Tip-Mediated Bandgap Tuning for Monolayer Transition Metal Dichalcogenides

Meng Kai Lin, Guan Hao Chen, Ciao Lin Ho, Wei Chen Chueh, Joseph Andrew Hlevyack, Chia Nung Kuo, Tsu Yi Fu, Juhn Jong Lin, Chin Shan Lue, Wen Hao Chang, Noriaki Takagi, Ryuichi Arafune, Tai Chang Chiang, Chun Liang Lin

Research output: Contribution to journalArticlepeer-review

Abstract

Monolayer transition metal dichalcogenides offer an appropriate platform for developing advanced electronics beyond graphene. Similar to two-dimensional molecular frameworks, the electronic properties of such monolayers can be sensitive to perturbations from the surroundings; the implied tunability of electronic structure is of great interest. Using scanning tunneling microscopy/spectroscopy, we demonstrated a bandgap engineering technique in two monolayer materials, MoS2 and PtTe2, with the tunneling current as a control parameter. The bandgap of monolayer MoS2 decreases logarithmically by the increasing tunneling current, indicating an electric-field-induced gap renormalization effect. Monolayer PtTe2, by contrast, exhibits a much stronger gap reduction, and a reversible semiconductor-to-metal transition occurs at a moderate tunneling current. This unusual switching behavior of monolayer PtTe2, not seen in bulk semimetallic PtTe2, can be attributed to its surface electronic structure that can readily couple to the tunneling tip, as demonstrated by theoretical calculations.

Original languageEnglish
Pages (from-to)14918-14924
Number of pages7
JournalACS Nano
Volume16
Issue number9
DOIs
StatePublished - 27 Sep 2022

Keywords

  • bandgap engineering
  • monolayer
  • scanning tunneling microscopy
  • scanning tunneling spectroscopy
  • transition metal dichalcogenides

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