Hidden surface channel in two-dimensional multilayers

Youkyung Seo, Soo Yeon Kim, Yeeun Kim, Chulmin Kim, Byung Chul Lee, Yoon Hee Park, Minji Chae, Youjin Hong, Min Kyung Seong, Changhyun Ko, Alessandro Cresti, Christoforos Theodorou, Gyu Tae Kim, Min Kyu Joo

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Numerous carrier scatterers, such as atomic defects, fixed oxide charges, impurities, chemical residues, and undesired surface adsorbates, including oxygen and water molecules, strongly degrade the carrier mobility of atomically thin two-dimensional (2D) materials. However, the effect of surface adsorbates and surface oxidation on the carrier density profile along the thickness of 2D multilayers is not well known, particularly for a substantial interruption in the formation of the top-surface channel. Here, we uncover a hidden surface channel in p-type black phosphorus and n-type rhenium disulfide multilayers originating from undesired ambient adsorbates and surface oxides that not only populate hole density (or reduce electron density) but also suppress carrier mobility. The absence of a second peak in the transconductance curve under ambient conditions indicates the disappearance of the top-surface channel inside the 2D multilayers, which is a possible indicator for the cleanliness of the top surface and can be used in gas sensor applications. Moreover, the negligible variation in the drain bias polarity-dependent turn-on voltage for the bottom channel under ambient conditions validates the exclusive contribution of surface adsorbates to the formation of the top channel in 2D multilayers. Our results provide a novel insight into the distinct carrier transport in 2D optoelectronic devices and diverse sensors.

Original languageEnglish
Article number035004
Journal2D Materials
Issue number3
Publication statusPublished - 2022 Jul

Bibliographical note

Funding Information:
This study was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (NRF-2019R1C1C1003467 & NRF-2022R1A2C4001245) and by Sookmyung Women’s University Research Grants (1-2203-2001).

Publisher Copyright:
© 2022 IOP Publishing Ltd.


  • carrier transport
  • interlayer resistance
  • multilayers
  • surface doping
  • two-dimensional materials

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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