• 文献标题:   Microscopic correlation between chemical and electronic states in epitaxial graphene on SiC(000(1)over-bar)
  • 文献类型:   Article
  • 作  者:   MATHIEU C, BARRETT N, RAULT J, MI YY, ZHANG B, DE HEER WA, BERGER C, CONRAD EH, RENAULT O
  • 作者关键词:  
  • 出版物名称:   PHYSICAL REVIEW B
  • ISSN:   2469-9950 EI 2469-9969
  • 通讯作者地址:   IRAMIS SPCSI LENSIS
  • 被引频次:   53
  • DOI:   10.1103/PhysRevB.83.235436
  • 出版年:   2011

▎ 摘  要

We present energy filtered electron emission spectromicroscopy with spatial and wave-vector resolution on few-layer epitaxial graphene on SiC(000 (1) over bar) grown by furnace annealing. Low-energy electron microscopy shows that more than 80% of the sample is covered by 2-3 graphene layers. C1s spectromicroscopy provides an independent measurement of the graphene thickness distribution map. The work function, measured by photoelectron emission microscopy (PEEM), varies across the surface from 4.34 to 4.50 eV according to both the graphene thickness and the graphene-SiC interface chemical state. At least two SiC surface chemical states (i.e., two different SiC surface structures) are present at the graphene/SiC interface. Charge transfer occurs at each graphene/SiC interface. k-space PEEM gives 3D maps of the |(k) over bar (parallel to)| pi-pi* band dispersion in micron-scale regions showing that the Dirac point shifts as a function of graphene thickness. Bragg diffraction of the Dirac cones via the superlattice formed by the commensurately rotated graphene sheets is observed. The experiments underline the importance of lateral and spectroscopic resolution on the scale of future electronic devices in order to precisely characterize the transport properties and band alignments.