Quantum oscillations and quantum Hall effect in epitaxial graphene

Abstract

We investigate the transport properties of high-quality single-layer graphene, epitaxially grown on a 6H-SiC͑0001͒ substrate. We have measured transport properties, in particular charge-carrier density, mobility, conductivity, and magnetoconductance of large samples as well as submicrometer-sized Hall bars which are entirely lying on atomically flat substrate terraces. The results display high mobilities, independent of sample size. The temperature dependence of the conductance indicates a rather strong coupling to the SiC substrate. An analysis of the Shubnikov-de Haas effect yields the Landau-level spectrum of single-layer graphene. When gated close to the Dirac point, the mobility increases substantially and the graphenelike quantum Hall effect occurs.

Tuning the charge carriers in epitaxial graphene on SiC(0001) from electron to hole via molecular doping with C60F48

“…This has been independently shown in studies employing angleresolved photoelectron spectroscopy (ARPES), 10,11 as well as room temperature transport measurements. 12 Therefore, no true p-type doping of graphene grown on SiC using organic molecules has been achieved as yet. Here, we show that an increasing coverage of the high electron affinity molecule C 60 F 48 on graphene is able to control the carrier concentration and change the sign of the carriers from n-type to p-type.…”

Observation of quantum-Hall effect in gated epitaxial graphene grown on SiC (0001)

“…During the preparation and revision of this manuscript, we became aware of similar observations of the graphene-like QHE on both Si-face and C-face of SiC substrates. [20][21][22] The authors would like to thank J.A. Cooper Jr., L.P. Rokhinson and A.T. Neal for valuable discussions, and G. Jones, T. Murphy and E. Palm at National High Magnetic Field Laboratory (NHMFL) for experimental assistance.…”

Graphene synthesis: a Review

“…On the other hand, similar to graphene obtained by drawing or peel off method, SiC-epitaxial graphene displays extremely large, temperature independent mobility but not as high as exfoliated graphene [96]. Even without transfer, graphene obtained through this method displays massless Dirac fermions [85,[96][97][98][99][100][101]. In multi-layered epitaxial graphene, weak van der Waals forces responsible for multilayer cohesion do not necessarily impact electronic properties of individual sheets within a stack.…”

“…Graphene obtained from this procedure tends to have weak anti-localization, unlike exfoliated graphene [95]. On the other hand, similar to graphene obtained by drawing or peel off method, SiC-epitaxial graphene displays extremely large, temperature independent mobility but not as high as exfoliated graphene [96]. Even without transfer, graphene obtained through this method displays massless Dirac fermions [85,[96][97][98][99][100][101].…”