Band Alignment at Au/MoS2 Contacts: Thickness Dependence of Exfoliated Flakes

Ahrum Sohn, Hankyoul Moon, Jayeong Kim, Miri Seo, Kyung Ah Min, Sang Wook Lee, Seokhyun Yoon, Suklyun Hong, Dong Wook Kim

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We investigated the surface potential (Vsurf) of exfoliated MoS2 flakes on bare and Au-coated SiO2/Si substrates using Kelvin probe force microscopy. The Vsurf of MoS2 single layers was larger on the Au-coated substrates than on the bare substrates; our theoretical calculations indicate that this may be caused by the formation of a larger electric dipole at the MoS2/Au interface leading to a modified band alignment. Vsurf decreased as the thickness of the flakes increased until reaching the bulk value at a thickness of a20 nm (a30 layers) on the bare and a80 nm (a120 layers) on the Au-coated substrates, respectively. This thickness dependence of Vsurf was attributed to electrostatic screening in the MoS2 layers. Thus, a difference in the thickness at which the bulk Vsurf appeared suggests that the underlying substrate has an effect on the electric-field screening length of the MoS2 flakes. This work provides important insights to help understand and control the electrical properties of metal/MoS2 contacts.

Original languageEnglish
Pages (from-to)22517-22522
Number of pages6
JournalJournal of Physical Chemistry C
Volume121
Issue number40
DOIs
StatePublished - 12 Oct 2017

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