Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Opening the band gap of graphene through silicon doping for improved
  performance of graphene/GaAs heterojunction solar cells
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess