AVS 58th Annual International Symposium and Exhibition
    Graphene and Related Materials Focus Topic Wednesday Sessions
       Session GR-WeA

Paper GR-WeA10
Imaging Epitaxial Graphene on SiC(0001) using STM with Functionalized W Tips

Wednesday, November 2, 2011, 5:00 pm, Room 208

Session: Graphene Characterization including Microscopy and Spectroscopy
Presenter: Sonny Rhim, University of Wisconsin-Milwaukee
Authors: S.H. Rhim, University of Wisconsin-Milwaukee
Y. Qi, University of Wisconsin-Milwaukee
G.F. Sun, University of Wisconsin-Milwaukee
Y. Liu, University of Wisconsin-Milwaukee
M. Weinert, University of Wisconsin-Milwaukee
L. Li, University of Wisconsin-Milwaukee
Correspondent: Click to Email
Epitaxial graphene on SiC(0001) is studied using scanning tunneling microscopy with W tips functionalized by transition metal (Cr, Fe) coating, which enables the imaging of states within a few meV of the Fermi level that are not accessible with conventional W tips. Modeling of these tips using X/W(110) (X=Cr, Fe, W) by first-principles calculations indicates that states responsible for enhanced tunneling are located 0.4~0.6 eV above and below EF for Fe/W tips, and 0.3 eV above EF for Cr/W tips. Further calculations show that the formation of an apex atom is not stable for W/W(110) or Fe/W(110) tips, but is stable for Cr/W(110) tips, resulting in point-like iso-density of states contours that are ideal for the selective imaging of the complex electronic properties of the epitaxial graphene on SiC(0001).