%0 Journal Article
%T Is the Registry Between Adjacent Graphene Layers Grown on C-Face SiC Different Compared to That on Si-Face SiC
%A Leif I. Johansson
%A Chao Xia
%A Jawad Ul Hassan
%A Tihomir Iakimov
%A Alexei A. Zakharov
%A Somsakul Watcharinyanon
%A Rositza Yakimova
%A Erik Janz¨¦n
%A Chariya Virojanadara
%J Crystals
%D 2013
%I MDPI AG
%R 10.3390/cryst3010001
%X Graphene grown on C-face SiC substrates using two procedures, high and low growth temperature and different ambients, was investigated using Low Energy Electron Microscopy (LEEM), X-ray Photo Electron Electron Microscopy (XPEEM), selected area Low Energy Electron Diffraction (¦Ì-LEED) and selected area Photo Electron Spectroscopy (¦Ì-PES). Both types of samples showed formation of ¦Ìm-sized grains of graphene. The sharp (1 ¡Á 1) ¦Ì-LEED pattern and six Dirac cones observed in constant energy photoelectron angular distribution patterns from a grain showed that adjacent layers are not rotated relative to each other, but that adjacent grains in general have different azimuthal orientations. Diffraction spots from the SiC substrate appeared in ¦Ì-LEED patterns collected at higher energies, showing that the rotation angle between graphene and SiC varied. C 1s spectra collected did not show any hint of a carbon interface layer. A hydrogen treatment applied was found to have a detrimental effect on the graphene quality for both types of samples, since the graphene domain/grain size was drastically reduced. From hydrogen treated samples, ¦Ì-LEED showed at first a clear (1 ¡Á 1) pattern, but within minutes, a pattern containing strong superstructure spots, indicating the presence of twisted graphene layers. The LEED electron beam was found to induce local desorption of hydrogen. Heating a hydrogenated C-face graphene sample did not restore the quality of the original as-grown sample.
%K C-face graphene
%K layer registry
%K large grain sizes
%K sublimation growth
%K hydrogen treatment
%U http://www.mdpi.com/2073-4352/3/1/1