Widely used and most reliable growing technique for fabrication of large-scale graphene grains, a thermal decomposition on silicon carbide (SiC), significantly reduces the carrier mobility partially due to crystal imperfections and partially due to substrate phonons which collide with the charge carriers. Elimination of the substrate influence is therefore essential to keep the carrier mobility at a very high level. In our experiment, samples of multi-layer epitaxial graphene grown on SiC were exposed to intense 21.2-nm radiation provided by Ne-like Zn XUV laser driven by the Prague Asterix Laser System (PALS). A sub-nanosecond pulse of energetic (58.5 eV) photons is used to break relatively weak bonds between the SiC substrate and graphene while keeping the graphene layer almost unaffected. An irradiated area was inspected by micro-Raman spectroscopy, white-light interferometry (WLI), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Data show clear evidence of delamination of the multi-layer graphene which is elevated by 5 nm. Decrease of the mechanical strain and increase of number of defects in the irradiated area observed from Raman spectra is discussed.
|