Quasi-free-standing monolayer and bilayer graphene growth on homoepitaxial on-axis 4H-SiC(0 0 0 1) layers

Abstract

Quasi-free-standing monolayer and bilayer graphene growth on homoepitaxial on-axis 4H-SiC (0001) The doping of the SiC epilayers may be modified allowing for graphene to be grown on a conducing substrate. Graphene growth was performed via thermal decomposition of the surface of the SiC epilayers under Si background pressure in order to achieve control on thickness uniformity over large area. Monolayer and bilayer samples were prepared through the conversion of a carbon buffer layer and monolayer graphene respectively using hydrogen intercalation process. Micro-Raman and reflectance mappings confirmed predominantly quasi-free-standing monolayer and bilayer graphene on samples grown under optimized growth conditions.Measurements of the Hall properties of Van der Pauw structures fabricated on these layers show high charge carrier mobility (>2000 cm 2 /Vs) and low carrier density (<0.9x10 13 cm -2 ) in quasifree-standing bilayer samples relative to monolayer samples. Also, bilayers on homoepitaxial layers are found to be superior in quality compared to bilayers grown directly on SI substrates.

Eco‐friendly produced lightweight structural graphene/polyamide 12 nanocomposite: Mechanical performance and the controlling microstructural mechanisms

“…The significant down shift of the G and 2D bands to lower wavenumbers in the PNCs spectra, compared to their corresponding positions in the GL‐GNPs spectrum, is indicative of the good interactions between GL‐GNPs and PA12 chains. Furthermore, being the 2D band sharper in the PNCs spectra than in the GL‐GNPs spectrum, it can be speculated the extra‐exfoliation of the GL‐GNPs flakes within PNCs as a result of the applied ultrasonic power during the compounding process. The third new band observed at 2,235 cm −1 in PG0.5 and at 2,240 cm −1 in PG1 can be attributed to the nitrile CN and/or isocyanate NCO stretching vibration .…”

Quasi free-standing epitaxial graphene fabrication on 3C–SiC/Si(111)

“…So far the fabrication of free-standing graphene has been considered only on bulk SiC [30][31][32][33][37][38][39][40][41][42]; due to the technological importance of SiC/Si we explored the production of free-standing graphene by hydrogen intercalation on 3C-SiC thin films on Si(111). We combine, for the first time, synchrotron radiation near-edge X-ray absorption fine structure (NEXAFS) with core-level photoelectron spectroscopy (PES) and low energy electron diffraction (LEED), with the aim of obtaining a clear picture of the intercalation process on graphene grown on 3C-SiC/Si(111).…”

Bifunctional effects of the ordered Si atoms intercalated between quasi-free-standing epitaxial graphene and SiC(0001): graphene doping and substrate band bending

“…However, the ZL plays an important role in passivating the dangling bonds of the SiC(0001) substrate, so that the overlying graphene layer exhibits truly delocalized π orbitals. An elegant way to remove the undesirable influence of the ZL on the overlying graphene is to prepare so-called quasi-free-standing epitaxial graphene (EG) through decoupling the ZL from the substrate [2] by the intercalation of various elements such as H [5,[10][11][12][13][14][15][16][17], Li [18], Na [19], O [20][21][22], F [2,23], Au [9,24], Cu [25], Fe [26,27], Yb [28], Al [29], Pt [30], Ge [7,31,32] and Si [33][34][35]. Among them, semiconducting elements in group IV, like Si and Ge, turn out to be easily intercalated by deposition at room temperature (RT) and…”