Fermi Level Depinning in Two-Dimensional Materials Using a Fluorinated Bilayer Graphene Barrier

Cunzhi Sun, Cheng Xiang, Rongdun Hong, Feng Zhang, Timothy J. Booth, Peter Bøggild*, Manh Ha Doan

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Strong Fermi level pinning (FLP), often attributed to metal-induced gap states at the interfacial contacts, severely reduces the tunability of the Schottky barrier height of the junction and limits applications of two-dimensional (2D) materials in electronics and optoelectronics. Here, we show that fluorinated bilayer graphene (FBLG) can be used as a barrier to effectively prevent FLP at metal/2D material interfaces. FLBG can be produced via short exposure (1-3 min) to SF6 plasma that fluorinates only the top layer of a bilayer graphene with covalent C-F bonding, while the bottom layer remains intrinsic, resulting in a band gap opening of about 75 meV. Inserting FBLG between the metallic contacts and a layer of MoS2 reduces the Schottky barrier height dramatically for the low-work function metals (313 and 260 meV for Ti and Cr, respectively) while it increases for the high-work function one (160 meV for Pd), corresponding to an improved pinning factor. Our results provide a straightforward method to generate atomically thin dielectrics with applications not only for depinning the Fermi level at metal/transition metal dichalcogenide interfaces but also for solving many other problems in electronics and optoelectronics.

Original languageEnglish
JournalACS Applied Electronic Materials
Issue number8
Pages (from-to)3955-3961
Publication statusPublished - 2022


  • 2D materials
  • Band gap opening
  • Bilayer graphene
  • Fermi level pinning
  • Schottky barrier


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