Band structure engineering of epitaxial graphene on SiC by molecular doping

摘要: Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland(Dated: March 16, 2010)Epitaxial graphene on SiC(0001) suffers from strong intrinsic n-type doping. We demonstrate thatthe excess negative charge can be fully compensated by non-covalently functionalizing withthe electron acceptor tetrafluorotetracyanoquinodimethane (F4-TCNQ). Charge neutralitycan reached in monolayer as shown dispersion spectra angular re-solved photoemission spectroscopy (ARPES). In bilayer the band gap that originates fromthe SiC/graphene interface dipole increases with increasing F4-TCNQ deposition and, a con-sequence of molecular doping, Fermi level is shifted into gap. The reduction ofthe carrier density upon quantified using electronic surfacesand Raman spectroscopy. structural and characteristics graphene/F4-TCNQcharge transfer complex are investigated X-ray photoelectron (XPS) ultravioletphotoelectron (UPS). doping effect preserved air temper-ature resistant up to 200