Concerted Chemical-Mechanical
Reaction in Catalyzed
Growth of Confined Graphene Layers into Hexagonal Disks
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Abstract
Graphene and graphite synthesis of uniform films is becoming
routine,
so now efforts are turning to grow specific patterns or complex structures.
More research is needed with regard to the practical aspects of the
growth of graphene layers, especially as it relates to self-assembled
structures. We used gallium-catalyzed thermal decomposition of silicon
carbide to understand spatially confined growth. Growing graphene
layers push on a large step in hard silicon carbide (SiC) with significant
force, as observed by high-resolution transmission electron microscopy
of film cross sections. Alternatively multiple graphitic layers can
grow into disks embedded in silicon carbide if the crystal is heated
above the transition to plastic deformation. Euler buckling appears
to limit the size and deformation of the silicon carbide crystal to
produce graphitic flakes with an oriented hexagonal shape. These results
illustrate the effect of the mechanical force of growing graphene
in confined spaces: the growing graphene can be redirected, graphene
can deform the confining barrier, or growth of graphene can be limited.
This also provides a route for fabrication of masses of homogeneous,
hexagonal disks of graphite with dimensions that are tuned by directed
self-assembly