AVS 64th International Symposium & Exhibition
    2D Materials Focus Topic Wednesday Sessions
       Session 2D-WeA

Paper 2D-WeA9
Spatially Resolved Modification of Graphene's Band Structure by Surface Oxygen Atoms

Wednesday, November 1, 2017, 5:00 pm, Room 15

Session: Properties and Characterization of 2D Materials
Presenter: David Y. Lee, Washington State University
Authors: C. Harthcock, Washington State University
A. Jahanbekam, Washington State University
Y. Zhang, Washington State University
D.Y. Lee, Washington State University
Correspondent: Click to Email
We report the spatially resolved modification of the topography and electronic properties of monolayer graphene by low dosage of atomic oxygen in the nm-scale. Using an ultra-high vacuum scanning tunneling microscope, we show that surface O-atoms, even at a low coverage of O/C = ~1/150, form random surface distributions and clusters of various sizes. Using scanning tunneling spectroscopy, oxygen adsorbates are observed to be p-type dopants, which leads to site-dependent partial and full band modifications up to a gap of few hundred meV. The degree of band gap opening and the number of O-atom induced charge-holes per area are inversely proportional to the distance between the position at which each STS spectrum is collected and the location of the nearest adsorbate. However, the number of holes contributed per oxygen atom was found to be a site-independent constant of 0.15±0.05. For a small population of adsorbates taller than 4Å, the graphene energy bands are no longer resolved; instead STS measurements show very spatially localized but high density of states over a wide energy range, which indicates sole tunneling contribution from the cluster of electron-rich O-atoms and a complete decoupling from the graphene bands