Charge transfer and trapping as origin of a double dip in the transfer   characteristics of graphene based field-effect transistors
  We discuss the origin of an additional dip other than the charge neutrality point observed in transfer characteristics of graphene-based field-effect transistors. The double-dip is proved to arise from charge transfer between graphene and metal electrodes, while charge storage at the graphene/SiO2 interface enhances it. Considering different Fermi energy from the neutrality point along the channel and partial charge pinning at the contacts, we propose a model which explains all features in gate voltage loops. 
Antonio Di Bartolomeo, Filippo Giubileo, Salvatore Santandrea,   Francesco Romeo, Roberta Citro, Thomas Schroeder, And Grzeg...
cond-mat.mes-hall cond-mat.mtrl-sci