New Journal of Physics (Jan 2023)

The transport properties of Kekulé-ordered graphene p–n junction

  • Peipei Zhang,
  • Chao Wang,
  • Yu-Xian Li,
  • Lixue Zhai,
  • Juntao Song

DOI
https://doi.org/10.1088/1367-2630/ad091d
Journal volume & issue
Vol. 25, no. 11
p. 113021

Abstract

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The transport properties of electrons in graphene p – n junction with uniform Kekulé lattice distortion have been studied using the tight-binding model and the Landauer–Büttiker formalism combined with the nonequilibrium Green’s function method. In the Kekulé-ordered graphene, the original K and K ʹ valleys of the pristine graphene are folded together due to the $\sqrt{3} \times \sqrt{3}$ enlargement of the primitive cell. When the chiral symmetry breaking of a valley leads to a single-valley phase, there are special transport properties of Dirac electrons in the Kekulé lattice. In the O-shaped Kekulé graphene p – n junction, Klein tunneling is suppressed, and only resonance tunneling occurs. In the Y-shaped Kekulé graphene p – n junction, the transport of electrons is dominated by Klein tunneling. When the on-site energy modification is introduced into the Y-shaped Kekulé structure, both Klein tunneling and resonance tunneling occur, and the electron tunneling is enhanced. Under strong magnetic fields, the conductance of O-shaped and on-site energy-modified Y-shaped Kekulé graphene p – n junctions is non-zero due to the presence of resonance tunneling. It is also found that the disorder can enhance conductance, with conductance plateaus forming in the appropriate range of disorder strength.

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