Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Point Defects and Grain Boundaries in Rotationally Commensurate MoS2 on
  Epitaxial Graphene   With reduced degrees of freedom, structural defects are expected to play a
greater role in two-dimensional materials in comparison to their bulk
counterparts. In particular, mechanical strength, electronic properties, and
chemical reactivity are strongly affected by crystal imperfections in the
atomically thin limit. Here, ultra-high vacuum (UHV) scanning tunneling
microscopy (STM) and spectroscopy (STS) are employed to interrogate point and
line defects in monolayer MoS2 grown on epitaxial graphene (EG) at the atomic
scale. Five types of point defects are observed with the majority species
showing apparent structures that are consistent with vacancy and interstitial
models. The total defect density is observed to be lower than MoS2 grown on
other substrates, and is likely attributed to the van der Waals epitaxy of MoS2
on EG. Grain boundaries (GBs) with 30{\deg} and 60{\deg} tilt angles resulting
from the rotational commensurability of MoS2 on EG are more easily resolved by
STM than atomic force microscopy at similar scales due to the enhanced contrast
from their distinct electronic states. For example, band gap reduction to ~0.8
eV and ~0.5 eV is observed with STS for 30{\deg} and 60{\deg} GBs,
respectively. In addition, atomic resolution STM images of these GBs are found
to agree well with proposed structure models. This work offers quantitative
insight into the structure and properties of common defects in MoS2, and
suggests pathways for tailoring the performance of MoS2/graphene
heterostructures via defect engineering.

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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat