Doping characteristics of iodine on as-grown chemical vapor deposited graphene on Pt

Using laboratory X-ray photoelectron emission microscopy (XPEEM), we investigated the doping efficiency and thermal stability of iodine on as-grown graphene on Pt. After iodine adsorption of graphene in saturated vapor of I-2, monolayer and bilayer graphene exhibited work function of 4.93 eV and 4.87 eV, respectively. Annealing of the doped monolayer graphene at 100 degrees C led to desorption of hydrocarbons, which increased the work function of monolayer graphene by similar to 0.2 eV. The composition of the polyiodide complexes evolved upon a step-by-step annealing at temperatures from 100 degrees C to 300 degrees C while the work-function non-monotonically changed with decreasing iodine content. The iodine dopant was stable at relatively high temperature as a significant amount of iodine remained up to the annealing temperature of 350 degrees C. (C) 2015 Elsevier B.V. All rights reserved.