Orientation-dependent work function of graphene on Pd(111)

Abstract

Selected-area diffraction establishes that at least six different in-plane orientations of monolayer graphene on Pd(111) can form during graphene growth. From the intensities of low-energy electron microscopy images as a function of incident electron energy, we find that the work functions of the different rotational domains vary by up to 0.15 eV. Density functional theory calculations show that these significant variations result from orientation-dependent charge transfer from Pd to graphene. These findings suggest that graphene electronics will require precise control over the relative orientation of the graphene and metal contacts.