Local Conduction in MoxW1- xSe2: The Role of Stacking Faults, Defects, and Alloying

Pantelis Bampoulis* (Corresponding Author), Kai Sotthewes, Martin H. Siekman, Harold J.W. Zandvliet

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)
196 Downloads (Pure)

Abstract

Here, we report on the surface conductivity of WSe2 and MoxW1-xSe2 (0 ≤ x ≤ 1) crystals investigated with conductive atomic force microscopy. We found that stacking faults, defects, and chemical heterogeneities form distinct two-dimensional and one-dimensional conduction paths on the transition metal dichalcogenide surface. In the case of WSe2, in addition to step edges, we find a significant amount of stacking faults (formed during the cleaving process) that strongly influence the surface conductivity. These regions are attributed to the alternation of the 2H and 3R polytypism. The stacking faults form regular 2D patterns by alternation of the underlying stacking order, with a periodicity that varies significantly between different regions and samples. In the case of MoxW1-xSe2, its conductivity has a localized nature, which depends on the underlying chemical composition and the Mo/W ratio. Segregation to W-rich and Mo-rich regions during the growth process leads to nonuniform conduction paths on the surface of the alloy. We found a gradual change of the conductivity moving from one region to the other, reminiscent of lateral band bending. Our results demonstrate the use of C-AFM as a nanoscopic tool to probe the electrical properties of largely inhomogeneous samples and show the complicated nature of the surface conductivity of TMDC alloys.

Original languageEnglish
Pages (from-to)13218-13225
Number of pages8
JournalACS applied materials & interfaces
Volume10
Issue number15
DOIs
Publication statusPublished - 18 Apr 2018

Keywords

  • UT-Hybrid-D
  • Conductive AFM
  • Fermi-level pinning
  • Heterojunctions
  • MoWSe
  • Schottky barrier
  • Transition metal dichalcogenide alloys
  • 2D semiconductor

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