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

Abstract

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
Volume579
DOIs
Publication statusPublished - 2022 Mar 30

Bibliographical note

Funding Information:
This work was supported by National Research Foundation (NRF) grants funded by the Korean government (nos. NRF-2018R1D1A1B07050144, NRF-2019R1A6A1A11053838, NRF-2021R1A6A3A14040322, NRF-2020R1A2C200373211) and by the Technology Innovation Programme (20012430) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea). Computational resources have been kindly provided by the KISTI Super-computing Center (KSC-2021-CRE-0044) and the Australian National Computational Infrastructure (NCI). K. P. acknowledges support of the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences, and the National Research Development and Innovation Office of Hungary under grant no. FK124100.

Funding Information:
This work was supported by National Research Foundation (NRF) grants funded by the Korean government (nos. NRF-2018R1D1A1B07050144 , NRF-2019R1A6A1A11053838 , NRF-2021R1A6A3A14040322 , NRF-2020R1A2C200373211 ) and by the Technology Innovation Programme ( 20012430 ) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) . Computational resources have been kindly provided by the KISTI Super-computing Center ( KSC-2021-CRE-0044 ) and the Australian National Computational Infrastructure (NCI) . K. P. acknowledges support of the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences, and the National Research Development and Innovation Office of Hungary under grant no. FK124100.

Publisher Copyright:
© 2021 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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