Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct imaging of the band profile in single layer ${\small MoS_2}$ on
  graphite: quasiparticle energy gap, metallic edge states and edge band
  bending   Using Scanning Tunneling Microscopy and Spectroscopy, we probe the electronic
structures of single layer ${\small MoS_2}$ on graphite. We show that the
quasiparticle energy gap of single layer ${\small MoS_2}$ is 2.15 $\pm$ 0.07 eV
at 77 K. Combining with temperature dependent photoluminescence studies, we
deduce an exciton binding energy of 0.22 $\pm$ 0.1 eV, a value that is much
lower than current theoretical predictions. Consistent with theoretical
predictions we directly observed metallic edge states of single layer ${\small
MoS_2}$. In the bulk region of ${\small MoS_2}$, the Fermi level is located at
1.8 eV above the valence band maximum, possibly due to the formation of a
graphite/${\small MoS_2}$ heterojunction. At the edge, however, we observe an
upward band bending of 0.6 eV within a short depletion length of about 5 nm,
analogous to the phenomena of Fermi level pinning of a 3D semiconductor by
metallic surface states.

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The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
3
The categories of this paper are: physics