Observation of Quantum Hall Effect and weak localization in p-type bilayer epitaxial graphene on SiC(0001)

• We studied magnetotransport properties of a bilayer graphene grown on SiC(0001).
• Integer quantum Hall effect and weak localization effect were observed.
• No weak antilocalization was observed in sample due to strong intervally scattering.
• Strong intervally scattering is caused by large amount of atomically sharp defects.
• Direct Coulomb interaction also exists in inelastic-scattering.

We investigated the magnetotransport properties of a bilayer graphene Hall bar sample epitaxially grown on Si-terminated silicon carbide. Integer quantum Hall effect and weak localization effect were observed. From the weak localization effect, the carrier scattering and phase coherence were extracted. The extracted phase coherence length is 0.5 μm at 2 K, which is comparable with that of the exfoliated graphene. The temperature dependence of the phase coherence rate shows that electron–electron interaction is the main inelastic-scattering factor and direct Coulomb interaction also exists. Compared with exfoliated bilayer graphene, no sign of weak antilocalization was observed at such high carrier concentration of 1013 cm−2 due to the strong intervally scattering. Both the strong intervally scattering and Coulomb interaction of phase coherence are due to the large amount of atomically sharp defects in epitaxial graphene on Si-terminated SiC.