▎ 摘　　要

We show that for metal/graphene/dielectric sandwich structures, charge doping in graphene depends on both the work functions of the metal and the dielectric. Using C-1s core level photoemission spectroscopy we determine the charge doping in graphene for one-sided metal contacts as well as for sandwich structures that are commonly used in graphene devices. The measured Fermi-level shifts are in good agreement with a model that predicts that the difference in charge doping for graphene on a metal compared to graphene sandwiched between a metal and dielectric is given by Delta E-F approximate to 0.44 x root(Phi(metal) - Phi(dielectric)). (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.