X‐Ray Spectroscopic Investigation of Chlorinated Graphene: Surface Structure and Electronic Effects |
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| Authors: | Xu Zhang Theanne Schiros Dennis Nordlund Yong Cheol Shin Jing Kong Mildred Dresselhaus Tomás Palacios |
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| Affiliation: | 1. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA;2. Energy Frontier Research Center (EFRC), Columbia University, New York, NY, USA;3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA;4. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA |
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| Abstract: | Chemical doping of graphene represents a powerful means of tailoring its electronic properties. Synchrotron‐based X‐ray spectroscopy offers an effective route to investigate the surface electronic and chemical states of functionalizing dopants. In this work, a suite of X‐ray techniques is used, including near edge X‐ray absorption fine structure spectroscopy, X‐ray photoemission spectroscopy, and photoemission threshold measurements, to systematically study plasma‐based chlorinated graphene on different substrates, with special focus on its dopant concentration, surface binding energy, bonding configuration, and work function shift. Detailed spectroscopic evidence of C–Cl bond formation at the surface of single layer graphene and correlation of the magnitude of p‐type doping with the surface coverage of adsorbed chlorine is demonstrated for the first time. It is shown that the chlorination process is a highly nonintrusive doping technology, which can effectively produce strongly p‐doped graphene with the 2D nature and long‐range periodicity of the electronic structure of graphene intact. The measurements also reveal that the interaction between graphene and chlorine atoms shows strong substrate effects in terms of both surface coverage and work function shift. |
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| Keywords: | chlorination graphene nonintrusive surface functionalization surface electronic state synchrotron‐based X‐ray spectroscopy |
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