Direct observation of trapped charges at ReSe2 and graphene heterojunctions

Trinh Thi Ly, Yun Jae Lee, Byoung Ki Choi, Hojun Lee, Hyuk Jin Kim, Ganbat Duvjir, Nguyen Huu Lam, Kyuha Jang, Krisztián Palotás, Young Jun Chang, Aloysius Soon, Jungdae Kim

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The van der Waals (vdW) heterojunction often reveals unexpected characteristics distinct from conventional junctions. We investigate an emergent interface phenomenon between monolayer ReSe2 and graphene via combined studies of scanning tunneling microscopy (STM) and density functional theory (DFT). When probing monolayer ReSe2 on graphene at bias voltages within the ReSe2 band gap (in-gap bias; −1.2 V to 0.5 V), strikingly, observed topograph appears just like ReSe2 as it shows precisely the same hexagonal periodicity of ReSe2 lattice instead of the underlying graphene lattice. To answer this puzzle, we examine the nature of charge redistribution at the confined vdW gap between ReSe2 and graphene. DFT calculations indicate that the electron accumulation arises right below the ReSe2 layer, while the electron depletion occurs from the graphene layer. This leads to an asymmetrically polarized two-dimensional layer of confined electron density (termed as trapped charges) in the vdW gap, which agrees well with the in-gap STM topograph. We also find that the accumulation of the trapped charge is enhanced strongly at the edge of ReSe2.

Original languageEnglish
Article number152187
JournalApplied Surface Science
StatePublished - 30 Mar 2022


  • Charge redistribution
  • Density functional theory
  • ReSe
  • Scanning tunneling microscopy
  • Trapped charge
  • van der Waals heterojunction


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