Epitaxial graphene on6H-SiCand Li intercalation

Authors:
  • CVC. Virojanadara
    C. Virojanadara
  • SWS. Watcharinyanon
    S. Watcharinyanon
  • AZA. A. Zakharov
    A. A. Zakharov
  • LJL. I. Johansson
    L. I. Johansson
Publisher website
Google Scholar
Abstract
The influence of lithium (Li) exposures on monolayer graphene grown on the silicon-terminated SiC(0001) surface is investigated using low-energy electron microscopy, photoelectron spectroscopy, and micro-low-energy electron diffraction. After Li deposition, islands or Li droplets are observed on the surface, and are found to coalesce together with time. Formation of a dipole layer at the interface, interpreted to originate from Li-Si bonding, is observed directly after Li deposition, and manifested by a 2 eV shift of the C\,1s and Si\,2p bulk SiC peaks. This indicates that Li atoms penetrate through the graphene and carbon buffer layer directly after deposition at room temperature since three $\pi${} bands are then moreover observed at the K point, instead of the single $\pi${} band for monolayer graphene. The existence of three $\pi${} bands is interpreted as a mixture of bilayer and monolayer graphene plus a difference in doping levels due to an uneven distribution of Li atoms. Li gives rise to electron doping of the graphene and results in a lowering of the Dirac point. After annealing to a few hundred degrees Celsius, a more even Li distribution and intercalation is obtained since then two distinct $\pi${} bands appear at the K point.

This publication has 14 references indexed in Scilit: