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Dipartimento di Scienze

CVD Graphene on Ge substrates

Oratore prof.ssa Luciana Di Gaspare, Univ. Roma Tre
Data 05/03/2018 - 14:30
Luogo Aula A - Via della Vasca Navale 84
The route towards the implementation of graphene in “real world”
microelectronic applications exploiting the exceptional graphene
properties comprises the development of scalable deposition
techniques. Chemical vapor deposition is deemed as one of the most
promising techniques to achieve graphene crystals. At now, two major
hurdles in the advancement towards a CMOS-compatible, graphene-based
microelectronic platform are present: the achievement of metal-free
graphene and the further improvements in the graphene quality. The
growth of graphene directly on Ge or Ge/Si substrates (in particular
on the technology relevant (001) surface orientation) recently
demonstrated could be a breakthrough toward CMOS compatibility, since
no catalytic metal surfaces are required. We will present the results
of our study of the CVD graphene growth process on Ge(001) substrate.
We investigated the kinetic of the growth by a combined use of
µ-Raman, x-ray photoelectron spectroscopies, scanning electron and
scanning tunneling microscopies. We were able to establish different
growth regimes–yielding to graphene nanoribbons, graphene deposited
in a layer by layer regime and graphene multilayer–by simply varying
the carbon precursor flow. In the layer-by-layer growth regime,
reliable and well controlled growth of graphene monolayer with quality
exceeding the state of the art for graphene synthesis on Ge is
obtained. We also investigated the early stage of CVD graphene
synthesis which deeply influences the resulting graphene quality. We
identified the carbon precursor phase to graphene nucleation, made of
C aggregates with different size, shape and local ordering. The C
precursor phase evolves gradually towards graphene domains through a
crystallization process that ultimately results in the formation of a
uniform single layer graphene.