Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Apparent Differences between Single Layer Molybdenum Disulfide
  Fabricated via Chemical Vapor Deposition and Exfoliation   Innovative applications based on two-dimensional solids require
cost-effective fabrication processes resulting in large areas of high quality
materials. Chemical vapour deposition is among the most promising methods to
fulfill these requirements. However, for 2D materials prepared in this way it
is generally assumed that they are of inferior quality in comparison to the
exfoliated 2D materials commonly used in basic research. In this work we
challenge this assumption and aim to quantify the differences in quality for
the prototypical transition metal dichalcogenide MoS$_2$. To this end single
layers of MoS$_2$ prepared by different techniques (exfoliation, grown by
different chemical vapor deposition methods, transfer techniques, and as
vertical heterostructure with graphene) are studied by Raman and
photoluminescence spectroscopy, complemented by atomic force microscopy. We
demonstrate that as-prepared MoS$_2$, directly grown on SiO$_2$, differs from
exfoliated MoS$_2$ in terms of higher photoluminescence, lower electron
concentration, and increased strain. As soon as a water film is intercalated
(e.g., by transfer) underneath the grown MoS$_2$, in particular the
(opto-)electronic properties become practically identical to those of
exfoliated MoS$_2$. A comparison of the two most common precursors shows that
the growth with MoO$_3$ causes greater strain and/or defect density deviations
than growth with ammonium heptamolybdate. As part of a heterostructure directly
grown MoS$_2$ interacts much stronger with the substrate, and in this case an
intercalated water film does not lead to the complete decoupling, which is
typical for exfoliation or transfer. Our work shows that the supposedly poorer
quality of grown 2D transition metal dichalcogenides is indeed a misconception.

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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con