Toward barrier free contact to molybdenum disulfide using graphene electrodes

Nano Lett. 2015 May 13;15(5):3030-4. doi: 10.1021/nl504957p. Epub 2015 Apr 22.

Abstract

Two-dimensional layered semiconductors such as molybdenum disulfide (MoS2) have attracted tremendous interest as a new class of electronic materials. However, there are considerable challenges in making reliable contacts to these atomically thin materials. Here we present a new strategy by using graphene as the back electrodes to achieve ohmic contact to MoS2. With a finite density of states, the Fermi level of graphene can be readily tuned by a gate potential to enable a nearly perfect band alignment with MoS2. We demonstrate for the first time a transparent contact to MoS2 with zero contact barrier and linear output behavior at cryogenic temperatures (down to 1.9 K) for both monolayer and multilayer MoS2. Benefiting from the barrier-free transparent contacts, we show that a metal-insulator transition can be observed in a two-terminal MoS2 device, a phenomenon that could be easily masked by Schottky barriers found in conventional metal-contacted MoS2 devices. With further passivation by boron nitride (BN) encapsulation, we demonstrate a record-high extrinsic (two-terminal) field effect mobility up to 1300 cm(2)/(V s) in MoS2 at low temperature.

Keywords: MoS2; barrier free; graphene contact; high mobility; layered materials; ohmic contact.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Boron Compounds / chemistry*
  • Disulfides / chemistry*
  • Electrodes
  • Graphite / chemistry
  • Molybdenum / chemistry*
  • Nanostructures
  • Nanotechnology*
  • Semiconductors*

Substances

  • Boron Compounds
  • Disulfides
  • boron nitride
  • Graphite
  • Molybdenum
  • molybdenum disulfide