Band-bending at the graphene-SiC interfaces: effect of the substrate

In-situ synchrotron-based photoemission spectroscopy, low-temperature scanning tunneling microscopy and Raman spectroscopy are used to investigate the interface properties of graphene on both the (0001) and (0001) 6H-SiC (Si- and C-terminated surfaces). We clearly observe the upward band-bending upon the formation of interfacial graphene, which depends on the surface polarity of the underlying SiC substrate, i.e., a weak upward band bending by 0.4 eV forms on the Si-terminated 6H-SiC(0001); while a much larger upward band bending by 1.3 eV appears on the C-terminated 6H-SiC(0001)