Reversible hydrogenation and band gap opening of graphene and graphite surfaces probed by scanning tunneling spectroscopy

摘要

The effect of hydrogenation on the topography and the electronic propertiesof graphene and graphite surfaces are studied by scanning tunneling microscopyand spectroscopy. The surfaces are chemically modified using Ar/H2 plasma.Analyzing thousands of scanning tunneling spectroscopy measurements wedetermine that the hydrogen chemisorption on the surface of graphite/grapheneopens on average an energy band gap of 0.4 eV around the Fermi level. We findthat although the plasma treatment modifies the surface topography in anon-reversible way, the change in the electronic properties can be reversed bya moderate thermal annealing and the samples can be hydrogenated again yieldinga similar, but slightly reduced, semiconducting behavior after the secondhydrogenation.