Effect of the thin-film limit on the measurable optical properties of graphene.
The fundamental sheet conductance of graphene can be directly related to the product of its absorption coefficient, thickness and refractive index. The same can be done for graphene's fundamental opacity if the so-called thin-film limit is considered. Here, we test mathematically and experimentally the validity of this limit on graphene, as well as on thin metal and semiconductor layers. Notably, within this limit, all measurable properties depend only on the product of the absorption coefficient, thickness, and refractive index. As a direct consequence, the absorptance of graphene depends on the refractive indices of the surrounding media. This explains the difficulty in determining separately the optical constants of graphene and their widely varying values found in literature so far. Finally, our results allow an accurate estimation of the potential optical losses or gains when graphene is used for various optoelectronic applications.
Institute of Physics of the Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha, Czech Republic.|CTU in Prague, Faculty of Electrical Engineering, Technická 2, 166 27 Prague, Czech Republic.
Jakub
J
Holovský
École Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, Maladière 71, CH-2000 Neuchâtel, Switzerland.
Sylvain
S
Nicolay
École Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, Maladière 71, CH-2000 Neuchâtel, Switzerland.
Stefaan
S
De Wolf
École Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, Maladière 71, CH-2000 Neuchâtel, Switzerland.
Christophe
C
Ballif