Department of Physics and Astronomy, Aarhus University
Functionalization of graphene on Ir(111)
with hydrogen represents a possible route towards a band gap opening in the
otherwise semimetallic material. XPS data on hydrogenated graphene on
Ir(111) have shown that hydrogen binds to the carbon atoms of graphene with
different energies depending on the carbon position in the Moiré
superstructure. Here we present a combined Scanning Tunnelling Microscopy
(STM) and angle resolved photoemission spectroscopy (ARPES) study of hydrogen
structures and the corresponding band gaps obtained following exposure of a hot
graphene coated Ir(111) surface to atomic hydrogen. The hot surface favours the
binding of hydrogen only in the most stable positions yielding a well organized
hexagonal pattern of hydrogen clusters. Images suggest that the clusters are
confined to the FCC sites of the Moiré pattern contrary to room temperature
deposition where extended clusters are observed1. ARPES measurements reveal a
highly tunable band gap depending on the sample temperature during
hydrogenation with values ranging from 450 meV at room temperature, 281 meV at
645K to 148 meV at 675K. We are thus able to tune the gap merely by adjusting
the sample temperature.
1. Balog, R., et al., Nature Materials,
2010. 9(4): p. 315-319.
2. Balog, R., et al., Acs Nano, 2013. 7(5):
3. N'Diaye, A.T., et al., New Journal of
Physics, 2008. 10: p. 16.
Jakob Jørgensen is
currently a PhD student in Nanoscience at the Interdisciplinary Nanoscience
Center at Aarhus University. He is
primarily interested in the electronic properties of graphene. He received his
B.S. degree in Nanoscience (2012) and a MSc in Nanoscience (2012) from Aarhus
University where he studied functionalization of graphene.