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Jakob Jørgensen: Tunable band gap opening in graphene by high-temperature hydrogenation

posted 17 Jun 2015, 06:23 by info admin

iNANO and 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.[1] 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[2]. 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[3] 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): p. 3823-3832.

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.
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