Band Bending and Valence Band Quantization at Line Defects in MoS2

Clifford Murray, Camiel van Efferen, Wouter Jolie, Jeison Antonio Fischer, Joshua Hall, Achim Rosch, Arkady V. Krasheninnikov, Hannu Pekka Komsa, Thomas Michely

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

The variation of the electronic structure normal to 1D defects in quasi-freestanding MoS2, grown by molecular beam epitaxy, is investigated through high resolution scanning tunneling spectroscopy at 5 K. Strong upward bending of valence and conduction bands toward the line defects is found for the 4|4E mirror twin boundary and island edges but not for the 4|4P mirror twin boundary. Quantized energy levels in the valence band are observed wherever upward band bending takes place. Focusing on the common 4|4E mirror twin boundary, density functional theory calculations give an estimate of its charging, which agrees well with electrostatic modeling. We show that the line charge can also be assessed from the filling of the boundary-localized electronic band, whereby we provide a measurement of the theoretically predicted quantized polarization charge at MoS2 mirror twin boundaries. These calculations elucidate the origin of band bending and charging at these 1D defects in MoS2. The 4|4E mirror twin boundary not only impairs charge transport of electrons and holes due to band bending, but holes are additionally subject to a potential barrier, which is inferred from the independence of the quantized energy landscape on either side of the boundary.

Original languageEnglish
Pages (from-to)9176-9187
Number of pages12
JournalACS Nano
Volume14
Issue number7
DOIs
Publication statusPublished - 28 Jul 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • band bending
  • mirror twin boundary
  • MoS2
  • polarization charge
  • scanning tunnelling spectroscopy

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