The adsorption structure and the electronic property of azidotrimethyltin (ATMT) on monolayer graphene were investigated using scanning tunneling microscopy and core-level photoemission spectroscopy. We also confirmed the n-type doping effect by scanning tunneling spectroscopy and work function measurements. We will systematically demonstrate the variation of characteristic of graphene induced by the chemical functionalized molecule as we confirmed the results using scanning tunneling microscopy in conjunction with core- level photoemission spectroscopy. (C) 2011 Elsevier B.V. All rights reserved.