Growth kinetics of epitaxial graphene on SiC substrates

Optical absorption and Raman scattering studies of epitaxial graphene structures obtained by annealing of carbon terminated face of $4H\text{-SiC}\left(000\text{−}1\right)$ on-axis substrates using standard chemical-vapor deposition reactor are presented. Two series of samples grown at different argon pressures in the reactor and different annealing times were studied. Optical absorption and Raman scattering were used to determine the number of graphene layers formed on the substrate surface. The observed dependence of the number of graphene layers formed on annealing time and argon pressure strongly indicates that the growth kinetics of graphene is limited by Si evaporation and two-dimensional Si diffusion.

Figure 1

(Color online) Circles: the optical absorption dependence on argon pressure during growth process at temperature $T=1600°\text{C}$ and annealing time $t=10\text{min}$. Right axis corresponds to the number of graphene layers, calculated according to Eq. (2). Triangles: integrated intensity (in arbitrary units) of 2D band Raman signal.

Figure 2

(Color online) Representative normalized Raman spectra obtained for samples fabricated at different argon pressure in the CVD reactor and the same annealing time of 10 min at $1600°\text{C}$.

Figure 3

(Color online) The optical absorption dependence on annealing time in growth process at temperature $T=1600°\text{C}$ and argon pressure $p=100\text{mbar}$ in the log-log scale. Right axis corresponds to the number of graphene layers, calculated according to Eq. (2). Dashed line and solid line: power-law dependence with the exponents 0.5 and 0.35, respectively.