology. Original written by Florian
Aigner. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Kenan Elibol, Clemens Mangler, Tushar Gupta, Georg Zagler,
Dominik Eder,
Jannik C. Meyer, Jani Kotakoski, Bernhard C. Bayer. Process Pathway
Controlled Evolution of Phase and Van‐der‐Waals Epitaxy
in In/In 2 O 3 on Graphene Heterostructures. Advanced Functional
Materials, 2020; 2003300 DOI: 10.1002/adfm.202003300 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200708105910.htm

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