Uniform coverage of quasi-free standing monolayer graphene on SiC by hydrogen intercalation

Buffer layer (BL) was grown on the Si-face of semi-insulating SiC substrates by thermal decomposition. The Raman spectra were correlated with the surface potential obtained by Kelvin probe force microscopy to assuredly confirm the complete coverage of the BL on SiC substrates. Subsequently, quasi-free standing monolayer graphene (QFSMG) was achieved by hydrogen intercalation. And moreover, different hydrogen annealing temperature was chosen in order to study the process of hydrogen intercalation. Raman and X-ray photoelectron spectroscopy measurements distinctly revealed the changes of QFSMG with varied hydrogen annealing temperature. In particular, a large number of Raman data were collected to indicate the differences of uniformity. Additionally, the peak of Si–H bonding vibration mode was observed by surface enhanced Raman scattering, which was the direct evidence to show the success of hydrogen intercalation. All results indicated that the optimized annealing temperature was about 900 °C for obtaining uniform coverage of high-quality QFSMG with low density of defects.