Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Raman spectrum and optical extinction of graphene buffer layers on the
  Si-face of 6H-SiC   The buffer layer has been analysed by combined micro-Raman and
micro-transmission experiments. The epitaxial graphene growth on the (0001) Si
face of 6H-SiC substrates was tuned to get a mixed surface at the early stage
of graphitization with i) bare SiC, ii) buffer layer and iii) in some localized
areas small monolayers flakes on top of the buffer layer. These unique samples
enabled to measure the Raman spectrum of the buffer layer (close to the Raman
spectrum of a carbon layer with a significant percentage of sp3 bonds) and its
corresponding relative extinction at 514.5 nm. The Raman spectrum of the buffer
layer remains visible after the growth of one monolayer on top but, despite the
relatively low absorption coefficient of graphene, the Raman intensity is
strongly reduced (typically divided by 3). The buffer layer background will
bias usual evaluations of the domain sizes based on the D/G integrated
intensities ratio. Finally, several Raman maps show the excellent thickness
uniformity and crystalline quality of the graphene monolayers and that they are
subjected to a non uniform compressive strain with values comprised between
-0.60% and -0.42%.

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The categories of this paper are: bayes-an
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math