Liv Hornekær Discusses Hydrogen Functionalization of Graphene

New Hot Paper Commentary, July 2011

Liv Hornekær

Article: Bandgap opening in graphene induced by patterned hydrogen adsorption


Authors: Balog, R;Jorgensen, B;Nilsson, L;Andersen, M;Rienks, E;Bianchi, M;Fanetti, M;Laegsgaard, E;Baraldi, A;Lizzit, S;Sljivancanin, Z;Besenbacher, F;Hammer, B;Pedersen, TG;Hofmann, P;Hornekaer, L
Journal: NAT MATER
Volume: 9, Issue: 4, Page: 315-319, Year: APR 2010
* Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark.
* Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark.
(Addresses have been truncated)

Liv Hornekær talks with ScienceWatch.com and answers a few questions about this month's New Hot Paper in the field of Materials Science.


SW: Why do you think your paper is highly cited?

Opening a band gap in graphene of sufficient size for real applications is one of the holy grails in graphene research. Our results show that this is indeed possible using patterned chemical functionalization and hence opens up new possibilities in this very dynamic research field.

At the same time the demonstrated method also gives rise to a wide range of questions—what aspects of the method are crucial for the band gap opening? How can the method be generalized to produce graphene with a band gap on insulating substrates? What happens with the mobility of the charge carriers in the patterned graphene structure? Hence the paper both opens up new possibilities and poses new questions in graphene research.

SW: Does it describe a new discovery, methodology, or synthesis of knowledge?

Fig 1: a) and b) Scanning Tunneling Microscopy images of clean and hydrogenated graphene. c) and d) Ultraviolet Photoemission Spectroscopy measurements of the corresponding band structure.
Figure description: a) and b) Scanning Tunneling Microscopy images of clean and hydrogenated graphene. c) and d) Ultraviolet Photoemission Spectroscopy measurements of the corresponding band structure.

It describes the first experimental demonstration of a method to open up a band gap in wide area graphene of sufficient size to be useful for real applications.

SW: Would you summarize the significance of your paper in layman's terms?

Graphene, a single layer of graphite, has unique physical properties which make it interesting both as a playground for studying new fundamental physics and as a possible future material for electronic circuit fabrication. Most notably the charge carriers in graphene have very high mobility, exhibit ballistic transport properties and behave like mass-less relativistic Dirac fermions. These characteristics potentially make graphene an ideal material for electronic device fabrication.

However, graphene lacks a band gap around the Fermi level, which is the defining concept for semiconductor materials and essential for controlling the conductivity by electronic means. Several approaches to engineer a band gap opening in graphene have been suggested, but until recently experimental realizations have been limited to gap openings too small for room-temperature operation. By hydrogen functionalization of graphene we have demonstrated the opening of a band gap of ~1.0 eV, sufficiently large for real applications.

SW: How did you become involved in this research, and how would you describe the particular challenges, setbacks, and successes that you've encountered along the way?

Our specific approach to band gap engineering in graphene—namely by hydrogen functionalization—was inspired by many years of research in the interaction of atomic hydrogen with graphite and polycyclic aromatic hydrocarbons (partly under ERC StG HPAH)—mainly in connection with laboratory simulations of interstellar surface chemistry.

SW: Where do you see your research leading in the future?

Our present aim is to investigate to what extent this method can be generalized to other substrates and to answer some of the questions which the results raise—what characteristics of the chemical functionalization structures are crucial for the band gap opening? How can the method be generalized to produce graphene with a band gap on insulating substrates? What happens with the mobility of the charge carriers in the patterned graphene structure?End

Liv Hornekær, Associate professor
Department of Physics and Astronomy
and
Interdisciplinary Nanoscience Center (iNANO)
Aarhus University
Aarhus, Denmark

KEYWORDS: GRAPHENE, BANDGAP OPENING, PATTERNED HYDROGEN ADSORPTION, EPITAXIAL GRAPHENE, ATOMIC HYDROGEN.

 
 

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